Normalization of Deviance

Many divers, probably most divers, accept that diving can be truly dangerous. Of course, from time-to-time you’ll probably bump into someone who tells you and, most importantly, themselves that the risks associated with diving apply only to other people and not to them, but the majority of us are supremely aware that the Rottweilers can hit the fan on any dive, at any time, and for any number of different reasons. So it seems odd that there is so little mention in diving books and student manuals of the one “behavioral fault” common to the majority of dive fatalities.

Every year, the Diver’s Alert Network releases its report on diving incidents, injuries and fatalities. This is, in my opinion, the most valuable piece of data collection and analysis done by any organization within the dive community. It makes for compelling, but somewhat depressing reading. For example, in its 2010 report, it shares with us that there were 144 scuba-related deaths reported world-wide.

If we were to summarize the factors that contribute to dive fatalities, at least those in DAN’s report, we’d find four categories.

  1. Poor health (divers being really out of shape, on meds, ignoring common sense and diving with existing ailments or injuries).
  2. Procedural errors (things like not analyzing breathing gas, diving a rebreather with dodgy oxygen cells, running out of gas, etc.).
  3. Issues with the environment (getting into trouble because of changing conditions, like currents, visibility and the like).
  4. Problems with equipment (particularly serious in the world of rebreathers, but also including situations where a piece of kit goes pear-shaped and the diver freaks out and panics).

However, it seems to me that there is a fifth to add to that list, and its influence seeps into and significantly colors each of the other four. The Normalization of Deviance describes a dangerous facet of human nature. It goes something like this: We do something that does not follow the accepted (and acceptable) rules or guidelines – for example, we skip certain steps in a “standard” procedure because it saves time. The trouble stems from the unfortunate fact that we get away with taking the shortcut. Then, believing it’s safe to make the same safety shortcut next time around, we do the same thing… we ignore safe practice, established safe practice. In the absence of things going totally pear-shaped, our deviation from normal practice and safe procedure becomes a new acceptable norm.

The term Normalization of Deviance is from Diane Vaughan’s book on the Space Shuttle disaster, In that book, The Challenger Launch Decision, Vaughan, a professor in Columbia University’s Department of Sociology, points out that the component failure that contributed to the loss of the Space Shuttle, and the deaths of seven crew members on January 28, 1986, was predicted before the launch. The risks were known and documented!

She explains that normalization of deviance within NASA and Morton-Thiokol (the company that manufactured the solid rocket boosters (SRBs) used to propel the shuttle into space), allowed a recognized design flaw to be ignored. She writes: “As [NASA and Morton-Thiokol] recurrently observed the problem with no consequence they got to the point that flying with the flaw was normal and acceptable” In essence, flight plans made no allowances for a known issue with the SRBs.

This deviation from best practice resulted in what Vaughan termed a: Predictable Surprise. Eventually, luck ran out, the component failed and the shuttle disintegrated 73 seconds after launch killing five astronauts, two payload specialists, and grounding NASA’s shuttle program for almost three years.

Normalization of deviance – and the predictable surprises that follow – are part of that catch-all phenomenon too often observed during the accident analysis that follows failure of any high-stakes, high-risk endeavor. We call that phenomenon: Human Error.

Certainly normalization of deviance shows its ugly face in diving. Often. A classic example is the double deaths of Darrin Spivey, 35, and Dillon Sanchez, 15 on Christmas Day 2013. Spivey, certified only as an open-water diver, took Sanchez, his son, who held no recognized dive training or certification at any level, to try out new equipment, Sanchez had received as a Christmas present. For that tryout dive, they visited the Eagles Nest cave system, which is situated within the boundaries of Chassahowitzka Wildlife Management Area, Florida.

Spivey and possibly Sanchez were aware that they had no business attempting such a highly technical cave dive without specific training in cave, decompression, and trimix. The Eagles Nest, also called Lost Sink, is known justifiably as a very advanced, highly technical dive. There is even a huge sign at the water’s edge proclaiming such.

And it’s no secret that such an advanced deep dive demands respect, and training, experience and planning. Especially since the top of the debris cone directly below the system’s rather tight vertical entrance is deeper than the maximum sport diving limit. Anyone wandering in there by accident, would very soon realize the magnitude of their mistake and get the hell out of dodge… well, most would.

But Spivey and Sanchez had broken the rules before and gotten away with it. The pair had, according to records and the later testimony of family and friends, dived several North Florida caves including the Nest, and walked away Scot free. Their luck held.

Like NASA and Morton-Thiokol, Spivey and Sanchez had normalized their deviant behavior, and until Christmas Day 2013, everything was fine. Their predicable surprise was that both father and son drowned.

We all take shortcuts… Certainly I have, and I am sure you have too. If we have done so with dive safety, we’ve been lucky and have gotten away with it… up until this point at any rate.

Because of the regularity of dive fatalities and the metaphorical wake-up whack on the side of the head that these accidents can deliver, stopping the normalization deviance should be a breeze for divers. It should be simple for us to stop taking safety shortcuts. But I don’t think the dive community as a whole is particularly vigilant on that score.

Dr. Petar Denoble, DAN’s research director, writes: “While each accident may be different and some of them occur in an instant, most accidents can be represented as a chain of multiple events that lead to deadly outcome. Removing any link from that chain may change the outcome.”

I’ll put myself out on a limb here and say that if the dive community, especially dive leaders such as training agencies, instructors and other dive pros, could put greater emphasis on the pratfalls and consequences associated with the normalization of deviance, it might help to lessen the unfortunate tendency of some divers to depart from established best practices… We would in essence, be removing a link that shows itself in many chains of error. And we might see diving fatalities shrink: perhaps not to nothing, but at least shrink a little.

We will never change human nature, and never eliminate human error; but we can help to create a culture of responsibility based on a realistic review of what kills divers.


By Steve Lewis

One of the least mysterious things about sidemount diving is how to rig a set of steel primary cylinders so they hang at divers sides as they are supposed to, rather than hanging pendulum-like below them. However, some still struggle to get it anywhere close to right. Perhaps this article will help.

There may be several variations on the basic theme but I’ve found the simple way to rig steel cylinders to hang this way is to break the process of rigging them into a series of simple steps. Now, before explaining things in detail, there are a few assumptions that apply to this method.

Firstly, the primary cylinders are fitted with left and right DIN type valves. Secondly, whatever SM harness you use, it is fitted with loop bungees. Some folks refer to these as “old school” bungees, some call them “Armadillo” bungees because the original Armadillo SM harness used them as standard, and some call them loop bungees. These tips may not work with ring bungees or straight bungees: frankly I have no idea since I use loop bungees exclusively. The third assumption is that you want the orientation of your cylinders to look something like the illustration below.


In it, the diver is able to hold good horizontal trim with her/his cylinders parallel with an imaginary line drawn through their body’s center.

The fourth and final assumption is that the bottom of the cylinders (the part nearest the diver’s bum) are going to be clipped to hardware on the back of the SM harness or somewhere close to the diver’s hip.

A fifth point, not really an assumption, is that as long as tanks with opposing valves are used (i.e. left and right-hand valves) whether the first stages are worn pointing in towards the diver or pointing out to the environment is immaterial.

A simple way to approach tank rigging
Start with the notion that there are several things which will affect a tank’s orientation… and therefore the diver’s also. I find it easiest to get all of these things (let’s call them variables), approximately squared away on dryland and then resolve them one at a time working in shallow water with an observant buddy or one with a GoPro and time to spare.

sidemountTanksnewThe first thing to get sorted is the rigging on both tanks. The clip/boltsnap on the neck of the tank is simply tied onto a small loop of equipment line (3 mm braided poly works fine). The loop needs to be long enough to allow it to fit over the valve and handwheel. This clip is a backup for the loop bungee, so its setup and configuration is probably the simplest thing about rigging sidemount.

It is the placement of the stern (rear) anchor point in relation to the position of the valve… well, the handwheel on the valve, that is a little more complex. I guess we could start anywhere, but I seem to have the best luck, and the shortest gear-tweaking sessions, starting at this point.

First of all, it helps if we understand what challenge we are trying to “fix” with each variable… or what each affects at least.

When we dive sidemount, we want our primary cylinders at our sides, with the handwheels pointing away from our body, and pointing very slightly down towards the sea bed, lake bottom, cave floor, etc.

We want the handwheels oriented this way to make it possible for loop bungees to wrap around the handwheel and stay in place. We can do this by manipulating the location of where the cord with a bolt snap on it is connected to the body of the primary cylinder, in such a way that the natural resting position of the handwheel “knob” is out and down.

Start off by looking at the cylinder from directly above. Think of the handwheel pointing to 12 o’clock on an imaginary (and analog) clock face. Six o’clock is opposite and at 180 degrees away from it, and we want to mark this line. So, take a straight-edge and a marker and draw a line about 20 cm or eight inches long from the bottom of the tank along this six o’clock meridian along the side of each cylinder.

The illustration on the left should make this clearer. It shows a dotted line running along the cylinder at 180-degrees from and opposite to the handwheel. The CAM band is show in red, and the tail (a piece of nylon equipment chord) and the boltsnap or butterfly clip is shown as a solid black line and a small black and red oval at the end of it.

For the vast majority of divers, fixing the stern anchor point at six o’clock (or slightly to the left or right, let’s say five-thirty to seven-thirty) will greatly help orient the bottle and handwheel correctly.

In fact, the best option is to start off with the anchor point at six o’clock for both the left and right-hand cylinders. Fix them in this way, and let’s move on.

Now, note well a couple of provisos. The distance of the CAM band from the bottom of the cylinder is another variable and something we will discuss in a few paragraphs. At this point and as a first step, all we need to do is to find the optimal spot on the clock face to fix the spot where the stern anchor is attached to the cylinder.

For the time-being, we can put the CAM bands three or four fingers width from the bottom shoulder of our cylinder.

OK with that done, we are ready to work on the rest of our tank rigging.

The illustration below shows three more primary variables.

sidemountTanksVARIABLEPoint A is the length of the loop bungee which wraps around the cylinder’s handwheel keeping the top of the tank attached to and aligned with the diver’s shoulder. Making it longer or shorter allows a diver to adjust the position of the valve and cylinder’s top with the diver’s chest and armpit.

If the loop bungee is too long, the result will be a bottle hanging low in the front and higher in the back. If the bungee is too short, the diver will be unable to reach the tank handwheel, and there is a good chance the valve will dig into his or her armpit. This is both uncomfortable, and potentially hazardous since he or she will the unlikely to have the mobility to doff or don the cylinder without help.

Most manufacturers of loop bungees use 6-7mm (1/4-inch) thick shock cord. This thickness is strong enough not to stretch much in water. Bearing this in mind, adjust the length of your loop bungee so that with your arms by your side, and without any tension in it, the end of the loop just pokes out past your bicep. This will need to be fine-tuned for some individuals but this is an OK starting point.

Point B is the length of the tail attaching the cylinder’s bottom to the stern anchor point. (Either a Dring or “door handle” on the diver’s harness, or on the diver’s waistband.) We have already oriented the anchor point to align the handwheels, what’s controlled by making this the cylinder to hang parallel to our lateral line. If the tail is too long and the cylinder will be oriented tail down. Too short and it will be difficult to handle and the tank will sit with its bum pointing up instead of straight back.

The length of this tail WILL need to be adjusted! Do not cut it too short when you first attach it to your CAM band.

Point C is the location of the CAM band or clamp attaching the stern anchor to the cylinder. This is one of the factors influencing the diver’s trim! Moving the CAM band closer to the top of the cylinder will shift weight towards the diver’s bum, while moving it closer to the bottom will shift weight towards the diver’s shoulders/head. So moving the CAM band helps to trim the diver who is either head or bum down… you move the CAM band towards whichever end of the diver is sinking.

I find it much better and quicker to make small adjustments to one variable at a time, and to get it “right” before moving on. Your mileage may vary, but this method works for me.

A few centimeter-adjustment (an inch or so) can radically alter the trim of a tank or the diver. When you move something, make a note of what your did. I also mark the ‘six o’clock line’ on my primary cylinders with hash marks every centimeter or so from the bottom of the tank up about 10 centimeters. This makes fine-tuning my trim easier when I wear thicker or thinner drysuit undies.

There are more subtle issues with getting your sidemount self squared away (hose routing for example), but this should help you improve the way you look and feel in the water.

The value of a buddy with a camera so that you can see exactly what you and your gear looks like in the water, cannot be over-stated… make that happen.


Good luck.


Donating the long-hose in SM…

One of the most commonly asked questions when divers with experience diving the classic North Florida Cave Diving setup (backplate, wing, long hose, etc.), and who are switching to technical sidemount, centers on donating the long hose in an Out of Air (OoA) scenario.

And, here’s the answer I give them.

First let’s look at a common sidemount setup — at least here in North America — which is a configuration with the long hose on the right-side bottle, and a shorter hose to the diver’s left. This configuration almost certainly owes its popularity and its genesis to North American cave divers who converted from wearing doubles to sidemount. These folks almost certainly brought the longhose with them, since the traditional SM rig had NO long hose at all!

OK, so we are considering then, a SM diver with one long hose… on his or her right, very similar to their backmounted cousin.

Now, any discussion of an OoA situation by definition is one about risk management, so first steps are to consider when (if) the requirement to share gas with a buddy becomes necessary. In other words, how likely is it… how often does this happen?

I may have been lucky but after more than a thousand cave dives and several thousand open water decompression dives, I have never been in a situation where gas sharing was required. Certainly never in a panic situation.

Before you start a letter-writing campaign, let’s be clear, I am NOT suggesting it (an OoA situation) does not happen, just that it is a rare occurrence: especially among technically trained and experienced divers. One might argue that it is so unlikely in this community that planning for it should be approached with a different mindset to the one that is taught, but let’s leave that debate for a later date. Instead let’s say that it seems far more likely in a technically trained and practiced team that a team member would realize an “OOA” situation is being APPROACHED rather than suddenly discovering that it has ARRIVED.

In these situations, handing off a regulator would be controlled and simple to manage, almost regardless of which regulator was being breathed from.

Real-world experience tells us that the VAST majority (one might say almost ALL), panicked divers grabbing at working regulators are novices who have been poorly trained, do not follow safe gas management rules, and have poor skills.

However, let’s err on the side of convention and ultra-conservatism and say that OoA scenarios are common enough to require special kit considerations. And let’s look at times during a dive when a team of well-trained, and similarly configured sidemount divers are most likely to experience a mildly emphatic need to donate a regulator. This may help to inform us how best to train/prepare for this type of event.

A list of the most likely times to share gas would certainly begin during the very first stages of a dive. This is the most likely time for a regulator to malfunction, or, if pre-dive tests have been cursory, for things like a leaking second-stage mushroom valve to make its presence known or an incorrectly opened valve to stop delivering gas at depth.

Second on the list would be around the point of “maximum penetration” either approaching the turn-around or immediately following. (For the sake of simplicity, let’s apply the maximum penetration label to an open-water or soft-overhead environment where TIME is often the controlling factor influencing when a dive team turns.)

A third situation is during the final stages of a dive… essentially when a diver switches to his/her decompression gas or during the later stages of a decompression obligation.

It would be beneficial or prudent perhaps, for a diver to PLAN to be breathing from his/her long hose during these periods when the likelihood of needing to donate a regulator is at its highest. It’s not a coincidence that when one follows the method commonly taught to sidemount cave divers (described in an article I wrote for X-Ray Dive magazine last year), this is exactly the case!

Very briefly, the suggested method begins with the diver breathing from the right-hand bottle for one-sixth of the available volume, then switching to the left-hand bottle until one-third of the starting volume has been consumed. At this point, they switch back to their RH bottle and breath IT until a further one-third of its starting volume has been used. Note well that the dive will have been turned about halfway through this second spell breathing from the RH tank. When the RH tank pressure gauge indicates the switch point has been reached (one half of the starting volume gone… one sixth plus one third is one half), the diver switches to their LH cylinder and exits on it.

An added advantage to this method is that there is ALWAYS at LEAST half the starting volume of gas in the RH bottle… the one with the long hose.

Of course, there are a couple of refinements to this method that one can employ.

Firstly, use a long hose on both left and right cylinders. Secondly, attach boltsnaps to regs on the long hose with breakaway fastenings.

Most of all, while there are many alternatives to the methods outlined above, it is worth reminding oneself that putting a lot of effort (and circular debate) about gas-sharing should begin with a full and frank analysis on HOW MANY TIMES GAS SHARING INCIDENTS OCCUR in well-trained, properly equipped teams. The response to this may shock you.

You may also be interested to investigate what actually happens in a panicked OOA situation and how well WHICHEVER technique you have been trained to employ will serve you in that particularly challenging situation.


Hope this helps.

But I can’t be bent, my computer says I did everything right

By Steve Lewis
With thanks to Neal W. Pollock, Ph.D., Research Director, Divers Alert Network

If you are a certified diver, chances are you know a few things at least about decompression stress since part of your initial training (and a lot of what followed in more complex programs hopefully), explained the vagaries of breathing compressed gas underwater.

The issue with diving – at least for this discussion – is that as a diver descends in the water column, he or she has no option but to breathe compressed gas; and the inert gas contained in whatever is being breathed is stored in the diver’s body. This is sometimes called inert gas uptake. At the end of a dive, on the way back to the surface, the process is reversed and is called inert gas elimination or more simply decompression. These two processes are part of every dive… even seemingly benign sport dives to shallow depths for short periods of time. Every dive really is a decompression dive.

Managing inert gas uptake and decompression within safe limits when diving is second only to making sure one has something other than water to breathe. If we “get it wrong” and remain at depth too long, ascend too rapidly, breathe the wrong gas, or simply have a bad-luck day, we run a higher than usual risk of suffering decompression sickness (DCS). Getting bent, the colloquial term for DCS, is a collection of disorders caused by a portion of the inert gas stored in a diver’s body bubbling out of solution too rapidly. The consequences of being bent run the gamut from nausea, fatigue, mild joint pain and dizziness all the way through paralysis and death.

The uptake/elimination cycle is a complex one. For example, it’s believed the speed of inert gas uptake is different (faster) than the speed of inert gas elimination.

Not only are uptake and elimination NOT lineal mirror-images of each other, but several variables are thought to play important roles in the uptake/elimination processes as well. I used the term: “… are thought to play important roles” because the variables – the bio-physical processes at play within a diver’s body – are complex and not completely understood. In a word, the factors governing decompression safety are effectively capricious. We might say with some authority that because of its complexity and variability, DCS is the bête noire of divers and diving. It certainly scares the bejesus out of me.

In the vast majority of recreational dives, the inert gas in question is nitrogen, but when a second inert gas is introduced into the breathing mix – helium for example – a whole new array of complications is unleashed. Diving with two breathing gases – oxygen and nitrogen – presents us decompression challenges: diving with three magnifies the challenge considerably.

An ally in the fight for information about and a better understanding of gas uptake and elimination is the dive computer.

Personal dive computers (PDCs) have evolved astonishingly rapidly in the past 20 years. The current generation does a very good job of tracking the mathematical prediction of inert gas uptake and elimination even when the person wearing the device is diving deep, for long periods of time, and breathing multiple flavors of gas. However, a PDC offers no iron-clad safe-guard that its user will not suffer a DCS episode.

Accepting the ever-present risk of DCS and understanding the erratic character of this risk, is a pre-requisite of becoming a responsible and informed diver, regardless of whether your dives take you to 10 metres or 100 metres; or last for 20 minutes or 200.

A personal dive computer – like any computer big or small – is very good at crunching numbers. It excels at calculating gas uptake based on depth, time and breathing mix; and, with the help of a decompression algorithm, showing users how fast or slow to ascend, where to stop in the water column, and for how long. However, this is all theoretical. Decompression theory is just that; and a decompression algorithm is simply a mathematical model that postulates what happens within a diver’s body when he or she is diving. That’s right, deco theory is woven throughout with guesswork: some of it informed, some not so much so.

The shortcoming of any decompression algorithm and therefore of any dive computer is that the relevance of its calculations to you and me are limited because it cannot adequately account for the numerous biophysical variables particular to us as individual divers. You and I may be similar perhaps, but certainly we are not the same. We can wear the same brand and model of PDC and dive very similar profiles breathing the same flavor of nitrox (or trimix), but the two of us will most certainly on-gas and off-gas at different speeds and with different levels of efficiency. And those differences will vary from day-to-day, dive-to-dive. One of us might get bent while the other is free of any signs or symptoms.

Adding yet another complication is that there are simply dozens of dive computers on the market and several substantially different decompression algorithms at their core… some models of PDC are capable of running more than one algorithm. This makes it close to impossible to give useful suggestions detailing the pros of each and how to work around the cons. Nevertheless, there are a few recommendations that apply to PDC use generally.

Number one, read the user’s manual. Have the computer beside you as you do so and play with it. Get to know what your new tool is capable of and how to activate any bells and whistles it may be fitted with. Learn what button does what and how to access the type of information that is going to help you stay safe on your dive. Absolutely have as an end goal for your “getting to know you” session, understanding what algorithm your computer uses, how to adjust conservatism factors, and the potential effects of more or less conservatism on you and your health.

Number two, use it according to the guidelines in the user manual and whatever common-sense you have been gifted with. In attempts to reset their PDC because of a recent transgression (usually something that came close to getting the user bent), I have witnessed divers pulling out batteries, hanging computers in the water “to decompress,” and even leaving their PDC on the boat for a dive to “cool off.” None of this is a good idea. Seriously.

Number three, all late generation dive computers deliver warnings when their users misbehave. These take the form of audible alarms (bells and buzzers) or visual warnings (flashing colors, symbols or messages). Some combine both. However yours is designed to deliver its warnings, take note of those warnings and modify your behavior accordingly. I once shared a decompression station and an annoyingly long stop with someone whose PDC chirped ceaselessly at him (and anyone else within earshot). He had NOT read the user’s manual and therefore was unable to switch it to any of the three decompression gases being used on the dive. His computer wanted him to return to about 30 metres and stay there for a long, long time.

Number four, understand that a PDC, even one with a four figure price tag, it not a panacea. At most, and following the best possible scenario, all a dive computer can supply its user with is an approximate guide to their decompression status; and a rough guess at their proximity to decompression stress.

Paraphrasing Neal Pollock, a computer, even when used correctly, provides no more than superficial protection from DCS: just the very first-level of information. We need to dig a little deeper into what affects decompression, and understand a little more about our PDC than when to change its battery if we want to mitigate the risks of decompression sickness.

Dr. Pollock, Research Director at Divers Alert Network and a researcher at the Center for Hyperbaric Medicine and Environmental Physiology at Duke University Medical Center, tells us there are more than two dozen factors influencing decompression safety. These include the obvious, such as time and depth, as well as the less obvious and less easily defined and quantified such as epigenetics, atmospheric pressure, and pre-dive exercise.

Essentially, Pollock’s research underscores the difficulty of producing a “magic silver bullet” capable of protecting us completely from DCS. He also suggests that often divers who suffer DCS look for some way to shift blame. They tell us their incident was “unearned.” “Hey, I did everything right… exactly the same as many times before.” They moan because their computer did not warn them. In fact, one often hears a diver express confusion because their dive computer did not get bent and they did.

He says if we fail to recognize errors in our behavior, our pre-dive preparations, or the influence of our personal makeup and fitness to dive, “and we refuse to take personal responsibility,” the learning process breaks down.

Pollock explains that many of us focus on only a small part of the overall picture regarding decompression safety. He uses the example of hydration. Divers routinely blame poor hydration for causing their DCS, but few have a realistic handle on what constitutes good hydration, and fewer yet on the many other factors that contribute to deco stress.

“Proper hydration may play a role in decompression safety, but throwing back a half-litre of water immediately before diving does nothing except make you pee,” he explains. “The “hydration” goes right through without any appreciable effect.”

So where does this leave you and me?

If your diving exposures are mild, you are certified to use and indeed use the appropriate nitrox for your dives, you behave responsibly and cautiously, and follow the best practices suggested by organizations such as DAN, chances are good you will never experience DCS.

If your diving is a touch more radical, and you routinely conduct staged decompression dives, the advice is to dive especially conservatively. Research and understand all the many factors that may have an impact on your safety, and plan accordingly.

Most of all, take responsibility for your actions and don’t make a challenge out of who can get out of the water fastest. Better to enjoy a slightly delayed post-dive beverage with your mates than spend hours in the chamber wondering why it is you’re bent but your computer isn’t.

I wanna make a case for unsweetened tea

If I first tell you that I’m an expat Brit, it will probably come as no surprise if I also share with you that I enjoy a cup of tea. A few shots of strong espresso in a bowl of hot milk is my morning drink, but tea is on the menu for most of the rest of the day. Perhaps less easy to fit into the ethnic stereotyping is the way I prefer my tea made. That preference is not hot with milk and sugar, but black with lemon, cold and unsweetened. And if we want to assume another level of stereotyping, you might ask yourself how I developed a taste for a drink that is a favorite in the Southern States but difficult to find most any place else, especially where I live in rural Canada.

By the way, the answer to the question above would be scuba diving. I like to drink unsweet tea anytime I can lay hands on it, but in particular I like to drink it when I am diving. Now I should also explain that I drink a lot of water when diving or otherwise. On a normal day, my water intake is around two to two and a half litres. When I am diving, I throw down at least that much. However, I also like to drink tea… probably a litre or more of it given the chance. My guess is that I “caught” the habit hanging out in North Florida’s Cave Country.

Now just in case you are reading this and saying quietly to yourself: “Guy’s an idiot. Tea is a serious diuretic and divers should steer away from it,” give me a couple more minutes.

And by the way, if you ARE thinking that, you’re not alone. I was recently on a dive boat (an excellent live-aboard working out of the Florida Keys). Always open for suggestions and customer feedback, one of the owners asked what I would change about their operations. I suggested their soda gun have a button for unsweetened tea added. She looked at me with a smile and explained that tea being “the most powerful diuretic known” I would not be seeing it on the menu for her divers anytime soon.

I resisted the temptation to argue. For example, I resisted the temptation to point out the boat’s soda offerings included: cola, and root beer; both of which have serious dietary side-effects from ingredients not to be found in tea. I also chose to not point out that there was a huge canteen of coffee on the galley counter below decks… surely if tea is diuretic, that must be too. Right? And thankfully, and most of all, I resisted the temptation to cry: “Bullshit.” Because bullshit it is.

Here are some facts about tea.

Tea is, at worst, mildly diuretic; with the emphasis on mildly. While you may poo-poo the veracity and question the bias of any study I care to cite here, data – and not some bullshit hearsay from a dubiously researched diving manual – indicates that everyday consumption of tea (hot or otherwise) does not produce a negative diuretic effect unless the amount of tea consumed at one sitting contains more than 300mg of caffeine. Since the average cuppa contains around 50mg, you’d have to drink about 1.5 litres of tea in one sitting to ingest this level of caffeine. That, my friends, would take some serious guzzling.

It may be worth noting that the British Dietetic Association has suggested tea can be used to supplement normal water consumption! Nothing there about tea being counter-indicated for good hydration… the opposite in fact. The BDA report went on to state that “the style of tea and coffee and the amounts we drink in the UK are unlikely to have a negative effect [on hydration]”. I think we are safe to apply the same logic anywhere else in the world.

A clinical study published by the British Tea Advisory Panel (admittedly a potentially biased source) stated that a cup of tea can be just as good as a glass of water at keeping your body hydrated. It explained that four to eight cups of tea consumed throughout the day, is thirst quenching “without any diuretic side-effects.” Now, I am willing to squint a little at one or two of those assumptions without adding some provisos but it’s interesting nevertheless.

In addition, the Harvard School of Public Health rates tea as one of the healthiest beverages. Tea contains essential nutrients that are being studied for their value in possibly preventing heart disease and diabetes. For instance, brewed tea is rich in free-radical fighting antioxidants.

Unsweetened ice tea is also naturally low in calories. A 16-ounce glass of unsweetened ice tea (that’s a little less than half a litre) will deliver about three calories. The same volume of cola contains about 180 calories all of which come from sugar.

Now you are free to drink whatever you want. And if I am on your boat, I will follow your rules and allow you to live by whatever odd dietary foibles you may have. But, please get something straight, unsweetened iced tea is NOT a serious diuretic and in fact may encourage divers who have an issue drinking a healthy dose of water to actually better hydrate.

Thanks for your time!

Anyone for a cuppa?


One of my students (in a sidemount clinic) suggested this might be helpful if more widely circulated. I see many sidemount divers — newbies and “experienced” — working ad-hoc when it comes to kitting up. If that works for you, great. I seem to have better luck, and seem to get the job done faster, following a set procedure. Here is the one I use.

Sidemount rigging… the easy way to get all that gear on without forgetting anything!

This is essentially an “assembly checklist” for diving two primary bottles configured correctly with opposing handwheels and rigged for sidemount diving.

  1. If gas in both cylinders has not been analysed, do so and mark MOD of mix on duct tape applied to neck of primary cylinder making sure it conforms to dive plan and is OK to surface breathe.
  2. If gas has already been analysed and MOD marked, check it conforms to dive plan and is OK to surface breathe.
    1. MOD for both cylinders should be the same give or take one metre or less
  3. Connect regulator with long hose to right-hand cylinder.
  4. Inspect hoses, crimps, exterior of first and second stages, and house the long hose in tank bands.
  5. Pressurize (turn handwheel on), confirm starting pressure / volume is correct according to dive plan.
  6. Turn handwheel off. Watch SPG for any fall in pressure.
  7. Repeat procedure for connecting left-hand regulator (necklace) to left-hand cylinder noting that starting pressure in both cylinders should be approximately equal.
  8. Position cylinders in the most convenient spot for you to stand, sit, kneel or squat between them.
  9. Don SM harness and tighten shoulder straps, chest and crotch straps.
  10. Get between cylinders and get ready to put them on.


  1. Clip nose bolt snap to top D-ring
  2. Clip anchor bolt or butterfly snap to butt plate rail
  3. Put loop bungee over handwheel
  4. Connect LP inflator to wing and test
  5. Route regulator hose up left side and around neck passing necklace bungee over head
  6. Inspect mouthpiece for holes, cable tie in place and tight, and no foreign objects
  7. Begin to wet-breathe regulator
  8. Watch for SPG pressure drop and turn handwheel until valve is fully open



  1. Clip nose bolt snap to top D-ring
  2. Clip anchor bolt or butterfly snap to butt plate rail
  3. Connect LP inflator to drysuit routing hose under harness and over chest strap… test
  4. Put loop bungee over handwheel
  5. Pull sufficient length of long hose from retainers (two “clicks”), and route regulator hose across chest, and around neck
  6. Inspect mouthpiece for holes, cable tie in place and tight, and no foreign objects
  7. Begin to wet-breathe regulator
  8. Watch for SPG pressure drop and turn handwheel until valve is fully open
  9. Clip regulator off to bottom D-ring on right shoulder.


Finish pre-dive checks and go diving.

SMS75 from Hollis…

Thoughts about the latest sidemount harness from the folks who brought us the SMS100 and SMS50


Last November I had an opportunity to dive the prototype of a new sidemount harness being developed by Hollis. Already a SMS100 and SMS50 user, I was interested to see what the company’s “mid-range” design could do that the 100 and 50 could not.

That November introduction involved diving the Hollis rig at Jackson Blue Spring in Florida. I enjoyed diving it and immediately phoned my contacts at Hollis. I explained the 75 was almost exactly what I wanted from a sidemount harness. I wanted one to dive in a variety of conditions to test if my original assessment was correct. I had to wait a while. Quite a while and when my first shipment of SMS75s arrived from Hollis a couple of weeks ago, I was extremely happy to finally have units in-hand.

Not only did I had pre-orders from students who were signed up for sidemount courses, I was even more excited to get my personal unit in the water for proper testing outside a cave environment to see how it fared in colder water and lumpier surface conditions.

I’ve never been disappointed with kit from Hollis. My experience with the company’s wings, fins, instruments, DSMBs, reels and so on has been really positive. It may cost a little more to design and produce gear that’s going to last ages, but I hate having things break because of cheap components and crappy quality assurance controls. I cannot say price is never an issue, but I am willing to fork out a bit more cash in the hope of avoiding the sort of disappointment that inevitably follows using shoddy kit of any sort.

With that said, right out of the box, the SMS75 is impressive. As with the SMS100 and its tiny travel cousin the SMS50, the 75 looks like professional-grade gear, and in a side-by-side comparison with other units in my personal dive locker, the Hollis stands out. If you know power tools, I think a fair comparison is comparing a heavy-duty DeWalt or Milwaukee cordless drill with a $29.99 special from a no-name manufacturer only doing business on eBay. Anyhow, built from rugged 1000D Cordura, the SMS75 looks tough enough to take a beating, and the finishing is excellent… no hanging threads, gaping or marginal seams or dodgy sewing.

As well as the build quality, the SMS75 has several design features that result from outside-the-box thinking. These deliver benefits that are easy to appreciate and that make rigging simply and comfortable with the least possible fuss.

The traditional habit of taking the shoulder harness and anchoring it behind a diver’s hip is a throwback to the design restraints of the North Florida Cave Diver’s backplate and wing setup. When faced with the challenge of taming a set of double steel back-mounted cylinders, legend has it that Greg Flannigan and Bill Main solved the issue with a continuous length of two-inch webbing and a purloined Florida Department of Transportation road sign. Fixing the over-the-shoulder harness was easily done by threading it through the backplate and almost every backplate manufacturer almost thirty years later, uses the same method. Most sidemount manufactures – including Hollis with their SMS100 and 50 – follow suit. Trouble is that this routing for a harness while reasonably stable, is not the most comfortable nor does it make things easy when trying to doff and don kit.

With input from a couple of Hollis Ambassadors, Nick Hollis, himself a sidemount diver, Edd Sorenson and other hard-core cave divers, the shoulder harness on the SMS75 is different. It attaches to the waistband away from the diver’s lower back and close to his or her side or front effectively creating in combo with the unit’s crotch strap, a stable three-point anchor system.

Not having two-inch webbing biting into your armpits may take some divers a few tries to get used to but for me at least, it felt immediately more comfortable. Once adjusted it also felt more stable, but there is a temptation to over tighten the shoulder straps which pulls the waistband out of anything approaching alignment. The trick is to get it snug and then let gravity and the crotch strap do its work.

Another obvious innovation is the trapezoidal-shaped buoyancy cell on the SMS75. Unlike a traditional wing, it puts most lift around the diver’s hips and none at all on the shoulders. The traditional wing used in tandem with an aluminum or steel backplate spreads buoyant lift more or less equally between the shoulders and hips. For the typical sidemount diver who wishes to attain a horizontal trim, a traditional wing, or an integrated buoyancy cell delivering any appreciable lift at the shoulders will create a challenge: this type of cell tends to float the diver in a heads-up orientation.

The benefit is that right from the first couple of seconds in the water, a diver using the SMS75 trims out at or close to horizontal. While some other sidemount systems often require modifications or trim-weights on the diver’s shoulders, I’ve found that small changes in the tank cam bands is all the adjustment necessary to get a diver “squared away.”

I’ve long been a fan of the more traditional loop bungee (AKA Armadillo or Old School bungee) over the straight bungee or ring bungee. I find it keeps the neck of the primary cylinders under control and helps to set up their orientation where it’s supposed to be (at the diver’s side) and at an angle that is correct (parallel to the diver’s lateral line). The SMS75 ships with loop bungees, and this once again saves time getting the system set up ready for diving.

One last innovation. The SMS75 features ‘reversed inflator/dump:’ the OPV/Dump is located on the top of the unit behind the diver’s head while the inflator is protected and tucked away on the diver’s left hip with the working end of the hose and its inflation valve located on the left breast and held in place by small-diameter shock chord.

For those used to finding the draw string for the dump close to their hip – or a little lower – it will take a few dives to unlearn the old muscle memory and relearn a new one… but in my opinion, the ubiquitous plastic elbow fitting is the weak spot of almost all buoyancy devices. Having it tucked away and out of the way is worth a few minutes learning a “new trick.”

In two words: It’s magic.

There are several good sidemount harnesses on the market. They each have pros and cons, and frankly I have no issues diving many of them because they work and are fun to dive. However, I teach sidemount and one of the toughest “asks” of any instructor is getting the student and his or her harness to fit together like a hand and glove. You can get there with almost any unit from a reputable manufacturer, but it takes some work. In the most extreme cases, that work involves scissors, a grommet punch, and lots of cable-ties or an industrial sewing machine. In the easiest, there is always some modifications to be done.

The SMS75 is an exception. This past weekend, I worked with three divers wearing SMS75s and had them all just about done inside of an hour of surface and in-water time.

Hey, I am a sidemount diver, so of course there are two things I would change, even on the SMS75. I’d like the double ring clip attached to the center of the butt plate to have slightly larger clip-off points, and I’d also like a second set of door handles either side of the butt plate… but neither is going to stop me from diving it.

The marketing message from Hollis tells us:

“The SMS75 is an evolution from years of sidemount development, which started with the SMS100. A product that has been copied, modified and a benchmark for technical sidemount for years. Even more popular has been the lightweight SMS50 line. These two have taken sidemount mainstream and the building blocks this new harness. While it will cater more to hard-core cave divers, SMS75 was created to handle all environments.”

All good stuff, understandable, and not full of bullshit. Most of the OC diving I do these days is in overhead environments – caves or wrecks – and the choice to dive this style of kit configuration, after more than 18 years diving traditional backmounted doubles, was based on both lifestyle AND mission specific criteria. Sidemount is not a panacea. Nothing is. It is simply an extremely flexible and useful tool that works for many different types of diving.

I think it’s fair to say that with the SMS100 and the SMS50, Hollis helped to convert many divers to “going sidemount.” Hollis was a relative late-comer to sidemount diving, but they listened to community feedback and in just a few years, have become one of the manufactures who are front and center in the sidemount market. With the SMS75, its divability out of the box, the ease with which it can be configured, and the range of diving that I feel it’s suited for, Hollis definitely has a winner.

Important to note that the SMS75 is not revolutionary. It is not going to turn a bad diver into Superman or Wonder Woman and it does not have a special switch that will suddenly fix an OOA problem. However, it is a fine piece of kit. Well designed, balanced, well-made, easy to use, and reasonably priced.

And while it’s unlikely to bring peace to the Middle East, it certainly has the ability to bring sidemount diving within the grasp of a lot more recreational and technical divers. And if you haven’t tried it, give it a shot… you might like it.


As an aside, the SMS75 is rated for 40 pounds of lift (enough to float about 18 kilos). The smaller SMS50 is rated at 23 and the SMS100 is credited with a touch more than 50 pounds lift. The SMS75 is available in three sizes: SM/MD, LG/XL and XXL and the system weighs seven pounds. It also ships with two cam bands, SS bolt snaps and enough equipment line to rig two primary cylinders. Suggested retail is $695US.


So many lessons to learn…

Why can’t we buy gear at North American Dive Shows?

I just returned from a trip that included visits to dive shows in Paris and Dusseldorf. It was a working trip and a bloody hard slog at times. Several days after getting back to North America, I am still waiting for my checked baggage, with my truck keys and shaving kit packed inside, to arrive. But despite all, the trip was worth the effort; if for nothing else for the lessons it taught me about the dive industry… or at least the portion of it that deals with running dive shows.

Perhaps the biggest and most obvious difference between European shows and those in North America is that punters in Europe can buy stuff. At Salon de la Plongee and BOOT Show, people were buying drysuits, rebreathers, regulators, BCDs, wings and backplates… and vacations! Imagine that. Both the Paris and Dusseldorf shows (and a couple of English shows I’ve attended in the past) seemed to be busier too. Is attendance density related to the ability for consumer to purchase kit? I suspect this is the case.

Someone once explained that you cannot buy dive gear at shows in North America because of liability issues. You can place an order at a stand and have it shipped to you later, but you can’t buy it on the spot and stuff it in your backpack. Anyone else think this is silly? It makes zero sense to me and the liability argument must surely pre-date internet purchases. After all, I can buy a rebreather off eBay no questions asked… surely there’s a greater weight of liability buying something that way than face-to-face with a manufacturer at a dive show.

Could be entirely unrelated but another difference in Europe is the age and general appearance of the punters walking the show… the demographics actually. The average attendee is younger. It is not just that there seem to be a lot more 30-somethings in the audience, but many have their children with them… diving seemed to be more of a family event in France and Germany. There were even dive-related events and displays specifically targeted at future bubble blowers.

I have seen campaigns over here that make a big thing out of diving bringing out the kid in all of us, but we ban kids from coming into the largest dive show on the continent!

There’s a lot wrong with the way North Americans package and market diving. Letting punters bring their kids and allowing them to buy at shows is not going to fix much, perhaps, but good lord, it might help surely.

Not sure if anyone from DEMA is listening to any of this, but if you are, take note. Two free marketing tips: Include Consumers and Future Consumers in your tired worn out show.

The final word from my new book…

This has been a poor year for diver deaths. I have just wrapped up a book called Staying Alive and it’s about risk management for divers… I started it because of a couple of regrettable incidents and as I finished it three months later, more deaths. The book is scheduled for launch next month from Amazon and CreateSpace. Here are my closing remarks.

Perception of risk changes over time. The more successful we are at beating the odds, the less risky we take our behavior to be; and of course, the opposite may be true. Too often, luck reinforces bad decisions and dilutes fear, and fear is surely part of the apparatus, our personal filter, for risk management. We each must understand that because someone surfaces from a dive with a smile on their face, it does not mean they follow a good risk management process or that their behavior is not risky. It is impossible to measure a negative. Vigilance is required.

I am sitting in my office wrapping up this project. There is snow on the ground outside and I will soon have to pack and get ready to fly to Europe and go to yet another interesting and very big dive show. Perhaps I should feel happy, but I do not: I am sad.

Yesterday evening I got news that a father and son (a boy of 15 who had earned no level of scuba certification at all) had both drowned in the Eagles Nest Cave, an advanced-level North Florida system considered a challenge to certified and experienced trimix cave divers. They were, according to family, testing out new gear the kid had been given for Christmas. What on earth were they thinking: what was the father thinking as he died? Last week, two more technical divers perished. One in the Red Sea and one in the caves of Mexico. I knew them both. One much better than the other but both were nice guys; both were experienced, and unlike the father/son combination who died in a spot where neither belonged, both of last week’s victims were what one would call careful divers.

Fatal dive accidents frequently have multiple and complex, often interconnected, root causes. While each accident has unique qualities about it – in part because of the individuals involved – most accidents can be characterized as a chain of small events that lead to disaster.
This chain of events very often starts with a minor challenge – a failure in communications, a broken strap – and one event meshes with a deficiency or mistake elsewhere and triggers something even more serious, and this in turn results in escalating calamities until the house of cards has fallen down completely. To stay on top of things, technical divers need to become pretty slick at recognizing problems early, preventing a chain reaction, and thereby avoiding a one-way ride to calamity. Often something as simple as calling a dive early, before anyone gets close to the edge, can change the outcome radically and turn a potentially nasty epiphany into a positive learning experience.

Gareth Lock, who was kind enough to write the foreword for this book, is a Royal Air Force officer with a background in risk analysis and management. In his writings and presentations, he shares with us a refreshingly analytical view of dive accidents.

He and I arrive at a similar destination via quite different analytical pathways. Based on his background in the military, he uses what he calls the HFACS Dive model (pronounced H – FACS-D). His analysis and methods are based on the Human Factors Analysis and Classification System framework developed by Dr. Douglas Wiegmann and Dr. Scott Shappell of the United States Navy to identify why accidents happen and how to reduce their impact and frequency. Gareth suggests that for a dive accident to occur, several contributing factors have to align. These factors may include organizational influence, unsafe supervision, a pre-condition for unsafe acts, and unsafe acts themselves.

I believe the factors, the triggers, that lead to deaths like the recent ones in a Florida cave, the Red Sea, and Mexico are more personal, more within our grasp. The eight triggers identified back in the 1990s: Attitude, Knowledge, Training, Gas Supply, Gas Toxicity, Exposure, Equipment and Operations, provide divers with a laundry list of potential dangers.

Gareth points out with some clarity, that people ‘get away’ with diving ‘successfully’ when there are errors at every level in his HFACS model: they simply did not align that day. “And that,” he tells us. “Reinforces bad decisions and creates diver complacency.”

One has to agree with him regardless of how or why you feel divers are dying so frequently. It seems that ignoring just one of the eight risk triggers may be enough to begin a series of events that end in death: it may take two or three, and a lucky diver may get away with ignoring four or five without an incident. Life is not fair that way.

Finally, Gareth reminds us: “It is easy to blame a person, when the system is actually at fault.”
I believe too that we are sometimes too quick to blame the individual and often do not trace the mistakes made back to their “systemic” roots, but sometimes all the fault does rest with one person. The system did its best and the best is all we can expect of anything outside of a nanny state. In some instances, the buck comes to a full stop up against the victim’s attitude, their ignorance, their lack of training, their history of flaunting the rules, their willingness to gamble with the odds.

Every day you and I, indeed the whole diving community, are faced with a dilemma: error of omission or error of commission. In cases where we know someone is pushing their luck, do we mind our own business, remain quiet and watch as they hurt themselves or their dive buddies; or do we speak out? If we are part of a system that Gareth and others say needs fixing, do we have the tools to carry out the repairs? Do we even know what to fix and where to start? Can we make a difference?

There’s a kid throwing starfish back into the sea as the tide recedes. A guy walks up and asks him what he’s up to. “Saving lives,” he explains. “The tide is going out and these starfish will die on the beach, so I’m throwing them back in.” The man laughs and tells the kid that the beach is miles long and that there are hundreds, probably thousands of stranded starfish. He tells the kid he can’t save them all. The kid stops what he’s doing, looks at the guy, looks up at the sky, and back out at the ocean. He bends down, picks up another starfish and throws it as far out to sea as he can. “Saved that one!”

My hope is that through all this effort, I may just get one person to think twice before starting a dive with a faulty oxygen cell, or breathing a gas that hasn’t been analyzed, or dismissing a buddy’s suggestion that today is not a good day to go diving or taking an unqualified diver to a trimix depth cave to test new gear. Help me save a starfish.

New Sidemount Options

I rarely write reviews of kit; however, I had an opportunity to dive two new sidemount harnesses last week. One a prototype of the HOG/EDGE SM system; the other the new SMS75 harness from Hollis. I wanted to share first impressions since my experience with the out-of-the-box usability of most SM rigs is one flavored with frustration and compromise. Both of these new offerings show some promise in my opinion, and both suited me and my style of diving well.

For the record, I was diving in Jackson Blue (a North Florida cave) wearing an O’Three 1-100 drysuit and using a borrowed set of Worthington low-pressure 17 litre / 108 cft cylinders, and carrying an aluminum 40 cft cylinder for decompression gas. On the off-chance that you are not familiar with these steel cylinders, each has a surface empty weight of a little more than 20 kilos.

First, the Hollis SMS75. I’ve been waiting for a chance to see and dive this rig since being told about its development earlier this year. As with all the Hollis gear that I’ve used over the years, the SMS75 is well-built and looks like it can take abuse, which for a sidemount rig is essential. The basic design at first glance looks similar to the SMS50 but there are several key differences. To begin with, more buoyancy with the emphasis on getting the diver’s hips and arse up without resorting to sticking trim weights on the shoulders. The rated lift provided is stated as 45 pounds (about 200 Newtons or 20 kilos). I have not tested that rating but I was near bladder capacity wearing the tank package described above in fresh water.

Next is the harness. The shoulder harness is connected to the waist band webbing via two adjustable retaining buckles rather than disappearing under the armpits and attaching somewhere uncomfortable close to the diver’s back. This design is more stable and delivers better control and is essentially a rethink of the “classic” steel or aluminum BP harness routing that I find cuts into my armpits. While most SM designers have adopted a follow the leader approach, it’s refreshing to see that both Hollis and HOG have given this aspect of their rigs some thought.

Another difference between the SMS50 and the 75 is that the SMS75 comes with “old school” bungees (also known as armadillo style bungees). This style of bungee (when properly adjusted) has the advantage of keeping the top of a diver’s primary bottles where they belong and not sliding around shifting balance points as the diver reorients him or herself to navigate restrictions.

The final chance is that the inflation hose is flexible rubber with an oval cross-section and not the hard, inflexible circular trash used on many rigs… including other Hollis rigs.

Other hardware seemed adequate and perfectly serviceable… without any need to resort to scissors and duct-tape.

One potential drawback of the Hollis system is that I’ve been told it’s available in only one size. It fitted me perfectly, but I’m more or less “stock” size (180 cm tall).

The prototype HOG rig has been back and forward between the workshop, drafting table and test group for more than a year, and is finally due for its official launch around Christmas 2013. Because of this, it’s not really practical to offer anything close to a blow-by-blow of the system I dived, except to touch on some design features that I believe will make it to the final product.

Harness innovations are similar to the Hollis SMS75 which is due in great part to the fact that Edd Sorenson consulted for both companies — and in fact dives regularly with BOSS HOG, Chris Richardson. The lift that HOG is aiming for is a few pounds/kilos/tens of Newtons more than the Hollis, and the unit I used delivered about 55 pounds of lift, again focused on the lower back and hips. The shoulder dump was pouched on the demo/prototype so I was obliged to rotate and use the LP inflator unit to dump gas. This made for a couple of less than stellar moments during a couple of days use, but obviously should not be a concern on the “real thing.”

Again, similar to the SMS75, the HOG unit had the smaller, higher profile Tech “door handles” on a wider than normal butt plate. This positions the anchor points for the primary cylinders close to the top of a diver’s hip bone rather than a few centimeters lower down and closer to the spine. This is a good option for most of us but I can see it presenting a mildly annoying cylinder trim challenge to those who dive aluminum cylinders.

The HOG unit has adjustable crimping bungees to control the distribution of lift… a little… and also has a smooth replaceable cover over the whole of the buoyancy cell. Jury still out on this. It’s “required” because of the bladderless construction of the HOG wing, and did not get in my way. I simply reserve judgement until I see the final product.

Both the HOG and Hollis were fitted with a Y-style crotch strap rather than the single 2-inch webbing “be careful of the family jewels” option that most every other SM unit uses. I love this type of harness and find it way more comfy and the better option for being pulled by a scooter. Not sure if this will be the default with full production units. If it’s an option, I will ask for it.

Overall, BOTH these units seem VERY well-designed and functional. The SMS is useable out of the box if the unit I used is any indication. The HOG has a couple of “minor edits” before full production for an end-of-year delivery… but Chris tells me they will be done.

My final take is that I will be replacing my existing SM units (ones loaned to students in workshops and clinics) with both the HOG and SMS75, and I while I will keep my SMS50 for a light travel unit, my personal SM rigs will be replaced with a HOG and an SMS75 before I get back in a cave (or wreck) in open-circuit gear.


USING ADDITIONAL REDUNDANCY: the maligned and misunderstood pony bottle

This is a short extract from a book on risk management that we hope to have finished next month.


I would guess that most dive instructors, especially those who teach technical programs, get regular requests from divers to explain how to “use” a pony bottle, how to configure it so it’s not in the way, and which size pony bottle is “right” for them.
These are great questions because any diver who intends to dive deeper than 30 metres /100 feet should carry a redundant source of gas. A dive buddy is supposed to represent the first line of backup, and a well-trained and well-practiced buddy is a great resource in the event of some major gas emergency. However, the best strategy is that whenever practical strive to have a backup for your backup. In this regard, redundant air via a redundant delivery system offers a huge cushion.
The question of size is perhaps the first question to answer because how to rig and use a pony bottle depends to a large extent on its size.
When we consider using a pony bottle as a bailout or as a backup in the event of a massive gas failure with our “primary system” (the normal tank and regulator), we factor in a full minute at maximum depth to get things sorted and to gather our wits before starting the ascent. With this in mind, let’s revisit the table for SAC adjusted for depth. Since we are still talking about recreational sport diving, the limit for maximum depth is around 40 metres or 132 feet. The ambient pressure at this depth is five bar or ata and therefore the average per minute consumption will be 70 litres or 2.5 cubic feet.

Let’s also apply a realistic dive factor. Since a pony bottle is only deployed in times of stress, we need to use a DF for that first minute that reflects high-stress. The norm for this application is a DF of 2.5, which translates into 175 litres or 6.25 cubic feet for that critical first minute!
(If at this point you are beginning to question the veracity of ads extoling the virtues of those tiny emergency cylinders of “spare” compressed air, please read on.)
After the first minute, we calculate a normal ascent rate (9 metres or 30 feet per minute) up to a safety stop. That journey – about 35 metres/ 117 feet – will take about four minutes. Once again, to help simplify the calculations, we use the ambient pressure at the midpoint between maximum depth and the safety stop, which in this case will be 3.22 bar or ata. We also drop the DF to 2.0. So we have ascent time X SAC X ambient pressure X DF, which equals 360 litres or about 13 cubic feet of gas.
Now for the safety stop. Even when a dive is within the no decompression limits, there is a strong suggestion from most experts that a five-minute stop is indicated after a dive to maximum depth. So the consumption for a five-minute stop at 4.5 metres or 15 feet with a mild DF of 1.2 adds up to a total of 122 litres or 4.35 cubic feet. Finally we have to factor in a little gas for the last part of the ascent to the surface. Therefore, the best estimate is that a controlled ascent following an emergency at depth will require at least 680 litres or close to 25 cubic feet of breathable gas!
It’s the considered opinion of most divers who have experienced a real gas emergency at depth in real-world dive conditions that these numbers are neither exaggerated nor inflated. When something bad happens at great depth, there is no such thing as a plan that is too conservative or too careful. The risks of drowning, embolism, decompression sickness and various other ailments that can result from stark panic and ballistic ascents are very real and totally unforgiving. The alternative to a controlled normal ascent are simply not worth considering.
Clearly then, the “right” pony is one that holds at least 680 litres or 25 cubic feet. Because of its general usefulness, buoyancy characteristics, ease of deployment, and attractive cost compared to smaller tanks, many divers invest in an aluminum 40 (nominal capacity 40 cubic feet / 1200 litres) as the best “emergency” pony bottle.
Two final words on the topic of pony bottles before we move on to gas volume management for more advanced diving. The gas carried in a pony bottle is contingency gas. It should never be factored into the gas volume requirements for a dive. It is there for emergency use only. If the dive plan calls for more gas than can be carried in a regular primary scuba cylinder – an aluminum 80 for example – then the total kit configuration for the dive needs to be reconsidered and calls for an additional primary cylinder or a high-volume primary cylinder such as a steel 15 litre / 120 cubic-foot tank.
A bailout/pony bottle is useless if it does not deliver breathable gas faultlessly. The valve, regulator and SPG must be tested before every dive. Do not take for granted that it is filled and in working order. Analyze and label its contents, check the pressure and wet-breathe the regulator at the start of each dive.
Let’s leave this topic with one last thought. As we were editing this chapter, I read about yet another incident where a diver “ran out of air.” This time a pair of brothers and a friend were hunting crayfish in about 30 metres / 100 feet of water off the coast of New Zealand. Calm conditions at a site familiar to all three divers. Describing the victim, his brother said: He was a competent diver with several years’ experience.

I would suggest an edit… a small change but something that I hope will speak volumes to you. He was USUALLY a competent diver, but not this time. Even several years’ experience cannot compensate for serious oversight.
Plan your dive, dive your plan.

Self-Assessment: an antidote to complacency?

Cleaning out old files and finding a copy of my original dive-plan template – something my buddies and I used for several years when we first started to do deep mix dives – I remember why we scrapped it and drew up a new one: It’s missing an important element.

If memory serves, the error was pointed out by Bret Gilliam. At that time – around 1996/97 – Bret was president of Technical Diving International (TDI) and he was gathering information for student manuals and asking members to contribute things like teaching notes, learning goals, and so on. Among the various bits and pieces I contributed was a spreadsheet template of the dive plan my buddies and I were using, and that I was also teaching students to use.

“It’s good but you’re missing something…” he told me after looking it over for a few minutes. “Something critical.”

I checked it a couple more times and to my eyes the plan looked pretty comprehensive and exhaustive. I told him I could not see what was wrong with it.

“There’s nothing in it about conducting any level of self-assessment before you jump into the water,” he said. “Don’t you think that’s worthy of a line or two?”

There is a well-established maxim that tells anyone who’s listening that complacency kills experienced divers. Checklists and Dive Plans are intended as a good first-line of defence against that sort of complacency. They are intended to counter human nature and swing attention back to things that it’s easy for divers, even very experienced ones, to take for granted and overlook. For instance, I’ve seen divers forget or simply not bother to conduct a positive/negative check after refilling a diluent bottle on their rebreather. A checklist can serve to remind someone with this level of complacency not to be a Muppet.  But, as Gilliam pointed out to me, the most complete, comprehensive and meticulous dive plan cannot prevent things going horribly wrong if the folks executing it aren’t as present-and-correct and as ready as their equipment to do the dive.

Self-assessment is now included in the pre-dive checks for all TDI and PSAI courses, but like the requirement to analyze and mark EVERY bottle of gas, or pre-breathe EVERY regulator – or any of the other listed items on a checklist or dive plan – it is entirely self-policed, and quickly becomes worthless if any one member of a dive team shortcuts that “policing operation.”

The process is simple enough. You ask yourself a couple of easy-to-answer questions and you answer them honestly. Better yet, when the dive leader has completed her self-assessment, she should check with everyone on the team to make sure they all “passed” the self-assessment check.

When we dive – even on those dives that seem like a simple bimble around in shallow water – we must ask ourselves if our plans account for any and all hazards. For the purposes of providing a realistic answer, a hazard in the case of diving is any agent or situation posing a credible level of threat to our life, health and property, those of any team member, or the environment in which we intend to dive.

When we make a self-assessment, that assessed risk includes things that are not visible or readily apparent to our buddies. One is our personal level of comfort.

To check this is the case and that our planned dive is within our comfort-zone, ask: Considering ALL the risks associated with the dive as planned, do I find them acceptable? Does the plan cope with things, events, which have some significant probability of occurrence during that dive? Rottweilers hit the fan and precisely when and how depends on circumstances that may not be predicable. Does the plan make allowance for this and am I comfortable if it does not?

Recreational divers, even those engaged in kick-ass technical dives, are under no contract and are not protected by legislation. Each of us is responsible for our safety and well-being, and – to some extent through enlightened self-interest and the tenets of friendship – with that of our buddies. Honest answers to these questions will help keep us safe and should be asked before every dive; no matter how simple and inconsequential the dive seems.

In addition, there are several other questions we might ask ourselves as part of the “self-assessment” process that should be carried out long before we pull on a drysuit. They concern personal health. We need to ask if we are comfortable with: our personal heart health; are we free from angina, epilepsy, diabetes, asthma, dehydration, and fatigue? Is our cardio and physical fitness up to the stress of the dive as planned? Do we have adequate strength to do the dive as planned? Have we learned and practiced the critical safety skills required on this dive as planned? Are we diving drunk, with a hangover or stoned? Are we physically and mentally ready to do the dive as planned and if something hits a fan while we are down there, are we ready to deal with it appropriately?

It may seem a little odd, but self-assessment should also ask: Do we believe in our buddy’s abilities and do we feel they have the skills and experience required to do the dive as planned? Are we being over-confident expecting ourselves and each member of the team to do the dive as planned? Does that hold up if we become separated? Do I feel the same should it become necessary to rescue a buddy on this dive… can I rescue them and can they rescue me?

Self-assessment does not always return a positive answer. But self-assessment is a positive habit to fall into and it needs to become part of the pre-dive preparations for EVERY dive… especially any dive that requires the use of decompression gases to manage a decompression obligation, or that takes place in a hard overhead environment.

It’s not always deep and scary…

The same probably happens to you too. I’ll be at a dive show or some dive-related event and people will ask me about memorable dives. I think what they expect to hear are the “Boy’s Own Paper” adventure stories about a bunch of us stacked up like cordwood in a very small cave entrance to decompress; or drifting in the Gulf Stream at 60 metres being tailed by sharks and waiting for a shipwreck to appear out of the gloom. And normally, that’s what they get. However, some memorable dives are simply not framed in anything like such an exotic setting. Some dives are memorable simply because they pack an unexpected surprise… or they excite someone else… or both.

This past weekend I had the opportunity to make a dive in Lake Rosseau at the site of the long-defunct Royal Muskoka Hotel. Lake Rosseau is one of the three big lakes in Muskoka about 18 kilometers long and eight wide. The southern end of the lake is about 200 kilometers north of Toronto and for more than 150 years, along with the rest of Muskoka, has been a vacation spot and cottage country for folks from the city… and much further afield.

The Royal Muskoka Hotel was opened at the turn of the 20th century and was billed as the grandest summer resort in all of Muskoka, with room for 350 guests. Among its amenities: electric lighting, hot and cold running water, a post office, telegraph office, bar, billiard room, bakeshop, newsstand, barber shop and beauty salon. On the grounds (a little more than 50 hectares) was a golf-course, bowling greens, tennis courts, riding stables, and walking trails. It was a get-away for the rich and famous. But 50 years after it opened, in the spring of 1952, it burned to the ground, and its remains were summarily pushed into the lake.

I’d contacted a buddy who runs the marina at the modern-day equivalent of the Royal Muskoka (a J.W. Marriott resort) on the lake. I needed to complete one last skills-dive for a student doing a course with me, and a quick dip in the lake seemed like an easy way to accomplish it. He suggested going to the shore just off the site of the Royal Muskoka. There is a wall there that drops off to 45 metres and it’s close to the J.W.’s dock. Perfect. As a newly-certified diver himself, he was excited by the prospect of what my student and I might find.

I was less excited. Having dived in the local lakes on and off for more than 20 years, I knew that the visibility in most of them – especially the big three – could be hugely affected by tannic water with a similar level of transparency to a cup of strong Earl Gray tea.

Reverse of plate showing the effects of 60 years submerged

Well, I was wrong. Sure the water was the color of tea, but more like weak Darjeeling and perfectly acceptable so that, at depth, my student and I could see quite well… probably six metres or so. Certainly well enough to pick out lots of things that could have been relics from the Royal Muskoka, including a perfectly intact dessert plate: perhaps one of many laying at various points on the almost vertical wall.

My student completed her skills – timed staged decompression stops using breath cycles or drop in tank pressure and a knotted line on a DSMB rather than a depth gauge/bottom-timer: and surfacing with an unconscious diver from depth – and we celebrated her success by presenting our find — the perfectly intact plate — to our boat captain. He was ecstatic, and now wants to dive the area himself. I hope to make that happen sometime soon.

Face of plate found in Lake Rosseau

A memorable dive… because? Well, it’s cool to dive a spot that offers the chance of seeing and touching something historic, but more importantly, memorable because a new diver came away completely gob-smacked and excited about “local” diving without even getting his feet wet: although that’s not really true since the rain was coming down horizontally on the way back to the dock!


The Rules Apply to All of Us

If you are a technical diver — a cave diver, a trimix diver, a rebreather diver, something of that sort – you have read someplace that complacency kills experienced divers. Fact is, you may have read it several times and heard it said repeatedly because that phrase is contained in most if not all technical diving textbooks. It is so commonly bandied about that for some of us, it may have become a little trite… a cliché… something to become complacent about.

Time to smarten up.

Recently, there was yet another senseless death, which might serve to illustrate the point. This one happened at Ginnie Springs in north Florida.

A young guy named Carlos Fonseca had an oxygen toxicity episode a couple of hundred metres inside the cave and died. He was breathing from a stage bottle clearly marked oxygen and later analysed to be just about pure O2. According to statements from the folks diving with him, Carlos thought he was breathing air.

Before the dive started, he was questioned about the bottle, challenged about analysing it, but insisted that he had filled it with air, even though it was labeled for dedicated oxygen service. Now he is dead.

This incident is sad and terribly tragic… a family without a dad/husband/son/brother et al… But unfortunately it is not surprising that a certified cave and trimix diver died doing a simple, run of the mill dive that was WELL within the scope of his training and experience. As slight as his experience may have been, and as rapidly as he had progressed from open-water diver to cave diver, the dive was a simple one for which he had adequate training.

Diving is an activity that requires some restraint because it is so easy to push beyond one’s capabilities… as Steve Berman once said — and I paraphrase — any twerp can get to the back of a cave. But not everyone can manage the journey back out.

I did not know Carlos… never even met him… but I do know the fella who taught him to cave dive and a couple of buddies had dived with him during the past couple of years. He had progressed from open-water punter to trimix and cave in a couple of years. He had the money, time and desire to do so.

The over-arching assessment from the people I know who knew Carlos was that he was very confident… perhaps to the point of arrogance… but so what. He was certainly enthusiastic. He had completed 100 cave dives in a couple of years, and when you live a 16-20 hour drive from the caves, 100 dives is enthusiasm in bold letters. But, in truth, he really had not been diving long, and he certainly did not have vast experience regardless of his many postings on onLine forums and Facebook, and even though he had ticked off several “big” dives in his logbook. However, I do not believe any of that had anything to do with him being dead right now.

Experience whispers strange things in our ear. I have lost many, many friends to diving, and have seen many people who I did not know personally… like Carlos Fonseca… die in the water. Part of the work I choose to do involves picking through the debris folks like Carlos leave behind. The task is to identify what went wrong and make sure others understand the circumstances surrounding the incident, the events that triggered an incorrect reaction perhaps, so that nobody makes the same bloody error. Sometimes this is difficult, but not in this case. There is no doubt about what happened; no question what triggered the victim’s death or whose actions contributed to that death. Of course, the resulting analysis may be difficult for some to accept.

A buddy of mine is a lawyer who specializes in cases where some poor bastard has died, and he tells me his staff have a kind of open pool going to see how long it is before a friend or relative says, writes or posts on the internet something along the lines: “He was the best diver in the world… I simply do not understand how a thing like this could happen…”

Someone always says that, even when the diver is a total novice… just like that kid who died in California a couple of years back trying to do an air dive to 80 metres. He was a divemaster… maybe, I forget. Anyhow, he had ZERO training to do that sort of dive but the boy’s father insisted his son was a “professional” and would not accept evidence to the contrary… or that his son had probably been lulled into complacency and hubris by his slightly more experienced and certainly older dive buddies.

In the case of Carlos, we know what went wrong and we have evidence that the victim ignored warnings from his fellow divers. He certainly ignored best practice. He is not the first diver to make such a rookie mistake, and the fact that a few years ago he knew nothing at all about diving is truly irrelevant. He DID know what SHOULD have been done. He had sat through training and certainly had correctly answered exam questions on gas management. HE CHOSE TO IGNORE WHAT HE KNEW. This is not because of lack of experience or because he progressed rapidly. He simply ignored what he knew to be the right thing to do… that’s a function of character, poor judgement, pressure or stress: take your pick.

In the final assessment, Carlos Fonseca believed the rules did not apply to him. He certainly knew that the established practice is to ANALYSE and LABEL every cylinder that goes into the water.

Is there something to learn from this incident? Of course there is. It’s the title of this piece. But there is also something else I would like to remind you of just in case someone reading this has ANY doubt. YOUR BUDDY IS CARRYING YOUR CONTINGENCY GAS… IF YOU DO NOT KNOW WHAT IT IS (first-hand, having checked for yourself) THEN YOU SHOULD. YOU may need to breathe it at some point. There can be NO credible argument against this, in my opinion.

The Best Rescue Divers Don’t Have to Rescue

It may sound strange but it’s generally accepted that the best, most successful rescue divers don’t have to actually rescue anyone because they are able to recognize signs of impending panic and are savvy enough to intervene before true panic happens.

Of course, the question most aspiring rescue divers ask at this point goes something like: “Is that a learned skill, and if so, is it difficult to learn?”

The short answer is: yes it is, and no it isn’t!

When we imagine a rescue diver in action, what flashes before our eyes – initially at least – is an image of a neoprene-clad hero(ine) pulling an unconscious diver from the raging surf… Think GQ cover meets Surfer Magazine and you’re halfway there. Then after a few nanoseconds, the real image kicks in and it’s not so pretty; not as organized; and certainly not as heroic. The truth is that a full-blown rescue, as welcome as it may be in a disastrous situation, is simply something we should strive to avoid at all costs. In essence, a good rescue is one that may consists of a quiet word before the dive and either a change in the dive plan or a retreat to the nearest café for a coffee, a Danish pastry and a chat about tomorrow’s dive rather than today’s.

One of the pre-dive skills required in every technical diving program is something labelled stress assessment. This step in the pre-dive ritual is a vital “rescue” technique, and it applies to both self-assessment as well as buddy or team assessment.

Given that you and your buddy or buddies are certified, equipped and have the experience to enjoy your planned dive without undue risk, the day-by-day stock questions you should ask yourself are: Am I up for this dive? Do I feel good about the dive conditions today? Do I feel ready to do this dive? Am I comfortable with the things that need to be done to make sure this dive is fun? And finally, how does my buddy (or buddies) feel about the dive?

This step alone – coupled with honest answers and a real understanding that there is no shame in calling a dive at any time… even before you pull on your gear – goes a long way toward making you a “successful” rescue diver.

Speaking with divers following an aborted dive — a dive where things went absolutely pear-shaped — a sobering but not surprising statistic is the large percentage of them who say: “I just knew something was going to go wrong,” or “I had a funny feeling about the dive before we suited up.”

If a rescue diver has one simple but truly important task to do at the dock, on the beach, at the dive site before the actual in-water part of the dive starts, it’s to conduct a quick survey of every diver – including herself – to check if everyone really is happy with the dive plan and feels no pressure to do the dive.

During the dive itself, even without the use of diver to diver voice communications, there are ways to keep checking that everyone is happy. What are they? Let’s review the opening statement that was used to kick this article off… “Recognize signs of impending panic, and are savvy enough to intervene before it happens.”

This form of clairvoyance – being able to tell when something is about to fall off the rails and do something about it BEFORE it happens – is not telepathy or some other psychic power, but a perfectly attainable skill called Situational Awareness, and a good rescue diver needs it.

In the most general terms, situational awareness is perhaps the most under-rated, unsung components of safe and successful diving operations.

In advanced diving discussions, we have adopted the term Situational Awareness (SA) as a sort of catch-all phrase to describe what we mean when we say: “keenly aware”; and probably for good reasons. SA has been a core concept in high-stress operating environments, such as the military and aviation, for many years.

In these milieu, SA skills support the ability of individuals to handle complex and rapidly changing situations in which informed decisions – directly relating to personal and team well-being – need to be made under tight time constraints. In these high-stress settings, lack of SA is one of the primary factors in accidents attributed to Human Error.

For the purposes of rescue divers, SA is best described as being aware of what is happening around you and your team, and understanding how the flow of events, and the actions of team members will impact your dive’s goals and objectives; both now and in the near future.

It also encompasses the skill of selecting which bits of information are relevant and which are not and can be discarded.

Put briefly, SA is the chess-player’s skill but applied in an environment where checkmate can result in real physical harm, and not just a wooden game-piece being knocked sideways.

One key sign of a buddy’s comfort level while underwater is his or her respiration rate (at least on open circuit gear). A nice relaxed breathing rhythm generally means a nice relaxed diver. Faster breath cycles may be a sign of tension, carbon dioxide build-up, overwork, and are often the first outward sign that forewarns of events that can domino into bedlam if left unattended.

I have a good idea of my normal breathing rate during a moderate dive – it’s around eight per minute and therefore somewhere south of the adult resting average of 12 to 16 breaths per minute. I self-monitor during a dive, but I also pay attention to the bubble “signatures” of the divers around me, trying to pay particular attention to changes in the frequency of each diver’s exhalation. It’s certainly not a definitive marker of approaching problems, but a rapid increase in breathing is something a good rescue diver might want to pay attention to.

If your buddy starts to work hard and breath more heavily than usual, get their attention, slow them down, give them some reassurance — such as an OK sign and a squeeze on the arm — will show them that you are watching out for them. Something as simple as getting a diver to pause and wait for a few beats before carrying on can easily avert an unpleasant episode further along.

If you dive with the same crew on a pretty regular basis, you also learn other more subtle signs and body language that will indicate that they are less than comfortable.

As a rescue diver, it is always in YOUR best interest to pay attention to these little markers during a dive. Sure you may be capable of executing a perfect tired diver tow and safe ascent with a semi-conscious buddy, but why take the chance when that whole scenario can be avoided by stepping in a few minutes early?

A slightly different version of this article was first published in Technical Diving International’s eNewsletter in June 2013.

What it takes to lead a technical diving team: A suggested plan for staying real and managing risk

One of the most interesting dynamics of technical diving… both during its planning and execution… revolves around the issue of leadership. It’s not simply a question of who leads and who follows but a much more complex balancing act between responsibilities, experience, team composition and dive goals. And since technical diving is recognized as a high-risk, team-oriented activity, coming up with the correct answers can mean the difference between a great dive and a bad experience.

I guess the most important first step is to understand what we mean by leadership and the factors that inform that definition.

We should start by pointing out that one of the fundamental guidelines recommended is: “The weakest diver leads the dive.”

Now weakest in this context is not an assessment of physical strength or mental fortitude – although these may be factors in some cases. More usually a diver may be “weak” because he or she has less experience with the particular sort of dive being planned and how best to achieve the dive’s specific goals; or they may start the dive with another more subtle disadvantage. On some ocean dives, weakest may be the diver most prone to seasickness and who has taken meds to help deal with that particular stress. It may also be the diver who among his or her peers on the particular day in question wakes up the least rested or most stressed… as in “I’ll lead the dive today because I had a restless night.”

Whatever the actual reason for “weakness” the logic behind this guideline is that it helps eliminate “trust me dives.” In cases where the least experienced diver is the leader, it also offers the best opportunity for that diver to expand his or her comfort zone. Let’s take the example of a cave dive with a three-person team. For this example, let’s say that two of the team have explored the cave on several occasions but for one, this is her first time in. All three may be experienced cave divers, but one is certainly at a slight disadvantage. By having her LEAD the dive, two things are assured. Firstly, she will not be lead into a situation which she finds uncomfortable. Her level of comfort on the dive will most likely be increased since it will go at her pace, and with two companions to “guide” her when the time comes to make a decision – for example “is this the right side-passage to take…” – her comfort zone may be expanded but not breached.

The result will most likely be a much more enjoyable dive for everyone involved since stress levels can be better managed.

This example of leadership during the actual execution of a cave dive may not relate directly to the type of diving you do, but the logic is transferable to all varieties of technical or complex advanced diving whether in a hard overhead environment or not.

It also introduces us to part of the complexity that surrounds the whole question of Leadership in Technical diving, and its definition relative to the importance of coaching and mentorship in the process.

Let’s recap and redefine a little. The weakest diver leads during the EXECUTION of a dive, but this diver would most likely take a backseat role during the actual PLANNING of that same dive.

If we go back to our example, let’s travel by time-machine to a day or two before the execution of the dive to the time our three dive buddies sat down together to plan the dive. We know that all three are experienced cave dives and during their initial assessment of the dive’s parameters they agreed that each had the appropriate training, familiarity with the required equipment, and general experience in the type of environment. What was apparent was that one needed a detailed briefing on the specifics on the dive since she had never been to the site before. This is where the dynamics that influence leadership in technical diving comes into play.

In old-school terms, leadership might be interpreted as the behavior of a tartar or martinet. A person who demands strict adherence to his or her rules and any deviation from those rules will result in some sort of punitive reaction: verbal or otherwise. I am reasonably sure that many of you have first-hand experience of this form of bullying and “management” by intimidation. There is no place for this style of leadership in technical diving… or anywhere else actually. It may have worked to send hapless souls over the trenches during WWI but is about as useful in diving as ashtrays on a motorcycle. There is simply no room for this attitude anywhere close to technical divers planning their dive.

The leader during this stage needs to be empathetic, supportive and their role is more akin to a coach or mentor: someone who encourages others to contribute ideas and suggestions. A real leader shares knowledge, has real information, suggests better alternatives when asked, and gets satisfaction from helping others grow. Essentially, a good leader produces good leaders.
In the example of the planning for the cave dive, the leader might respond to questions about distances and times with something like: “what do you feel comfortable doing?” rather than pushing his or her agenda. In fact, an important part of the mentoring process is to promote the goals of others even when it makes their own subordinate.

For most of our dives, up-front considerations of leadership are a little over-the-top. The vast majority of dives – even technical ones – follow a pattern that is established within the team and roles and responsibilities are simple, understood and virtually unspoken. Often on this type of dive, leadership amounts to little more than: “Hey Jill, how about you run the reel today?” But when game-day brings those special dives… the apex dives for your team… give special consideration to the dynamics of team leadership. Oh, and remember that changing circumstances at depth, may alter who is “weakest” and may require change of “leadership!” But of course, that’s something best learned under the mentorship and coaching of an experienced technical instructor!

A slightly different version of this article appeared in TDI’s eNewsletter in May 2013


Texting back and forth with a diver who’s signed up for some training sessions with me (he’s taking a Helitrox Deco class this spring), I was explaining which elements of his program are covered by my fees. And of course in that list of items, there was no mention of the c-cards that graduates get if they pass the course (with TDI this program comprises Advanced Nitrox and Helitrox Decompression Procedures, so two c-cards).

“How much for the cards?” He asked.

“Nothing,” I wrote. “The cards are free… you earn ‘em. You can’t buy them!”

He texted back that he liked that idea. “Different to some other scuba classes I’ve taken,” he said.

This got me thinking about why, when I started to teach technical programs, I adopted the policy of “Giving Free C-Cards” to successful course graduates.

Students rarely fail the programs I offer. However, it’s not unusual for a student to have some challenges and have to do a few extra dives or work on their own for a while to grasp a concept that initially is hard to grasp… but an out-and-out fail is unusual.

Sometimes though, it happens. A student has a complete disregard for their teammates, they run out of gas repeatedly, they are simply not ready for “this type” of diving or do not have the required controls over body and mind in the water to be a technical diving. Usually, they accept my advice. Once or twice I’ve run into problems.

The one that made me very glad that I had adopted and advertized the policy that, “Your Card(s) are FREE!” took it really bad and reported me to the training department of the agency underwriting the course (which happened to be TDI).

In addition to the professional complaint, she had threatened a suit through small claims court under the assumption that her course fees included payment for c-cards. She was demanding at least that portion of the money she had paid, back. Her position was that she had paid for the course and expected to get her cards at the end of it.

Odd, don’t you think?

Anyhow, if you teach (tech or sport programs), here’s a suggestion if you do not so so already. Make it clear to your students that C-Cards are FREE, and that students earn them rather than buy them.

So, you travel with a rebreather do you?

I find myself traveling with a CCR more often than not these days, and most of the time, at least part of my journey entails airports and airport security. Surprisingly, I have few horror tales to share with you; in fact, just the opposite. I have found that with a little preparation and politeness — and leaving a few extra minutes between arriving at the terminal and my departure — things usually go very smoothly.

Let’s talk about the preparation part of the equation for a moment. Several years ago, Jill Heinerth mentioned to me that she put a note in with any rebreather kit she was carrying specifically explaining what the heck it was to security staff. I borrowed her idea.

The wording and the logos on the “letterhead” of the printed document I carry has changed a little over the years, but regardless, it always seems to work wonders. Here, for the record, is what my ‘official CCR travel document’ says.


This apparatus is a Closed-Circuit Rebreather (CCR) diver life-support system and may be safely transported as cargo, checked, or carry-on baggage. The components of this CCR system consist of a scrubber head (containing a series of gas sensors and display handset powered by an encased standard user-replaceable battery); scrubber body (containing top and bottom screens, end-caps and a feed or deflection pipe); breathing loop (containing breathing hoses, Open_circuit Bailout valve (BOV), and counter-lungs); and two scuba regulator first stages each fitted with an array of low and high-pressure hoses. Additional open-circuit scuba equipment may also be carried with this CCR life-support system.

NONE of these components offers a threat to the security and safety of inspection personnel, other passengers, carrier vessels, buildings or other property, and all components conform to NOAA (National Oceanographic and Atmospheric Administration) and WRSTC (World Recreational Scuba Training Council) recreational scuba equipment guidelines for transportation by commercial carriers.

The individual transporting this equipment should be able to show proof of certification in its use and will be willing to explain its function to any security personnel upon request.

PLEASE NOTE: Any pressure vessels (scuba cylinders) accompanying this CCR life-support system MUST be dismantled and have valves REMOVED in such a way that visual inspection of the vessel’s interior is facilitated (as per TSA/FAA ruling). Failure to conform to this stipulation voids this document.

You may find that printing this out and putting it in your baggage with your rebreather helpful.

How much of a conservative are you?

When it comes to storage and use of the ‘kitty litter’ used in rebreathers to scrub carbon dioxide from the breathing gas, I had until very recently thought of myself as ultra conservative. Turns out this was not necessarily the case.

I was careful with the storage part and careful when packing or loading the scrubber canister of any unit I dived with, but it turns out I misunderstood the actual working life of the absorbent once it was partially used.

Now I should make it clear that the only absorbent I have much experience with is Sofnolime® 797. This is a product made by Molecular Products in the UK and – in my circles at least – is the gold standard for use in closed-circuit rebreather diving. For the record, I use what’s called the non-indicating variety, which means it does not change color when suffused with Carbon Dioxide.

Sofnalime® itself looks a little like a white version of the material used in a cat box (hence its street name), and is actually a triangular cross-sectioned extruded pellet made in part from calcium hydroxide with a little sodium hydroxide mixed in, and is between 1.0 mm and 2.5 mm in size. It is alkaline (a pH between 12-14), slightly water soluble, and non-corrosive – but the dust will irritate the eyes and perhaps the skin, and inhaling it is a definite no-no.

In simplest terms possible, the chemical reaction that takes place inside a rebreather’s scrubber removes carbon dioxide and produces heat and water, and turns the soda lime into chalk (calcium carbonate). Also, for the record, in addition to proper storage and handling of unused scrubber material, used soda lime should be disposed of responsibly. Whenever possible, I take it home and then spread spent scrubber material on the garden where horticultural lime might be indicated, and put the rest in our horseshoe pit.
Ok, now with that clear, let’s focus on my misunderstanding.

Rebreather manufacturers tend to rate the working life of the scrubber material in their units based on the size of the scrubber canister. Literally on the amount of kitty litter their machine holds. In a perfect world, we might ask for a slightly more scientific method to gauge this, but referring to an X-hour scrubber is the norm. Certainly, this is what I was taught… but it is not what I teach; and here’s why.

After speaking with one of the chemists at Molecular, I learned that the method commonly used to indicate the effective life of scrubber material (i.e. Sofnalime®) is incorrect. While a freshly charged scrubber may have X or Y or N hours of potential effectiveness ahead of it, that number of hours is an estimate based on continuous use.

Let’s say for example that a rebreather manufacturer designates its scrubber duration as four hours. This means up to four hours on one dive and NOT two two-hour dives back-to-back on the same scrubber. This, according to Molecular’s chemist, would be “pushing it.” There are several other considerations that should be taken into account when estimating how much ‘life’ is left in one’s scrubber but on straight, no frills, moderate depth dives (such as shallow cave dives in North Florida which would normally be to depths less than 30 metres/100 feet) after one two-hour dive on a ‘four-hour scrubber’ perhaps only an hour and a half is left, and NOT two more hours. After a couple of one-hour dives, a third dive to 45 minutes or so, will all but exhaust the remaining Sofalime® so that in actual use, the effective life – and safest interpretation – of a four-hour scrubber would be less than three hours.

Now, it should be said that estimates of scrubber duration from manufacturers tend to be conservative and are usually based on the worst type of conditions; however, I found it interesting that the guy who oversees the manufacture and testing of the active component in the little chemistry set I lug around on my back to go diving, is more conservative yet.

And I for one will follow his example from here on in.

A word or two about underwear…

What is it about the European’s and drysuits? During the past ten years or so, I’ve owned and worn six drysuits representing five different brands. Their design and materials used are different and they’ve helped keep me warm and dry for working dives and personal dives in a lot of different locations. Well, most of them have kept me warm and dry. The only suit made in the US, was a terrible investment spending more time going backwards and forwards to the manufacturer in California for “repairs” than in the water. So let’s forget that one. The other five suits are from four manufacturers based in Germany, Poland and the UK. All five suits (two from the same company) performed and continue to perform well and remain “onLine” in the Dive Locker at home ready to do service.

Now six suits over ten years is going some! Most active divers might need two suits over a ten-year span, but in my defense… well, I don’t have a defense. Truth is that I have more suits than I need. Another truth is that for the majority of my dives over the past year, I have worn suits from one single UK-based manufacturer because they are both outstanding performers. A slight conflict of interest here. A company that I do consulting work for recently signed a deal to distribute this brand of suit in Canada and the USA. However, they did so based on the feedback of several consultants they use (including me) who had been diving the suits for a year or so. Bottom line is that we liked the suits, and our advice to our client to represent the line was based on the product’s performance rather than profit margins.

Anyhow, as you know, a drysuit is only half of the system designed to keep a diver protected from the elements. The other half are the thermal undies worn under the suit. For the record, I have more of these than I have drysuits — two-piece, one-piece, light-weight, fluffy, heavy-weight, fancy and plain. A drysuit is important. Fit, comfort, dryness and its profile in the water are critical issues, but all (in the case of shell suits) or a portion (with neoprene suits) of the actual thermal protection a diver needs to stay alert, warm and comfortable in the water comes from whatever it is the diver wears under his/her suit.

Because of this perhaps, I am even more critical and more detail oriented about the thermals I wear than the drysuit that goes over the top of them. Most of the thermals I have bought or been given over the years no longer go near the water. They are too bulky, too restrictive to allow free movement, and are a drag to dry after a day on a boat or at a cave site. These I wear to walk the dog and shovel snow in the winter. I have quite the selection, and Brad — the ex-seeing-eye German Shepard who enjoys walks in the snow and helping me move the stuff from around our house — knows that when I pull a set on during the day, it’s time to go out and play. He does not dive.

What I look for in drysuit undies is really pretty simple. I find changing conditions, and water temperature at various dive sites ranging from more than 20 degrees (C) to less than 0C (winter sea water) lend themselves to a layered approach. A good base layer will work on its own for warmer temperatures and a good extreme top layer extends the comfort zone through MOST colder water. For really cold temps, a heated vest is the best solution.

I do a lot of diving in the Great Lakes and the conditions there present an additional challenge. Summer air temperatures can be in the 30s and water temperatures at depth are a pretty constant 4 degrees C (the temperature of water at its densest). This too calls for a layered approach with the layer closest to the diver’s body capable of providing good thermal protection while wicking away the inevitable perspiration that results from putting on warm garments in summer weather.

So, I am on a constant lookout for thermals that suit those varied needs. It also helps if they pack small, dry rapidly, and are made well enough to last more than a few dives before seams let go or become unravelled.

A month or so ago, I was in the UK doing a factory inspection of the O’Three facility in Dorset. The company’s drysuits are spectacular. The owners of the company have been pushing their undergarments to me for a while, and during my trip to see them in the UK, I was convinced to give their Point Below Base (PBB) system a trial at the first opportunity.

That opportunity was earlier this month, cave diving in Marianna in Florida’s pan handle. Conditions were perfect for this type of trial… Water temperatures ranging from 17 to 20 C and air temperatures all over the map from about 25 as a high and minus 3 at the start of the day on a few occasions.

The O’Three PBB+ Thermals performed very well and I am impressed. They were actually warmer than a much bulkier 200 gram one-piece suit with light wicking undies underneath. After two-hours in the water, I was as warm as toast and multiple dives were not a problem.

The PBB+ is a two-piece system consisting of a farmer john-style pants and bib with a pullover top to protect the arms and to give a little more insulation to the core.

You can read a much more detailed account of the technology, features and benefits on O’Three’s website:

But the Cole’s Notes version is simply this: I like the design, the materials, the insulation factor*, and PBB+’s ability to wick away moisture and dry quickly when it does get wet. Frankly, if you’re anything like me and always on the look out for something to keep you warm on those long dives, this may be the answer.

A little plug: O’Three products including PBB undies are priced competitively here in North America and available from Silent Diving LLC… or me. </commercial break>

*As an aside, I do not know how relevant readings for garment insulation based on Clo or Tog units are to describe the performance of drysuit underwear… and in any event, I have no idea if anyone at O’Three has bothered to rate their PBB+ thermals, but I also own a one-piece thermal suit from a rival manufacturer that is rated to 1.45 Clo, and the PBB+ system was warmer, and way more comfortable, and less bulky. Viva new materials… Viva new technology!

Questions to ask – and answers to expect – when you research which CCR is right for you…

Let’s take as given that your research so far has turned up that the type of diver you are, and the type of diving you like to do – now or in the near future – makes you a good candidate to invest in a closed-circuit rebreather.


So far, so good, but now you need to pick which type of rebreather is going to be the best investment. You can find plenty of help on that score… almost every CCR diver thinks his or her unit is the best around, and in a way, that can hardly be surprising since they’ve invested a lot of money and time into it. And admitting you made a mistake of that magnitude is tough for anyone to admit to.


The decision-making process WILL be easier for you if you can log a few hours on various units BEFORE making any final commitment. And the rather worn out advice that it is not the agency that counts but the instructor is actually very true with CCR training, so picking the instructor can be as important as picking a unit.


But all that said and done, there are some fundamental questions that you should be armed with before you hand over the admission fees to diving without bubbles. The list below contains a few that I think are important. Look them over. I hope they help. Let me know what you think.


Is the CCR you are considering CE approved? It should be because CE approval connotes rigorous third-party testing for important performance issues such as work of breathing and overall functionality.


What is the tested depth rating? Some manufacturers put a depth limit on their gear and diving deeper than the depth recommended in the user manual is simply a poor judgment call.


Does the CCR you’re looking at have Over the Shoulder (Front) or Rear Mounted Counterlung design? There really isn’t a great deal of difference between the two, but there are advantages to each. As far as I know, only one manufacturer offers divers the choice with BOTH options with both carrying CE Certification.


What type of Oxygen Injection System, is used in the CCR you are looking at? Options include a Constant Flow Orifice, diver adjustable Variable Flow Orifice, a Static Solenoid or a Dynamic Solenoid. If you are looking for a CCR with the option of automatic set-point control, look for one with a Dynamic Solenoid capable of delivering continuous and instant reaction to changes in oxygen partial pressure in the diving loop.


If the unit uses oxygen controllers (has an automatic option) does it have independent dual controllers? It should do otherwise there is no backup in a system that is vital to life support.


How well will it maintain constant PO2 during ascent? This really comes back to controllers. During ascent the partial pressure of oxygen in the diver’s breathing loop can drop dramatically and even to hypoxic levels as the ambient pressure drops. Unless the CCR’s oxygen controller has the ability to react correctly and rapidly to these changes, the diver is at serious risk and the unit is poorly designed.


Does it have a CO2 Scrubber performance monitor? The scrubber bed is where carbon dioxide is removed from exhaled breath. There are several factors that can have a negative effect on its performance and how effectively it does its job. Since the chemical reaction that takes place in the scrubber material generates heat, a smart way to monitor performance is to measure which portion of the bed is “hot” and display that to the diver.


Does it have a CO2 Sensor? By following a few basic “rules” and sticking to certain guidelines, CO2 breakthrough can be avoided, but many divers feel more comfortable and secure with this type of sensor in place. If you’d like one, is it available on the CCR you’re considering?


Does it have Heads Up Display (HUD) and what information does it show to the diver? An HUD is a useful tool, but some are confusing and seem less than intuitive. An HUD should convey exactly the information necessary for the diver to fly the unit safely, and this includes warning when PO2 is outside set parameters, when battery power drops, and when the scrubber bed is reaching the end of its effective life.


Does it have real-time Nitrox / Trimix Computer designed and manufactured by the same people who built the CCR? It should. Some CCRs use controllers and computers from third-party suppliers. This may suit some risk models and business plans, but this approach is outside my personal comfort level. Of course yours may vary, but I like these two “bits” of my CCR to be integrated. I also think it helps when the Quality Assurance that keeps me safe on the rebreather extends to the computer feeding me information about CCR function and my decompression status.


Does the CCR you’re looking at have Automatic Depth Setpoint switching, and can that auto function be overridden simply without lots of button pushing? This is a good feature that can help to manage the risks of decompression stress, among other issues.


Does it have audible and visual alarms for crucial issues such as low or high PO2, high CO2, and scrubber life? These items are critically important. I try to dive my unit so that no alarms are triggered, but it’s nice to know there’s a back-up.


Are parts and service availability worldwide? If you travel, it would be nice to know that in the event of something breaking, a replacement part is not sitting in a warehouse someplace on the other side of the world and a several days away from access to world-wide shipping.


How much service is required? Good industrial design and well made parts put together in an ISO 9001 factory rather than outsourced to the cheapest off-shore knock-off house cannot come close to a 100 percent guarantee that things will work as expected, but they help us to come close.


Is there a backup power source? If a machine uses battery power to function, then there should be an independent backup battery pack and a mechanism to switch seamlessly from one to the other should it be required.


Can it be upgraded for Technical Trimix Diving? Not all CCR divers are interested in technical diving, but if you one day decide to take up technical diving, ask yourself if will you have to sell your unit and start again with a new model.


Does it have PC Interface and Dive log download? This is a nice feature to have at any time, but it becomes amazing when you can send that log to the manufacturer for system diagnostics.

“What could possibly go wrong?”

For a quick and dirty definition, you might say that planning for a technical dive is mostly about working out how to deal with contingencies when something hits the fan.

Of course that definition does beg a few questions: for example, exactly which contingencies does one have to deal with during a technical dive, and how fast is the fan likely to be spinning? But as a starting point, and in particular when trying to explain what the sport is all about to someone who is neither trained in nor familiar with technical diving, it works as well as anything else.

One of the first instructor-trainers I worked with was extremely fond of charts and graphs. His students left his workshops and classes with the impression that he had pie charts, bar graphs and spread-sheets of stats for almost everything related to diving. He could tell you what percentage of aluminum 80 cylinders made in a particular year by one or two manufacturers were painted red; or the total number of snorkel keepers that sat unused in the bottom of save-a-dive kits world-wide; or how many open-water divers out of a graduating class of, say, 100 would go on to become dive masters. Totally worthless information in most instances, but what it lacked in usefulness was compensated for in a perverse way by him having lots and lots of it.

Naturally and in accordance with the laws of nature, hidden away among the chaff were a few kernels of useful data too. For example, he had a chart showing the average number of catastrophic gas emergencies year by year per 1,000 dives by certified cave divers.

Much to my disappointment, I am unable to remember any of those figures – useful or otherwise – and in any event I was reasonably sure at the time of first hearing that a good percentage of his data were suspect and most probably thrown together the evening before he was due to share them with us – his eager new instructor candidates. I believe a good number of them were creative artifacts crafted in-situ, so to speak, to add an atmosphere of scientific sincerity to his otherwise wildly entertaining, right-brain presentations.

However, what I can remember was a favorite phrase he used when outlining for us what was involved in his version of contingency planning – “covering your arse” – whether diving on our own, with buddies or with students.

“You can, without much real effort,” he would say. “Contingency yourself right out of the water, and quickly arrive at a point where any and every dive looks too risky to undertake…”

During one presentation, he said: “Let’s take as a given that poor safety engineering in life-critical systems such as low-cost scuba regulators is reasonably commonplace.” He explained that based on the average diver’s yen to save a buck on kit, you could easily create a hugely pessimistic risk assessment for that average diver: especially if you wanted to factor in bad habits like not doing proper pre-dive checks.

Following that logic, and considering the magnitude of loss associated with diving accidents (the threats of death by drowning, embolism, oxygen toxicity, severe decompression sickness, et al) any argument that the probability of said failure is unlikely was smothered.

“Quantitative arguments about kit being unlikely to give up the ghost and go pear-shaped,” he told us; “Are moot if we were to agree that the common human reaction to component failure is panic: and since we cannot reduce instances of component gear failure to zero, and panic usually results in death or injury, diving is unsafe and should never be attempted.

“Clearly this is, to a great extent, bullshit,” he said, “Otherwise we would have to wade through a slurry of dead people at every dive site we visit. But it’s worth noting that people die sometimes for no better reason than they were surprised and unprepared.” He wrapped up the lecture by explaining that the secret is to know what has the shortest odds of actually going wrong on a dive and focusing one’s primary efforts on that, but also being prepared for the unexpected.

A rational and reasonably careful look at the situation makes it obvious that all the threats presented by diving can never be eliminated. So if we want to dive, we have to learn to be happy with an action-plan that deals primarily with threats that are real and that might actually happen. And when we have that sorted out, and before venturing deeper and longer than a sport dive, we should include cover your arse strategies for the unusual… because Murphy is a devious bastard.

I should admit that I am lazy. If there is an easier way to be effective, I’ll find it; and if it’s possible to reuse something again and again until it’s frayed and worn thin, I do so without much hesitation. There are some provisos but those are my guidelines… especially for contingency dive plans.

I am a huge fan of using and reusing the Apex Dive concept. The definition of apex dive that I use and teach is that we can separate various dives into categories by considering the equipment and training required to do the dive. To some extent, the depth and gear limits outlined in most of the technical dive programs I teach, help to draw hard lines around the otherwise ill-defined concept of a “Technical Dive.”

For example, one category of apex dive is for an open-circuit staged decompression dive in open water from a “starting” depth of 30 metres (100 feet) to a maximum depth of about 45 metres (that’s around 150 feet to my non-metric American and Canadian friends). If we add to this the limits we accept is we will use one decompression gas and work within the gas volume rules for only two cylinders of bottom-mix, we have defined the apex dive for graduate from a TDI Helitrox Decompression Program.

I have written down and available in my kit a “simple” action plan for this level of dive, and it includes set waypoints, maximum duration (given a specific minimum starting gas volume), ascent schedules, bailout schedule, lost gas plans, bailout scenarios, what to do if various pieces of kit fail, how to and how long to conduct a search for a lost buddy, how to bring an injured or unconscious buddy to the surface, and so on and so forth.

This apex dive plan is designed to be used with ANY O/C dive at this level or shallower and shorter. I use a similar approach to other categories of dives to greater depths (60, 75, 85 metres for example), and shallower (to depths of only 30 metres specifically), and for dives in different environments such as caves. I also have a similar array of plans for similar dives on a closed-circuit rebreather.

Much of a plan laid out at one level, is almost exactly the same as the plans for dives at the level below or above. The gas management plans, ascent and bailout schedules change of course, but a lot of the scaffold keeping the plan upright, is common across the board. Also for each of these dive plans there is a segment you could call the “it’s been a really bad day” scenario. The situations covered in this are the ones that are unlikely to occur, but which carry with them, a really serious magnitude of loss.

Some of these situations are the “contingency yourself out of the water” scenarios that my old IT told his classes about. Notwithstanding his advice to “ignore the unlikely,” it seems prudent to me to have something in place to deal with several of the unlikely possibilities when diving deep and long.

For example, I have nothing that will help me deal with a lightning strike while hanging on a decompression line, but I do have a plan to help get me back to the surface with a broken buoyancy device. As unlikely as it is that a wing would spring a catastrophic leak underwater, most wings used in technical diving do have a ludicrously venerable weak point: the 15-cent plastic elbow that connects its inflation hose to the body of the wing itself.

While judicious handling during transportation, a good assembly and pre-dive inspection, and a bubble-check before descending can all help prevent this particular failure, losing a wing at depth would be serious, and in most cases could really ruin your day.

At some point in the past, you have probably heard the advice to dive a balanced rig. A balanced rig is, according to a definition just read on Wikipedia and a couple of diving websites, a rig that a diver can swim to the surface from depth without the help of a wing/buoyancy device when the cylinders are empty because it will then be “neutrally buoyant.” Someone with a rudimentary understanding of dive kit and basic physics might read the previous sentence and tell themselves: “yea, sounds legit.” The rest of us may be left with some nagging doubts.

For example, what’s with that “neutral with empty cylinders” nonsense? I am a fan of divers NOT getting into the water with too much ballast but cylinders are never empty and since whatever gas is in them has mass, surely in a balanced rig/broken wing scenario, gravity is going to win.

In my opinion, we need some alternative to swimming our kit and ourselves up from depth without ANY assistance. As luck would have it, we do not have to look far for some solutions.

Unlike most sport divers, few open-circuit technical divers have truly ditchable weights. Their ballast is supplied by integral items of kit such as steel primary cylinders and a stainless-steel backplate. Sidemount divers may have the option of dropping one primary cylinder if needed, but divers wearing back-mounted doubles do not. Therefore, in the event of a wing failure – however unlikely – a good plan is to have some back-up buoyancy or a structure plan that includes some potentially helpful suggestions.

Here are a couple of tactics that may help you if the inflation hose and your wing become separate entities while you are faced with a long ascent between you and a cup of hot chocolate back on the surface.

My council would be to forget trying the “swim up balanced kit” technique. By all means work on the principal of wearing a “balanced kit,” but understand that a long staged-decompression ascent is not something you want to undertake as a continuous swim.

If there is structure nearby – a wall, shelf, wreck whatever — use it to stabilize yourself. Grab it, get yourself sorted out, “talk” the situation through with your buddy and try to relax. Unless your wing failure was accompanied by a huge loss of gas from your cylinder, you have something to breathe while you think. Relax and work out your options. If there is no structure, grab your buddy and use them as a stabilizer. It’s surprisingly simple to hang onto a buddy’s harness and let them add a little additional gas to their wing to support the two of you. But it does require a little practice!

Let’s assume you are wearing a drysuit. Add a little gas to it to offset gravity a little. You may be lucky and your suit may be all the help you need. Keep your buddy or buddies close, and start your ascent. Good luck and let’s meet up for a coffee sometime… but chances are that your suit may not overcome gravity’s pull completely.

If there is an upline, make for it and use it. At this point it may be worth noting that a prussic loop can be useful place to hang from while you work on options. A prussic is simple to tie to an upline and can be used just as effectively as an ascender is used in rock climbing (their original application). I carry a length of 3mm equipment line tied in a long loop in my wetnotes for this reason.

Things should be golden with the combination of a solid upline, a drysuit and a prussic loop, plus the administrations of your buddy to help with stage deployment etc. as needed. But what if there is no upline.

This would be a good time to send a DSMB aloft. Actually, it may be prudent to deploy a DSMB even if there is an upline, depending on how your surface support has been briefed. With the exception of the very smallest, silliest “safety sausage,” a DSMB (a Delayed Surface Marker Buoy) should provide sufficient lift to support a diver in place of a wing. If you have the choice, you may prefer to hang from a line attached to a small cave or wreck reel rather than a spool in this situation, but either works just fine… and spools rarely jam or bird’s nest.

In several thousand dives, I have had one wing failure and one buddy have a complete failure. I have conducted a couple of test dives with the dump valve removed from my wing – just for the fun of it – but only one real-world failure. Therefore, the weight of logic and statistical evidence is on their side of the argument that states that this type of gear failure is highly unlikely. It really is, and chances are it will never happen to you at any time. However, next time you have a dive planned with your usual buddies at a site with a hard bottom within sensible distance of the surface, and you have nothing better to do, try this. Empty your wing completely and get yourself back to the surface using an alternative method. You will certainly learn something about yourself and possibly your buddy, and most likely you’ll have fun too.

Remember as well, it does not take much to contingency yourself out of the water, but with a little forward thinking, planning and practice, there is no need to.

Inspection of a CCR after an accident…

One of the findings at Rebreather Forum 3.0 was for CCR manufacturers and other community members to publish a worksheet to help accident investigators collect meaningful data from rebreathers involved in diver deaths. A sombre topic for sure but the need to have some “standards” and some sort of unit-specific checklists is apparent given the wide gaps in information gathering to date.

Martin Parker — the managing director of Ambient Pressure Diving, the manufacturer of Vision Rebreathers (the Inspiration, Evolution and Evolution+) — recently posted a worksheet. It is available in PDF form from the link below.

Click Here

The description of some procedures are graphic and not suitable reading perhaps for the squeamish; however, I believe this is a good start… Kudos to Martin.


Hi: and congratulations on your new open-water certification. Diving is extremely cool and I hope you get as much out of the experience as you can: talk about opportunities… wow!

You probably do not recall everything you read while doing the academic work to earn your certification, so I would like to take this chance to remind you of something important: An overhead is no place for an open-water diver: period. There should be no exceptions to this.

I’m writing to tell you this because there is a chance that sometime soon, someone – perhaps a buddy or a more experienced diver, maybe even an instructor – will try to tell you differently. Please tell them they are wrong. You can quote me if you like, and you can use stronger language too, but much more importantly, you can find the same advice in training manuals from EVERY agency and any reputable dive professional. Please take the time to check this out.

Caves, caverns, and the inside of wrecks, are NOT places to find yourself without specialized training. And I do not mean advanced open-water, or rescue diver or even a divemaster or instructor training but specialized training in those specific environments. If the person, even an instructor, trying to get you into a cavern or cave, calls you a wimp or says that everything will be OK as long as you “stay close and follow me,” please walk away. It could save your life and in any event, will send the right message.

If they are an instructor, suggest they reread their standards and procedures manual – it really does not matter which agency they teach for because they ALL forbid this sort of behavior and this type of dive. Fact is, suggesting that you let them “guide” you into an overhead environment could get them reprimanded and their teaching status suspended.

A few days ago, a buddy of mine pulled an open water diver out of a cave in North Florida. Against all odds in this sort of scenario, she was alive… shaken, but alive.

Her explanation was that she went into the cave just to take a quick peek at what was in there because someone (her Dad) had convinced her that as long as she did not go in too far, she’d be fine.

In a perfect and just world, she will be able to sit down sometime soon with her idiot father to have a chat. She almost died. She would have died if my friend had not been there to find and save her. (He is, by the way, a very experienced cave instructor and explorer.)

OK, so here are some things to think about. Untrained divers kill themselves in caves with sad regularity. This has been happening for years and unfortunately continues to happen even though it is preventable. People who should know better and who have read the “rules” choose to ignore common sense and believe they are immune from the laws of physics… and Murphy.

The poor sap who ends up dead may have been told that caverns and caves are safe, and believed it. They may also have been a super master specialty open-water instructor and have a collection of badges as long as their arm, but all that means bugger-all inside a cave when they realize they are lost, are sucking seeds and stems from their almost depleted single cylinder, and start to claw at the limestone ceiling and walls wailing for salvation.

Caves can be beautiful but that beauty can become extremely ugly in a couple of heartbeats. Here are some things that have happened to untrained divers who almost died in a cavern or cave but somehow managed to find their way out.

“We only intended to swim in a little way, but there were lots of passages and we got turned around…”
“The water was really clear but my buddy crashed into the bottom and I lost sight of him and the exit. I think he is still in there…”
“We had a light between us but it went out. It was really dark and I kept swimming into the walls…
“I swum in a little way and then my octo started to freeflow…”
“We followed a line and it just stopped and then I got tangled in it…”
“I panicked when I turned and could not see the exit.”

There are no grey areas when it comes to this overhead stuff. Going in there without the right kit and training is seriously tempting fate, and there are so many other ways to enjoy yourself with scuba. Please, please, do not go into an overhead until you get training in overhead diving and get yourself some serious kit and gain the experience to use it properly.

Thanks. Now go dive… in open water.

Steve Lewis
TDI instructor trainer #6

Air Breaks… what are they, and do people take them for the wrong reason?

I find the concept of taking air breaks to manage oxygen toxicity while decompressing comparable to using a paper towel to mop up an incoming tide at the beach. Or put another way, air breaks in this context are about as useful as ashtrays on a motorcycle.

Allow me to explain. I believe oxygen toxicity is one of the biggest risks to recreational divers, especially technical divers, but air-breaks as commonly described and executed, are no substitute for proper CNS planning… and are useless as a CNS management tool in any event.

The first time I remember hearing the term air-breaks was in a conversation with a hyperbaric doctor over a bottle of wine and a grilled fish supper some years back. The context was a discussion about the practice of getting hyperbaric chamber patients on air after 20-minute spells breathing pure oxygen at a “dry depth” of 18 metres (60 feet). Of course, this therapy – part of the procedures called for in the US Navy Diving Manual – delivers an oxygen partial pressure of 2.8 bar, well in excess of the 1.6 bar recommended as a maximum for recreational divers… technical or otherwise. I have no clue how or who decided that this term was the right one to use to describe the practice of switching to a low-oxygen content gas after breathing oxygen during staged decompression stops in the water. Nor can I fathom what it can possibly have to do with managing central nervous system (or pulmonary toxicity, gods forbid) while recreational diving.

Oxygen toxicity is a condition resulting from the harmful effects of breathing oxygen at elevated partial pressures. The most serious form of oxygen toxicity has the potential to affect a diver’s central nervous system and is a result of breathing very high-partial pressures (more than one bar or atmosphere) for a relatively short period of time (less than a few minutes at extreme levels). This type of toxicity may result in a clonic-tonic seizure; which in the water usually means death by embolism or drowning. Historically, this central nervous system condition was called the Paul Bert effect. The less problematic whole-body or pulmonary condition – a function of breathing lower partial pressures (less than one bar) over much longer periods – goes under the name the Lorrain Smith Effect, after the researchers who pioneered its discovery and description in the late 19th century.

I have heard and read that divers manage both Paul Bert and even Lorrain Smith effects by taking a short “air-break” during moderately long decompressions. The typical scenario is this: A diver conducts a deep or deepish dive which earns her a lengthy series of staged decompression stops on her way back to the surface. She finishes her dive by breathing pure oxygen at 6 metres on up. In this scenario, the decompression schedule requires the diver to breathe oxygen for around 20 minutes. There are a pile of variations on this theme, but the common thread is a fair amount of time breathing a gas that is delivering around 1.6 bar of oxygen… by the way, the NOAA limit for exposure to 1.6 bar of oxygen for a diver is 45 minutes, so this type of exposure does load a diver with the potential for a CNS incident… there is no argument there.

The “air-break” myth goes something like this. At some point during her spell breathing pure oxygen – sometimes at the end and sometime mid-stream – the diver will “RESET” her CNS “clock” by switching from breathing oxygen to breathing bottom mix, air, a less oxygen-rich nitrox (typically the mix she was breathing during her ascent to her final stops). Let’s illustrate the air-break protocol with a dive profile calling for a final decompression stop for 21 minutes at six metres or 20 feet. In this example, the diver might use oxygen for ten minutes, and then switch to say an EAN50 for five minutes, and finally switch back to oxygen for eleven minutes to finish up their deco. Typically, as in this example, the time spent on an “air-break” is not credited against the decompression obligation.

What I have yet to hear fully explained is how a five-minute break from breathing pure O2 resets a diver’s CNS loading during this procedure. Actually, you may also read postings from divers who rely on the same technique to manage Lorrain Smith effect, which shows an even greater misinterpretation of the mechanism behind the syndrome*.

OK, let’s take a step back and turn on the logic filter. According to NOAA – the folks who literally set the standards for nitrox use in the recreational dive community – a period of 20 minutes breathing oxygen at 6 metres – a practice that delivers a partial pressure or oxygen depth of around 1.6 bar/ata – has a corresponding time limit of 45 minutes. When we calculate the CNS loading for a dive, we are taught to account for the CNS loading for ALL phases of the dive. That’s to say, every minute spent breathing elevated levels of oxygen. Let’s ignore whatever came before during our example dive, and let us just focus on what happens at six metres or 20 feet. In a nutshell: The diver has to account for 20 minutes on pure oxygen. The NOAA tables don’t give a rat’s behind whether those 20 minutes are accumulated in one lump or two… or three or four. Twenty minutes is 20 minutes and uses up about 44-45 percent of the total allowable time regardless! The five minutes breathing another gas – in our example we can say she used EAN50 delivering an oxygen partial pressure of about 0.8 bar – simply adds a little to the total CNS loading, albeit a very tiny about (less than one percent). There is nothing in the NOAA dive manual or any of Hamilton’s published work that tells us anything different.

Now, to set the record straight, faced with the situation outlined above and breathing pure oxygen for that long, the chances are that I would take an air-break and recommend taking one to my team-mates; however, it has NOTHING to do with CNS but rather to help optimize off-gassing.

Oxygen is a vasoconstrictor – it causes some blood vessels to shut or partially shut – which may have some effect on general perfusion levels. This does not seem like a great plan for those of us trying to eliminate dissolved inert gas.
The bottom line is this: Let’s agree to take a break from pure O2 during our deco, but let’s not confuse the issue by suggesting that doing so magically helps manage CNS toxicity. Better yet, let’s opt to employ a better option and a slightly more helpful gas. But more about that later.

* Prolonged breathing of gas with an Fio2 (Fractional Inspired Oxygen) greater than 60 kPa (0.6 bar/ata)can lead to pulmonary toxicity and eventually irreversible pulmonary fibrosis, but this takes many hours or days and does not constitute an issue for the rank and file technical diver. Most likely, the “burning” sensation and pulmonary toxicity like symptoms mentioned by technical divers breathing oxygen and oxygen-rich gas during recreational decompression is a function of breathing cold, dry air (the dew-point of oxygen in the cylinders in my fill station is marked as -40! That’s dry.) This air has the ability to dry the mucus membranes lining our lungs and bringing on something called dry-air asthma. A less far-fetched probable outcome than pulmonary toxicity.

Bounce Dives… what to do if you find yourself doing one

According to the divers I know and respect, decompression theory is more fiction than fact, less science than art. They seem to agree that there for every constant we have to account for when we dive, there are about ten times more variables in play, and so the management of decompression stress – a nice euphemism for the best ways to avoid getting bent – is mostly a blend of luck and weighted dice.

Over the course of several thousand dives, a large percentage of them requiring staged decompression, I have been extraordinary lucky and have never ended a dive with a trip to a re-compression chamber.

There may be several factors at play in my case and any one of them may have helped me avoid getting bent… or more correctly, chamber bent. Genetics, running conservative dive schedules, making generous use of heliox, nitrox or oxygen during my ascents (sometimes all three), and having a medical condition that requires me to be pretty well hydrated all the time… at least better hydrated than the average North American male. However, one thing that I feel has helped is that I have avoided short-duration dives (bounce dives) after a deep staged dive like the plague. And on the few occasions a scheduled second dive ended up much shorter than planned – mostly because of a bailout situation following something hitting the proverbial spinning fan – I’ve followed the tactic of pulling a long ascent schedule followed by a long surface interval (four hours or more) before getting back in the water to conduct another dive.

During a conversation about decompression strategies with John Crea – an anesthesiologist and an early member of the technical diving community – he mentioned that the outcome of bounce dives – specifically the behavior of absorbed gas in a diver’s body – is notoriously unpredictable. Crea and Bill Hamilton once told the audience at a technical diving conference that decompression is a crap shoot. During that conversation, he said that bounce dives elevate the crap shoot up to a game of Russian roulette. I have no reason to question his logic.

Here’s part of the issue. For most people, the bulk of off-gassing is likely to take place when a diver is back on the surface and at one bar or one atmosphere. Doppler ultrasound scans tell us that after a few minutes out of the water, it’s party-time for inert gas bubbles with levels of free-phase gas at their highest relative to what happened in the water during ascent. These bubbles continue to grow in number and size as time passes, with the peak – especially following a deep dive – not being reached until one or two hours into the SIT.

This is nothing new to those who regularly conduct staged deco dives, but the key here is to understand what happens when most divers follow up a decompression dive with a second “shorter” dive… say to retrieve a hook or a piece of kit left on the bottom. Essentially that second dive is comparable to opening up a shunt between the venous side of one’s bloodstream to the arterial. Diving MAY compress bubbles sufficiently to bypass the lungs and re-circulate them. A bounce dive profile can easily allow these bubbles to then expand during ascent and cause all sorts of complications… including bringing on the bends.

Naturally, bounce dives are easy to avoid… in most cases. For example, I would hope most divers understand that dropping a stage bottle in 6-10 metres (20-30 feet) of water after a deco dive and jumping in to fish it out, is EXACTLY the thing to avoid. However, here’s another scenario that I was reminded of last week while diving a trimix-depth wreck in Lake Ontario.

The wreck has no permanent buoy and so our dive boat made a pass and dropped a small mushroom anchor with a length of line with a small tuna ball tied to the end. The first team dropped in but the line had been fouled and did not deploy correctly. When they arrived at 45 metres (about 150 feet), there was no sign of the two-masted schooner we’d come to dive – only mud. They did a short search and opted to run a bailout profile that called for a few minutes of hang-time.  According to all that’s outlined above, they decided their day was shot and they did not bother to try another dive with a short surface interval between, which is what would have been called for given the day’s schedule. Their actions were conservative, but in my opinion, justified and correct given the circumstances.

By definition, a second dive would have been shorter than the first since their available gas volume would have been limited. Admittedly, the second dive would not have been a shallow bounce – probably it would have been almost as deep as their aborted dive – and it would have required a short staged ascent – perhaps similar to their bailout profile – but they figured the odds of bubble trouble would be greatly increased by getting back in the water to try again.

Were their actions correct? Could we really have classified their second dive a bounce? Good questions, but think about this possible scenario.

Given all we think we know about off-gassing and the state of the bubbling following their first dive, what might have happened if they had opted to try that second dive, and when they got to 9 metres or 30 feet, they saw that the down-line was fouled again? Might they have aborted the dive and surfaced? That would have been a bounce now wouldn’t it?

In effect, there are several possible situations that would have the potential to make their second dive a bounce dive, including having to bailout again because of the anchor missing its mark or one of their three-person team thumbing the dive during its early stages. I would suggest that the specific situation they found themselves in after their first dive is one that many technical wreck divers may be faced with when diving sites that are not part of the regular “tourist” fare. I think their choice to hang up the fins for the day, was the right one.  But then, I think we already established that when it comes to decompression theory, I am conservative. That’s fine by me. How about you?

The Five-Minute Neurological Exam: don’t leave home without it!

I was somewhat surprised to learn that although the majority of technical divers believe in the value of the simple neurological exam — taught to students during decompression courses to identify signs of potential DCS — few carry a printed copy (or pdf on their phone or tablet) with them on their dives.

What follows is ONE of several versions that exist.  I use it because it seems the most comprehensive and straightforward. Regardless of if you opt to use this or another, remember to record the results, and in particular to note any abnormalities. If a dive buddy is evacuated for evaluation at a hyperbaric facility or even a hospital emergency department, sending a notarized copy of this with them may help them get treated more rapidly.

There are NINE test categories… #  1, 7 and 9 are key.

1. Orientation (these may sound facile but they may indicate real confusion in a otherwise normal-looking victim… do not omit them).

  • Ask diver for full name and age
  • Ask diver to state present location
  • Ask diver what time it is, what day of the week, the date and month

2. Eyes / Vision

  • Ask diver to count the number of fingers you display (do this several times using different numbers)
  • Check eyes together and then separately
  • Ask the diver to describe a distant object… something several metres (yards) away at least
  • Have diver follow your clenched fist with his/her eyes as you move it up, down, left and right in front of their face. Have them hold their head still and check that their eyes follow your movements smoothly
  • Check both pupils are equal in size

3. Face (muscles and nerves)

  • Ask the diver to smile and check there is symmetry in their expression
  • Have the diver whistle. Watch the “pucker”. Note any drooping of lips.
  • Have the diver close their mouth tightly and feel that their jaw muscles are equally tight
  • With their eyes closed, stroke the diver’s face, forehead and neck and ask them to describe the sensation. It should be similar

4. Hearing

  • Check hearing by rubbing your thumb and forefinger together with the diver’s eyes closed. See how close the fingers have to be to be audible.

Note: If the surroundings are noisy, ask bystanders to be quiet and have noisy machinery turned off if possible.

5. Swallowing Reflex

  • Have the diver take a sip of water and watch their “Adam’s apple” as they swallow to be sure it moves up and down

6. Tongue

  • Have the diver stick out their tongue. Note if it droops, moves to one side or other abnormal movements.

7. Muscle Strength

  • Place your hands firmly on the diver’s shoulders, have them “shrug”. Note if there is any difference in strength
  • Have the diver squeeze your fingers with both hands at the same time, notice any difference in strength. Have the diver hold his hands together at chest level and elbows high. Gently push and pull the elbows while the diver resists the movement. Notice any difference in strength
  • Check leg strength by having the diver lie flat and raise and lower the legs while you resist the movement

8. Sensory Perception

  • Check the diver’s ability to feel you touching them lightly starting at their shoulders and working down to cover their entire body. Compare degree of response on each side. The diver’s eyes should be closed while this is done.

9. Balance and Coordination

Note: Be prepared to protect the diver from injury when performing this test.

  • If possible, have the diver walk heel to toe and check balance and coordination. Make sure the diver does not fall!
  • Have the diver stand with feet together and eyes closed. Ask them to hold their arms straight out, and hold that position for half a minute at least. Be ready to catch them if they lose their balance or fall.

After the exam…

The diver’s condition or the environment may prevent you conducting one or more of these tests. Record any omitted test and the reason.

A cycle of tests should be repeated at 30- to 60-minute intervals while awaiting assistance in order to determine if any change occurs. Report the results to the emergency medical personnel responding to the call.

If there is a delay getting to a suitable recompression facility, repeat the test hourly.

Technology and Technical Diving… these are not your granny’s computers

(A very similar version of this article was first published in issue 24 of Underwater Journal, an underwater adventure magazine)

With the rising popularity of sidemount diving, semi-closed and fully closed-circuit rebreathers, and of course the ubiquitous popularity of traditional North Florida Cave diver’s kit (doubles, manifold, backplate and wing), it sometimes easy to forget that the majority of divers still manage to have plenty of fun underwater wearing a single cylinder!  A single cylinder is simple, comparatively light-weight, easy to set-up and operate, and is without doubt the most common kit configuration among scuba divers around the globe. But as popular as it is, a single cylinder does have one huge drawback, and a growing number of recreational sport divers recognize the short-coming and have opted to do something about it.

Chances are good that if you are a graduate from an SDI Solo Diver program, or if you came up through the University of Hard-Knocks, you probably already know that one huge drawback is that the diver has very limited options when Murphy tags along as a dive buddy. For example, with only one regulator first stage, the only backup life-support system is your buddy’s octo. A massive free-flow really gives little alternative but to share air and get outta Dodge.

Options are even more limited if your buddy is way over there not paying attention to anything but the critter in his viewfinder. A free-flowing regulator can empty a freshly filled cylinder in minutes, and the deeper you go, the faster it drains. Swopping regs and heading to the surface maybe the only course of action open to you. Unless you count reaching BEHIND your head and feathering the valve on your single tank; and turning off your air to fix a free-flow is definitely not something you’d want to try as an emergency as hoc drill anyway. Truth is that without pool practice and at very least a donated octopus (backup reg) attached to your buddy’s tank in your mouth, a sport diver should never turn off his gas.

The simple alternative is to carry a redundant gas source and the most functional and practical for the average single-tank diver is a “pony bottle.”

Time for a not-so-simple definition. Just about everyone who has lounged around the aft-decks of dive boats for a season or two will have heard the term Pony Bottle to describe a variety of small scuba cylinders – all a sort of perfect copy of a full-sized cylinder but looking as though they were put through a hot wash and dry cycle and shrunk – and used for a variety of tasks.

Other names for these mini-cylinders include sling bottles, stage bottles, buddy bottles and a half-dozen or so more equally descriptive names. As with so much that has to do with scuba (for example, what IS the definitive definition of technical diving, these days?) there are few unbendable rules when it comes to words and phrases describing pieces of dive gear. A classic example is a pony bottle. I like to tell people that it can only be used for a small cylinder used as a backup air source… exactly what we are talking about here. Of course, that is not absolutely true, but between us, let’s make it so.

Now let’s assume that we have decided that having a backup source of gas is a good plan, and that the most practical way for us to carry that gas is to use a pony bottle, there are three more questions we need to answer.

The first is how much backup gas is enough?

Well, the short answer is enough to get us back to the surface. But how many litres or cubic feet is enough. Let’s do some basic calcs using an average consumption rate and an ascent speed that will keep our personal dive computers happy as clams. Let’s also pick a depth that is on the fringe of recreational sport diving: 40 metres or about 130 feet.

We start with a gas consumption rate of 15 litres/0.5 cubic feet  per minute. (By the way, the imperial and metric measures use in this example are NOT a direct or exact conversion. Close but rounded for convenience. ) Let’s also say that if we have to “bailout” to our pony bottle at depth, we are going to be a bit freaked out – Murphy does that to divers – and therefore our consumption rate is going to be doubled. So we can use 30 litres or one cubic foot per minute.

Our depth has a direct relationship to the density of the gas we breath so at 5 bar/ata (40 metres or 130 feet), we will use about 150 litres or five cubic feet per minute!

Also, let’s make some allowance for fiddling around at depth for a couple of minutes before we start heading back to the surface. How many minutes exactly is tough to guess, but it would be a mistake to think that we would start to head up immediately we detected a problem and bailed out to our pony. It would be nice to think that’s the way things would unfold but the truth is it takes time to get our buddy’s attention, get ourselves calmed down, sort out our gear and start the swim home. Initially, let’s calculate that we stay at depth for three minutes.

Three minutes at our depth and stress adjusted consumption rate requires 450 litres or 15 cubic feet of gas. (Wow that immediately rules out one of those Barbie-sized tanks doesn’t it?)

Now we can look at the ascent itself. In an emergency, the hard-wired, natural response that kicks in is the aptly-named flight, fight or freeze response. In diving, we have to resist flight, forget about freeze and fight to remain controlled and panic-free. As such, our ascent rate must be unhurried and moderate.  My personal computer is a fourth generation model controlled by a later version of the VPM algorithm, and as such the controlling ascent speed is about 9 metres or 30 feet per minute. Let’s use this speed to get ourselves from 40 metres / 130 feet up to six metres or 20 feet for a five-minute safety stop; which is once again a conservative choice. This gives us a smidge less than a four-minute travel time. We can round up again and make this a full four minutes. (In fact my computer would serve up a variable ascent speed causing us to slow down to about 3 metres or ten feet per minute for the last few metres approaching the safety stop. But we can ignore that in these calculations: and I will explain why later.)

To establish how much gas we will get through during that four-minute swim from depth to the safety stop, we have to know our average depth. The halfway point between 40 metres/130 feet  and six/20 feet  is 23 metres/75 feet  which gives us 3.3 bar/ata. From this we can calculate our gas needs as: 30 litres X 3.3 bar X four minutes;  or 5 cubic feet X 3.3 ata X four minutes. That’s around 400 litres (396 rounded up) or 14 cubic feet (13.2 rounded up).

So far, we need 450 litres at depth and 400 litres to swim to the stop, which adds up to 850 litres. For the imperial crowd the required gas volume is around 30 cubic feet (actually 15 + 14 for 29 cubic feet. A note: if you are doing actual calculations to translate from imperial to SI or metric on the fly, there is some slop in the numbers quoted here because of rounding errors and soft conversion values. The differences though are moot and the principle message remains the same.)

Now we have to spend five minutes at the safety stop. Using our base consumption rate as a guideline, our diver will use around 240 litres or eight cubic feet, and we can round those numbers up to cover the slow ascent from the stop to the surface. (The numbers are 1.6 bar / ata X 5 minutes X 30 litres / 1 cubic foot.)

Looking at our total gas requirements from the bailout at maximum depth then, we have:

450 litres / 15 cubic feet on the bottom; 400 litres / 14 cubic feet for the swim up; 240 litres / 8 cubic feet for the safety stop.  This adds up to 1090 litres (let’s call that 1200) or 37 cubic feet.

Before moving on to touch briefly on some issue that fallout from discovering just how much gas we should think about carrying, let’s make a couple of things clear.

In the calculations used here, we have been conservative with the baseline per minute consumption figure. At least half the divers reading this article would use less than 30 litres or one cubic foot per minute as a working surface rate. However, the other half would probably use more. And by the way, these numbers do work better if you plug in your personal SAC (Surface Air Consumption) and a factor modifying that volume to account for stress based on your abilities and needs, but frankly, our conservative baseline is a REALISTIC average.

Also, we have maintained the “high” per minute consumption rate for the whole of the swim to the safety stop as well as for the safety stop itself. In all likelihood, a diver who has him or herself under control would begin to “breathe easier” as they arrived at a shallower spot in the water column with their circumstances starting to brighten. Using a stressed consumption rate throughout the dive has resulted in a high total gas volume requirement. However, we have not factored ANY gas for a swim back to an ascent line at depth, we have factored nothing in for holdups while ascending, and nothing for blimps in procedures.

We have also opted for a slow ascent followed by a five-minute stop at six metres or 20 feet. We could just as easily have computed a faster ascent speed and a stop at three metres or 10 feet for three minutes. The resulting consumption figure would have been slightly less. However, a controlled normal ascent and a five-minute stop provides a better edge against decompression stress in this scenario I believe.

Finally, we have worked out all these numbers based on a dive at the very fringe of sport diving. A 40-metre or 130 foot dive is the maximum sanctioned for a sport diver with special training. Not all sport dives go this deep. However, in more than 20 years teaching divers about the basics of dive planning, — and being downright lazy –I’ve discovered that using a pinnacle dive (one that’s at the far boundary of what’s best practice for your experience and the maximum for your training) to calculate contingency needs follows perfectly the axiom of calculate once, use many times. In other words, if we follow these guidelines and then bailout from a shallower dive, we should have more than enough gas, all else being equal.

Clearly, the default sized pony bottle would be something that can hold this much gas. A decent choice in my opinion is a 6 litre / 40 cubic foot aluminum bottle. There are a couple of companies making this sized tank and they are relatively easy to find in local shops. Also, this tank has pretty good buoyancy characteristics in the water, is easy to handle, with a little pool practice behind you, and is simple to carry with you in the water.  The important thing is that fully charged, it carries ample gas for the purpose it’s being used for. There is the whole issue about whether to have it piggybacked on one’s main cylinder, carried as a sling bottle (classic North Florida Cave Diver rig) or as a sidemounted bottle (my personal favorite because it is out of the way but accessible), but let’s leave that debate for another article. Instead, let’s look at what type of gas would be the best to carry and why.

The simplest and most straightforward choice would be to always carry in your pony bottle EXACTLY the same gas that you have in your main cylinder. But this does require us to be wary of a potentially fatal mistake. For example, last week, hypothetical diver Jillian was diving a wreck on which an EAN38 was perfectly suitable, and she had her main cylinder and pony filled with a nitrox 38. Everything on her dive was perfect and the pony stayed unused. She does not bother to drain it. This weekend, she and her buddy are going to dive a reef and intend to take a photo of an Elephant Ear Sponge at around 40 metres or 130 feet.  At that depth, her pony bottle mix is hot delivering an oxygen partial pressure of 1.9 bar / ata. This is problematic.

A simple fix is to have the pony filled with a gas that CAN be breathed on a pinnacle dive. For Jillian or for the rest of us non-hypothetical divers for whom the specter of oxygen CNS toxicity is a real one this would be a mix containing 28 percent oxygen, which delivers a ppO2 of 1.4 bar / ata at depth.

The principle of diving with a bailout bottle or redundant gas source is a sound one. Many divers opt to follow the practice. It gives a diver – and that diver’s buddy – options when things go pear-shaped at depth, and allows for a controlled, independent ascent (by which I mean an assent where we are not tethered to our buddy by their octopus).

As with ANY procedure that’s outside the classic stuff taught in most open-water sport programs, there are a few “good to know” knowledge nuggets focused on pony bottles:

1) have the valve and hand wheel within reach, and practice breathing from the reg while feathering the valve.

2) fit the regulator with a full-sized SPG and check it before every dive.

3) pre-breathe the bailout regulator before every dive.

4) drill bailouts often until the process become natural and fluid.

5) mark the cylinder contents and check MOD before every dive.

6) have the hose for the pony bottle second stage long enough to reach your mouth (and your buddy’s)easily. A 40-inch hose is a good start, longer is usually better.

7) at least a couple of times each season, practice a complete ascent breathing from your pony bottle.

8) splurge on a good quality regulator for your pony bottle. It has to perform when you may be under stress.

9) treat your pony bottle system as life-support. Get the components serviced and checked on exactly the same schedule as your main cylinder and reg.

10) NEVER, NEVER, NEVER use the gas volume in your bailout bottle or pony in the gas calculations for a dive. In other words, do not plan your dives around the 1200 litres or 38 cubic feet you have in the pony. That gas is a RESERVE and should be ignored in one’s principle dive plans.

Although not the law, the best general advice for ANY single-tank diver who wants the assurance and personal “cushion” that comes from carrying a pony bottle, is that they  would do well to get some face-to-face time with a good mentor or instructor familiar with the kit and the procedures governing its use.  An excellent certification course on this score is the SDI Solo Diver Certification.

Steve Lewis ( is an active instructor-trainer with TDI/SDI and has written scores of articles on dive safety and skills development and is a regular contributor to several online magazines and discussion groups. He occasionally dives “open-circuit with a single aluminum 80” but never without a pony bottle by his side filled with a lean nitrox. His best-selling book called “the Six Skills and Other Discussions” is available at select dive stores and through onLine stores such as Amazon and Create Space eStore via:

Hi, my name is Bill and I’m here to help…

What exactly does Hogarthian mean?

“Man has such a predilection for systems and abstract deductions that he is ready to distort the truth intentionally, he is ready to deny the evidence of his senses only to justify his logic”

Fyodor Mikhaylovich Dostoyevsky, Russian Novelist: November 11, 1821 – February 9, 1881

Well a whole generation ago, if you were a cave diver hanging out in North Florida, you knew exactly what a Hogarthian rig was. You might not have agreed with it, but you knew who did, and the way they rigged their kit before going for a dive was easily recognized. Crap, you could even dive with the guy who lent his name to the system: William Hogarth Main.

In the interim, what used to be a pretty straightforward definition has become disturbingly fuzzy.

In the overall scheme of things, there’s no big deal in the kind of change that inches closer and closer to clarity, but I’m not a fan of change that moves in the other direction. Accordingly, indulge me today if I whine a little about a good idea gone wonky. Oh, and while we’re at it, let’s try to get a few historical ducks to line up in a row.

Let’s start with the ducks. Bill Hogarth Main is a real guy. Contrary to the views recently expressed in an onLine scuba forum by a newly minted tech diver and self-acclaimed “DIR Practioner” (whatever the heck THAT may be), Bill Main is not some fictional figure created to frighten the meek into conformity. He is just a guy who has been cave diving for a good while and, as far as I know, he still guides at a couple of select caves in North Florida, where he makes his home.

Hogarthian Gear Configuration is named after Bill because it is based on his minimalist approach to kitting up for a dive. Hogarthian has been referred to as the Zen of Cave Diving. Not a bad definition really since the Alpinist Way or Approach to any active, high-stress, high-risk sport is commonly linked to Zen. (I must add that as a Buddhist convert (maybe especially), this coupling is a mystery to me, but let’s leave it alone for the time-being and move on.)

When the concept was introduced to me, the principles seemed VERY straightforward and abundantly clear: Hogarthian kit was simple, serviced, standard, shared, suitable, and streamlined. I can still see my cave instructor standing in front of a white board with those words scrawled on it.

Before we continue, allow me to expand on those points just a smidge.

SIMPLE: nothing convoluted or contrived, and if something can be shaved off, filed down, or trimmed, do so. An example of simple: a piece of kit that can be fixed properly with stuff available from a hardware store. (This was explained to me when discussing dive lights with Bill Main and Lamar English back when I had hair.)

SERVICED: pretty easy to get this one straight. Nothing goes into the water as life-support that is not in working order.

STANDARD: you and the other members of your dive team have agreed on the appropriate kit for your dive and each of you therefore knows the operational niceties (and limits) of those tools.

SHARED: your buddy has your six-o’clock (your arse if you are only familiar with digital time-pieces). This principle can be applied to most of what is taken and what is needed in the water, but the FUNDEMENTAL thing shared is GAS. Tech divers follow gas rules that dictate that a portion of the gas in my tanks belongs to my buddy.

SUITABLE: if you do not need it, do not take it. More importantly, if a piece of kit was never intended or designed to cope with the environment you are going to take it into, resist the urge to push its functional envelope.

STREAMLINED: now this should come as no surprise to anyone who has read a book on technical diving. Short version: do not look like a Christmas tree, get rid of danglies, and aim for minimal resistance when swimming. I was once called on this score by Bill Main for wearing a drysuit to go cave diving… wow, that really is a shocker, isn’t it?

At some point, the definition Hogarthian got high-jacked and people started to apply it to kit choices and configurations that were many zip-codes away from what started out as a good idea. There is certainly nothing wrong with progress, and smart innovations in industrial design, electronic engineering, and materials manufacturing have made fools out of many of us who said: “I’ll never do that!” But I am not sure that moving away from the six basics that originally defined Hogarthian Configuration constitutes good thinking or best practice.

Those six guidelines actually hold true as much today as they did in the 1980s and early 90s when they were developed. As a CCR and OC sidemount cave diver I plead forgiveness for some of the choices I make, but I like to think that my diving philosophy is supported by those six “S” words.

Certainly when I look at divers who have adopted the more or less standard North Florida Cave Diver’s Kit consisting of back-mounted doubles, isolation manifold, wing/backplate, long-hose, bungeed backup, and a drysuit, the vestiges of Bill Main’s ideas are there… under the surface in some cases but the smell and taste remain.

What disturbs me though is that as functional as this layout has been, and how ubiquitous it has become in the technical diving community the world over, it is neither a perfect solution, nor does it conform to several of the basic tenets of Hogarth’s “Zen Outlook.”

Certainly to label it as “Right” or the best option available confronts the one principle of Hogarthian configuration that I neglected to add to the list above. I saved it until last because I feel it is the most important and deserves to be here at the end.

And frankly, without it, all the rest falls apart. What is it? Just this: Constant focus on improving the system, because nothing is perfect.

Thanks for your attention. History lesson over.

Accident Analysis (take two)

Enroll in any high-risk, high-stress endeavor, and the chances are that one of the first topics your instructor will throw into his or her opening conversations with you is how many ways you can kill or hurt yourself doing what it is you just signed up for. The first steps in just about every training program in the “adventure” category of things to do – from flying a plane to shooting a gun (at targets or bad guys) or climbing rocks or heli-skiing – will walk the activity’s newcomers through potential pratfalls. It’s a kind of universal mantra: learn from the mistakes of others.

Diving courses, well, certainly ones aimed at imparting skills for technical diving, work in a similar way. The politically-correct term used in the industry is Accident Analysis, and the framework for the AA modules I have been taught, worked with, or developed and written over the years follows closely the one first constructed and then refined for teaching cave diving. In its shortest form, an Accident Analysis module boils down to three stages: here’s some advice about what works, here are some examples of people ignoring that advice, now can we agree that they were stupid and that we will try not to follow their example.

For the record, here are three real-life scenarios that got people killed. I share these with tech students. See what you make of them.

Scenario one: August, 2009. Three experienced sport divers attempted a deep dive off the coast of California. The participants were a dive-store owner, his friend, and a 22 year-old shop employee and DM. Although the trio had done similar dives before, none was certified beyond sport-diving limits. The dive shop involved did run tech programs, but they were overseen by a third-party instructor. Worth noting is that this individual was NOT part of planning the dive in question and was apparently not involved at all. By the way, the dive was planned to be around 60 – 65 metres using air as back-gas. It turned out that the actual dive’s depth exceeded the plan at 70 metres plus. During ascent, the “team” lost contact with each other and the 22 year-old man was seen drifting away from his dive “buddies” and was sinking. After some time, his body was found on the surface.

Scenario two: November 2009. Two divers attempted to dive Eagles Nest on CCRs. On a previous occasion, the pair had been taken to the “cavern” area of the nest by an instructor teaching them a course on CCR which they did not pass. For the record, one must apply a very liberal definition of Cavern to describe any part of the entrance to Eagles Nest, an extensive and very deep (80 metres plus) cave in Hernando County, Florida. Also for the record, neither man was cave certified, nor was the instructor who had previously taken them to the cave for training dives, a cave instructor. During their ill-fated final dive together, the two CCR divers had opted to use a diluent in their rebreathers was hot for the depth they attained (reportedly one containing 18 percent oxygen). If this were the case, it would have made impossible at depth controlling their setpoint (partial pressure of oxygen) at recommended levels of 1.2 or 1.3. Also, a meaningful diluent flush, cell test would have been impossible. At some point, approximately 170 metres from the cave’s entrance area, one of the divers experienced difficulty and died. His body was recovered in one of the deepest sections of the cave some time later by a team experienced in deep-water body recovery.

Scenario three: In mid-November 2008, the bodies of two divers were recovered from Wayne’s World (aka School Sink), Pasco County, Hudson, Florida. Wayne’s World is considered an advanced cave dive yet only one of the buddies had ANY overhead training, and that was only an Intro-to-Cave card – well shy of what’s recommended to dive this site. The other diver carried only an Advanced Open Water certification. Both were wearing traditional North Florida Cave Kit with decompression gas. Recovery divers discovered both bodies within 80-90 metres of the cave entrance. Their bodies were separated by approximately 30 metres distance. One was found at a depth of approximately 14 metres with his oxygen decompression gas deployed (oxygen is considered highly toxic if breathed deeper than around 6 metres). The other was deeper in the cave, dead on the ceiling showing signs of distress. During inventory of the dead divers’ equipment, this diver was found to have his isolator closed with one cylinder empty and the other containing at least 3500 psi.

Here are the questions I use to begin the analysis process in the classroom.
Where did logic chain begin to break down?
What simple guidelines seem to have been ignored in these cases, and how might ignoring them have contributed to the seriousness of the situation these people found themselves in?
In all three cases outlined, whom do you feel should shoulder some responsibility for these deaths?


Of course, by its nature, this exercise is speculative since the process asks us to form conclusions based on a sandwich made from a couple of slabs of conjecture and a thin layer of fact. There is also a complex moral issue with us forming a judgment about someone’s behavior – which inevitably happens – without their input during our deliberations. After all, there may be rectitude in their behavior – although on that last point, experience does tend to suggest there are no fixes for stupidity.


However, all that aside, the exercise serves a purpose which is not to allot blame but rather to identify errors, understand how easy it is to mess up and from that deductive analysis, avoid repeating the same mistakes ourselves.

There’s one other shortcoming. Between you and me, I dislike using the word Accident to describe many of the examples we use to point out the kind of behavior that results in diver deaths.

What is an accident?
One definition of an accident is “any unplanned event that resulted in injury or ill health of people, or damage or loss to property, plant, materials or the environment or a loss of business opportunity”.
That’s OK as far as it goes. Certainly unplanned seems to be the pivotal point, but it begs some further investigation… and definition surely. Let’s take for an example scenario three above.
It’s well known that diving in a cave without training is a poor choice. Did the two guys who died know that diving without training, experience and kit in a cave was a poor choice? Sure they did. There’s a bloody great big sign to remind them at the cave entrance. They planned to dive ignoring that fact, and I’d wager the general consensus from fellow divers would agree as inappropriate using a definition that includes the term “an unplanned event” to describe their actions.
Given the circumstances of their dive, their behavior was risky: they took a risk and their calculations – whether conscious or not as to how likely their choice was to backfire and kill them – was incorrect. They screwed up, assuming naturally that their intention was not to kill themselves. Think about this: One guy had around half his back-gas available. All he had to do was switch regs or reach back and check his isolator. Yet signs at the site of his death indicated he drowned.
Is deciding to take a risk and miscalculating its inevitability an accident? Is ramming into the back of a parked car at high-speed with an alcohol level above the legal limit for a driver – whatever that limit may be – an accident? Surely it’s recklessness, carelessness or criminal. What do you think?
The Brits use the term “death by misadventure.” For the record, the definition of this phrase in Webster’s is “a death due to unintentional accident without any violation of law or criminal negligence. Thus, there is no crime.”
Death by misadventure does have a nice ring to it: no blame, just a couple of guys out on a lark that went wrong. Is that how you see scenario two, or is there more to it.? Is there some level of culpability, negligence?
A buddy of mine tells his students that cave diving is deceptively easy.

“Anyone can swim to the back of a cave,” he says. Another buddy tells his students that “Even an open-water diver can make a dive to 60 or 70 metres.” They also add that their statements are only true until something goes wrong. In a pear-shaped world, it’s finding the way out from the back of a cave or getting back to the surface intact from 20 storeys down that presents problems.


When things go wrong underwater, the fundamental skill becomes survival. In diver training, this is broken down into three major tasks:
• control the natural fight or flight (or freeze) response
• suppress panic
• work on getting your ass back home (This latter skill requires critical decision-making, physical and mental actions involving some level of multi tasking, which some people can do, and some cannot.)
The ability to react appropriately when things fall apart is an acquired skill even for those who have some natural abilities and the skills to survive. It takes knowledge backed up by experience and practice. How much of each is a hugely debatable point, but I believe the diving community as a whole agrees that it takes more experience and practice than one can gain during the average technical diving class… even when full knowledge of what to do and how to handle the situation has been taught.
Well, that’s a shocker, isn’t it? We certify divers to do dives but we believe they may need more experience and practice before they can survive something going pear-shaped!
If this were the case, our beaches would be littered with the dead and injured and clearly they are not. Most people leave a dive class – regardless of whether it is a sport diving or tech diving class – with a full understanding that what they just earned is an OK to go out into the real world and gain experience and practice, gradually. They have the knowledge to do so well within the limits of their training. And that is the key… within the limits of their training. Without training or with a disregard of what that training taught, all bets are off. They have no knowledge and are unlikely to live long enough to gain wisdom.
So what is the bottom line, take-home message from Accident Analysis?
I’ve always reckoned it to be the advice to take things slowly, to be cautious, and to stay within the boundaries of your comfort zone, which are the actions of a wise diver. What does Accident Analysis say to you?

Zero-to-Hero… there are no winners in training shortcuts

If all you can think of when you read the phrase “Zero to Hero” is a British post-punk band, hats off to yer! However, chances are that as a diver, the phrase has other connotations: far less entertaining.

I really have no clue where and when the Zero-to-Hero epithet was first applied to diving. I heard it around the time that the whole concept of technical diving and especially technical diver training began to enter mainstream dive-community awareness, sometime in the early to mid 1990s. At that time, Zero-to-Hero was applied specifically divers who miraculously leapfrogged from newbie to expert seemingly overnight.

It worked like this: a small core of instructors and dive shops started to advertize “boot camps” that promised punters some form of guaranteed certification at the end of a week or so of “intense training.”

An example from that time was a seven-day “mega-course” that swept candidates – advanced open-water divers who carried no technical certifications or experience — to trimix certification by the time the circus wrapped up. (For the record, this meant guaranteed certification to conduct full decompression dives on helium mixes with exposure up to 60 metres deep.) I believe the prerequisites to sign-up for these programs included having a pulse, a checkbook, and a broad gullible streak.

Gullibility? Well, at issue was the obvious. If one looked closely at some agency standards, it was just about possible to cram into a seven-day period, the required classroom, confined water and open water dives. Possible yes, but far from desirable… and certainly could not possibly carry any guarantee that participants would have earned their certifications at the end of it.

From a training agency perspective, this type of course barely met the letter of the law, and certainly bent the spirit of it into the shape of a banana. What was missing from the equation was experience. The poor punter would find himself or herself dragged into progressively more complex dives  day after day without any time to catch their breath or reflect on the lessons to be learned. They would be taken at lightning speed with little time to ask questions – or more importantly, discover answers – as they progressed rapidly from a normal dive plan that consisted of a quick “Let’s go diving…” to something that would help protect them and give them the tools to ascend from water deep enough to cover a 20-storey high-rise.

At the end of their “intensive training” they would have completed a handful of staged decompression dives under the auspices of an instructor –and auspices is about as apt a term as possible to describe what would have been going on for seven days. Unfortunately, playing follow-the-leader on what was essentially a guided, trust-me dive does not constitute technical diver training.

The certifying instructor’s crime – if functioning without a moral compass can be classified as such – was that when all was said and done, they handed out cards which stated the holders were capable of doing the same dives at some future date without the help of a baby-sitter.

I worked on the Training Advisory Panel of a large agency at the time and, like many of my peers, felt there was something wrong with that. Apparently, we were not alone, and to my knowledge, the temptation to promote this sort of fast-track program for John and Jill Diver was pistol-whipped out of the rank and file tech instructors by many of the major, reputable tech agencies. In addition, the market, divers who were expected to buy-into the concept, quickly realized that Zero-to-Hero type training was not a sound investment. Today, this fast-track practice has fallen out of favor in the tech arena: or has it?

One of the companies for whom I do consulting work, makes rebreathers: the fully closed-circuit kind. The data suggests they are the market leader world-wide… or very close to it. Certainly their brand is well-known and highly visible in the technical market.

Rebreathers are tech, correct?

Well, the dive industry is nothing if not dynamic and that’s changing. Several manufacturers – including the one I work with – are in the middle of readying themselves for a minor market tremor that promises to open rebreather diving up to sport divers.

Given a couple of provisos, I do not believe there is any real problem with that. Diving rebreathers is fun, and with real prerequisites met and enough time for practical work, a sport-diver CCR course will probably work. It will be hard work for everyone involved, but not impossible to organize and probably a whole lot of fun to deliver!

Provisos met.

The only thing that bothers me a little is that this new market opportunity – and that’s how it’s being billed within the professional segment of the dive industry – feels like an opening for the Zero-to-Hero can of worms to open up all over again. Only this time, it’s not the punters I worry about… it’s the instructors who will be delivering their training.

Most CCR manufactures have a unique power when it comes to who teaches on their units. You might think of it as a special veto. An instructor candidate (regardless of if their agency believes them ready to teach) has to be given the OK to conduct training classes by the manufacturer of the unit he or she wishes to teach on. Part of the minimum prerequisites held to by the major rebreather companies is that the instructor candidate must have logged 100 hours on the unit.

There is nothing magical about 100 hours experience flying a CCR; except it takes a while to accumulate. Also, although it does not guarantee much, it is highly likely that during the accumulation of AT LEAST 100 logged hours in the water, the majority of divers will have learned some important lessons about their unit and themselves.

CCRs work just fine… at least the two I dive seem to… but all rebreathers are unforgiving of sloppy procedure and short-cuts. Most divers will experience one – sometimes more than one – “come to Jesus” moment during 100 hours of operation. The most essential lesson they will learn is not that their unit malfunctioned, but that they dropped a stitch and the culprit is HUMAN ERROR. They will develop a visceral understanding that they were at fault.

You can read all about human error and lack of situational awareness in a book – damn, I’ve written about it myself – but the words tend to leap out of your memory and grab you around the throat when you are at 60 metres and recall that you did not do a thorough pre-dive check: and that gurgling sound is not because the rebreather was designed incorrectly. Operator error is a great teacher, and a very fine learning tool.

So, what’s the problem? Simple, really. We can expect a lot of interest in rebreather training during the next few years as this whole Sport Diver Rebreather thing hits the market, and there is going to be a temptation for instructors to “get in on the action.” I have already heard instructors selling the concept to their students. However, few of them have any experience diving rebreathers, and more to the point, do not seem to comprehend that a rebreather is unlike any piece of open-circuit kit and no amount of time on open-circuit translates to running a CCR life-support system. My fear is that some instructors may fudge their logbooks in order to attain instructor status in the shortest time possible. There are some checks and balances in place, but there are ways to cheat them too.

I may be alarmist and all this concern may be unfounded. But please, if you or someone you care for is thinking about making the switch to a rebreather, be very, very careful that you avoid any whiff of Zero-to-Hero in your instructor: regardless of the agency they teach for or the unit they teach on.

Cardiac Stress Testing and technical diving

Around this time every year, most of us hang up a new calendar, and polish up the New Year’s Resolutions. Like me, you probably have a few left over from last January 1. If you do, chances are good that one revolves around “getting fitter,” “getting in better shape,” or “working off all that Christmas pudding.” If that is the case, and you’re a diver, I’d like to suggest adding a slightly different twist for 2012.

During a few recent and very informal discussions with other tech instructors, one of the highest-ranking concerns has been the number of divers – particularly tech and rebreather divers – who have died of heart-related problems either while diving or soon after diving.

There are all kinds of issues that may have had an influence on incidents in the past, but the collective concern was how to help make 2012 a “better year” for the dive community.

One idea floated out was to ask students* to undergo a cardiac stress test as part of the list of prerequisites that need to be met before enrolling in advanced technical programs, such as CCR, trimix and advanced wreck and cave.

A cardiac stress test stimulates the heart – either by exercise or with intravenous pharmacological stimulation – and connecting the testee to an ECG. The American Heart Association recommends this kind of testing for patients with medium risk of coronary heart disease. This includes folks with personal risk factors such as smoking, a family history of coronary artery stenosis, people with hypertension, and folks dealing with diabetes and high cholesterol.

Who knows if it would make much of a difference, but what harm would it do? I’m old and get one for free every year through my insurance (BONUS!), and there is a level of comfort knowing that there are no serious issues with the old ticker.

I believe the cost of a cardiac stress test works out to about the same as the charter fees and fill costs for an open-circuit deep wreck dive. Worth the dough? I think so and certainly worth adding to that list of resolutions… Things to do in 2012!

* Students who have risk factors, or those 45 years and older.

Helitrox Decompression… class notes

What you need to know about Helium
(a supplement for techdiverTraining Helitrox divers)

As a Helitrox Decompression Diver, there are a few things you should know about helium, this new gas you can now add to your scuba tanks, since your TDI decompression procedures textbook does not cover this topic at all. Luckily, the vital stuff – the things you need to know to help keep you happy – can be summed up in a couple of pages. Please read on!

We can start off by looking at some of helium’s properties.

Anyone who has organized a kid’s birthday party and bought party balloons already knows helium gas is lighter than air: it’s actually many times lighter than air. For those with an interest in these things, a mole of helium has a mass of 4 grams compared to 32 grams for the same quantity of oxygen and 28 grams for the same amount of nitrogen.

Just in case you forget your high-school science, a mole is measurement of quantity – a specific number of elemental particles or molecules – used in chemistry. For example, a mole of Ideal Gas has a volume of close to 22.4 litres at STP (Standard Temperature and Pressure – 0 degrees Celsius, and one atmosphere or 101.2 kPa). An ideal gas is defined as a hypothetical gas in which all collisions between atoms and/or molecules are perfectly elastic and in which there are no intermolecular attractive forces. This is unrealistic behavior for a gas but we use it in diving because diving is not an exact science. In the context of diving, we can say that 22 litres of helium weighs 4 grams compared to around 29 grams for 22 litres of air.

Is any of this really vital to you as a Helitrox Decompression Diver? Nah, not really. However, it does help to show us why a cylinder filled with trimix, has buoyancy characteristics that are different to the same cylinder filled with air or oxygen: it has a tendency to float, the oxygen cylinder does not.

One other issue that relates directly to the mass of helium is work of breathing (WOB). The deeper we dive, the denser our breathing gas becomes and pulling a lung-full of gas into our body requires more work and effort. Using air or nitrox, you may have already noticed that your regulator – which performs perfectly at 20 or 30 metres – starts to feel a little “tighter” as you venture past 40 metres (132 feet). The WOB, even on a well-adjusted, high-performance regulator, increases noticeably as we descend deeper than 60 metres (200 feet). This increased workload can play a major role in carbon dioxide build-up in a diver’s blood, which of course affects respiratory function.

In short, gas density affects a diver’s comfort, safety and performance. Adding helium to our bottom gas effectively thins out that gas making it easier to breathe at depth. With 20 percent helium in your back gas, you may notice your regs have never breathed easier!

Back to our high-school chemistry for a moment: Helium is a member of a handful of elements known as Noble Gases. The term “noble” probably comes from the fact that these gases have their outer electron shell completely filled, and this makes them (Helium, Neon, Argon, Krypton, Xenon, and Radon) “aloof” and in most circumstance, nonreactive or inert. Noble gases do not bond with other elements. Helium is pretty typical in that it does not burn, does not mix with other substances to form stable compounds, and – as with its noble gas bunkmates – is monoatomic; in other words, it does not even like to associate with itself and hence we write ‘He’ and not ‘He2‘ as we do with O2 and N2. The behavior of helium as a Noble Gas is only a concern to us as divers when we need to make exact calculations to mix gases accurately. Coles Notes version: for a given pressure and temperature, one gets less He in a scuba cylinder (fewer moles) than air or oxygen (i.e. 200 bar of helium is NOT the same as 200 bar of oxygen).

OK, so notwithstanding the all of the points outlined above, one basic question remains: Why do we use helium? I am not trivializing the importance of floaty bottles, lessened WOB at depth and how many moles we can cram into an aluminum “80”, but what else is there to know?

Probably number one is that helium is – for the purposes of diving at depths attained by recreational technical divers – biologically inert. Since it is not narcotic and non-toxic, it makes a great diluent for nitrogen and for oxygen. Adding helium to keep the partial pressures of both those gases to manageable levels is the real reason for this course. Your classroom notes should include the basic “Dalton’s Law” calculations for the suggested bottom-gas mix to be used on the pinnacle dive for this course… a 30 minute exposure at 45 metres (150 feet).

Just in case you do not have those notes handy, here is the short-form:

Ambient pressure at depth of 45 metres = 5.5 bar

Target Oxygen Partial Pressure at depth = 1.30 bar

Target Nitrogen Partial Pressure at depth = 3.16 bar (same as air at 30 metres)

Vacant partial pressure (Ambient – (O2 + N2) = 5.5 – (1.3 + 3.16) = 5.5 – 4.46 = 1.04

So, we have to fill 1.04 bar with something other than oxygen or nitrogen to keep the levels of those two gases within a tolerable range. Easy, we can use helium because it is a “diver-friendly” gas.

Now, at some point, we have to let someone at a dive shop know what flavor of trimix (or Helitrox) we want them to mix, and so we need to convert partial pressures in bar to a percentage of the ambient pressure. In other words, we need to calculate the ratios of each of the gases used.

Here are those calculations: 1.3/5.5 x 100 = 23.6% Oxygen; 1.04/5.5 x 100 = 18.9% Helium; 3.16/5.5 x 100 = 57.4% Nitrogen (rounded numbers which do not quite add up to 100%).

I am not sure what the folks are like where you buy your fills, but I could not bring myself to ask my supplier for a mix with fractions such as 23.6 or 18.9. It makes more sense to round the numbers up to whole numbers, let’s say a 23/20, and that is what I would dive. For the record, TDI suggests the mix for this class at this depth cannot exceed a 25/20. I cut back on the oxygen pressure just a little because I believe it better suits the water conditions where I do most of my diving.

OK, just two more small issues to deal with. The first is perhaps the biggest myth surrounding dives using trimix. The myth is that ANY mix with helium is going to give a diver a much longer decompression obligation that diving air. This is patent bullshit. I simply cannot categorize it any other way.

Helium is said to have faster transit times than nitrogen in a diver’s body; it is absorbed and eliminated more rapidly than nitrogen. This does result in ascent schedules with a slightly deeper off-gassing ceiling, calling for running stops beginning deeper in the water column, but overall ascent times are shorter NOT longer. Here is an example that’s relevant to the type of diving you will do as part of the graduation requirements to earn certification.

A dive to 45 metres for 30 minutes breathing a 23/20 trimix and a EAN50 starting at 21 metres on the way up. Total runtime = 63 minutes.

Exactly the same parameters for the dive but substituting air for the trimix on the bottom and keeping the EAN50 deco gas for the ascent. Total runtime = 74 minutes!

OK, so perhaps there’s a difference because the trimix has 23% oxygen and air only has 21%. Here the same dive with an EAN23 instead of trimix and all the other stuff the same. Total runtime = 71 minutes.

No matter how you cut it, the ascent time on trimix is shorter. (By the way, the first running stop on the trimix ascent IS deeper by about three metres.)

OK, so with that myth busted, let’s move on. The final item is thermal stress and the role of helium in hyperthermia. Helium does a poor job of insulation and pure helium would make a very bad inflation gas for a diver’s drysuit. I have dived in a cave in 20-21 degree water using pure helium in my suit. It was not a wonderful experience: I strongly suggest you do not try it for yourself.

TDI suggests using an alternative suit inflation system to one’s back-gas when ANY helium is being used. This is a great idea if you are diving in an area with a marked thermocline; however, many divers diving in water 20 degrees and above, find very little thermal effect when using a gas with only a moderate amount of helium in it. During this course, you should not have more than one-fifth of your back-gas given over to helium. You may find it unnecessary to carry a separate drysuit inflation system in moderate to warm water conditions.

Oh, one last thing, sound travels about four times faster in helium than in air. One result of breathing helium is that it makes one’s voice sound like Donald Duck or Minnie Mouse. This Disney effect is really funny. However, be aware that pure helium or helium mixes that do not contain at least 21 percent oxygen, are dangerous and breathing them may result in hypoxia and death or serious brain damage. Keep helium away from kids!

Thanks for your attention.

Steve Lewis

TDI instructor-trainer

Omitted Decompression and In-water Recompression (IWR)… some thoughts

Occasionally, in fact with an almost predictably cyclic regularity, two questions that surface on the internet dive forums ask about missed decompression and/or in-water recompression (IWR).

My standard answer on a public forum is to suggest that when the diver shows signs or complains of DCS symptoms, notifying EMS, keep the diver on the surface, warm and hydrated, monitor for changes in their condition (a correctly conducted five-minute neurological exam is a decent protocol for this), have them breathe pure oxygen (preferably from a demand face mask), take notes that will be useful for EMS/Hyperbaric staff, and prepare for fast evac.

The suggested strategy for a diver who has omitted a “deco stop” or safety stop but is SHOWING NO SIGNS or who is NOT COMPLAINING OF ANY SYMPTOMS, is the same as above but without the call to EMS and rather than preparing for evac., collecting their kit for them and keeping them out of the water for at least 24 hours.

However, neither is a very good answer to the actual questions posed, and occasionally, I throw my hat in the ring… something like this.

The first step for anyone brave enough to attempt an answer is to define the differences between the two topics; and in particular, the circumstances that might necessitate the call for a diver to conduct an omitted decompression protocol, as opposed to those that indicate IWR as an option.

Let’s start with the easiest: Omitted Decompression.

The protocols for Omitted Deco are discussed and outlined in several technical diving student manuals – including a couple of TDI manuals – and the procedure is taught as part of TDI’s decompression and trimix courses. It is based on the protocol published in the US Navy Diving Manual and may only be attempted when the diver shows NO SIGNS and has no SYMPTOMS of DCS; and the omitted stop was no deeper than six metres.

There are a couple of other prerequisites relating to water conditions, weather conditions, thermal protection, available gases in sufficient volume, having a tender diver available to monitor the subject diver during the whole procedure, and the diver being in a position to return to the water within five minutes of surfacing.

All that as taken and confirmed: First, return to 12 metres and conduct the stop required at that depth by the original ascent schedule PLUS one quarter of the omitted three-metre stop time. If no stop was originally required, remain there for one quarter of the omitted three-metre stop time. Ascend to nine metres at a speed no greater than three metres per minute (the ascent speed for the whole procedure) and remain there for one third of the three-metre stop time. Ascend to six metres and wait there for half of the three-metre stop time. And finally ascend to three metres for one-and-a-half times the scheduled three-metre time.

Here’s the way that looks for an omitted or partially omitted deco stop at three-metres.

Depth (metres/feet) Original Stop (mins)/Gas Omitted Stop Procedure
12 metres/40 feet None/ bottom gas 3-minute stop
9 metres/30 feet 3 / bottom gas 4-minute stop
6 metres/20 feet 5 / oxygen 6-minute stop on oxygen if CNS allows
3 metres/10 feet 12 /oxygen (omitted) 18-minute stop on oxygen if CNS allows

For the record, I have tendered for divers who have missed all or part of a decompression schedule and for whom the missed deco protocol worked.

Now let’s attempt to clarify the issue of IWR. This is suggested when a diver surfaces and complains of symptoms (type one) and IWR is the ONLY option available… i.e. there is no hope of stabilizing them and getting them to a hyperbaric facility.

Important to establish first off that this is a highly risky endeavor. The risks of IWR include several minor issues relating to thermal stress and volume of gases needed, but the strong emphasis in the entire risk assessment analysis center on the subject diver getting worse far worse once in the water and becoming, for example, paralyzed and/or losing consciousness. Oh, and then dying.

Various protocols and tables for IWR have been developed over the years. The recognized tables include the Australian, the Hawaiian, the US Navy, and the Pyle tables… I believe Pyle’s modification to the Hawaiian table are the most “up-to-date.” I am reasonably sure that NONE carries sanction from the major sport agencies. The technical agency I teach for, that I do consultant work for, and on whose training advisory panel I served for several years, does not sanction IWR either. Essentially, within the context of recreational diving (tech or sport), IWR is simply NOT an option.

Just in case we wonder why, here’s a checklist of the minimum kit and personnel requirements for attempting IWR in a remote location.

  • A heavily weighted shot line secured in a sheltered spot where surface waves will not influence comfort of subject diver and/or the tender (who will be in the water) and treatment supervisor (who will be on the surface).
  • Some way to hold the subject diver in place… a climbing harness works as does a sidemount harness with some modifications
  • Stages in the shot line to hold the subject diver at a set position in the water column… prussik loops and a locking carabiner work if tied and anchored correctly.
  • Full-face masks with coms to the surface and each other
  • Surface supplied gas (oxygen et al) supplied to the subject diver via umbilical
  • An experienced tender and supervisor who have at very least certification and some background in hyperbaric treatment
  • Adequate and possibly additional thermal protection for both subject diver and tender
  • A valid IWR treatment “table”

As someone who is occasionally involved in expedition diving (the only situation I can imagine where the whole team would discuss IWR as part of the SOPs during pre-trip planning sessions), IWR is considered highly risky even when ALL the above, and a few more details, are available. It is also understood that IWR (just as recompression in a chamber on the deck of a boat or in a medical facility) may not resolve the issue. In other words, the subject diver may die.

The preferred option if a portable chamber is NOT AVAILABLE – and something many expedition leaders seem to have less hesitation using – is saline IV (intravenous) therapy, oxygen and the use of pain medication all administered by a practicing medical practitioner of some sort… NP, Paramedic, MD et al. It is therefore considered best practice to have at least one of these as part of the team on ALL expeditions to remote locations.

(For the record, I have been lucky enough to lead several expeditions to various spots where there may have been a temptation to use IWR, and I have certainly tried to make sure that at least one team member is an experienced diving MD. To date, one of my team has had to supervise an autopsy on one of our fellow team members, but we have not had to deal with IWR. Therefore, my first-hand experience in this issue has been ZERO.

You can read more at Gene Hobbs excellent online resource:


Dive industry trade shows… are they dead or just sick?

Comparable stats from other industries (in conjunction with DEMA’s figures) seem to indicate that the broad appeal of a “traditional” trade show is waning. There are some notable exceptions, but several years of experience watching attendance at and sales at DEMA suggest the dive industry is not one of those exceptions.

I had a unique opportunity this past November to visit Orlando and attend our industry’s biggest trade show wearing several hats. I was not tied down to one booth — as in past years — but wandered the floor, made several presentations, and generally “mingled.”

As a travel product marketplace, DEMA is sans pareil. However, despite some brave attempts at making a visual impact from many of the more mainstream scuba services (punctuated by several lack-luster booths from one or two major players), this year’s show showed all the vibrancy of an old dog too tired to play fetch. Saturday, for example, the show curled up and napped.

From conversations before the show, during and after, I believe the industry has faith in consumer shows still — albeit with a slightly updated approach compared to the old “put up a shingle and wait for the customers” — but a trade show as expensive, as regional, and as poorly attended as DEMA… well, the jury seems to be out.


N.B. DEMA stands for the Diving Equipment & Marketing Association.

View from a different vantage point

The gentle slope that stands between our sugar bush and the raised beds we use to grow veggies, is covered in white trilliums. Fact is the whole wooded area behind our house and down into the small valley that forms the southern boundary of our property is full of trilliums and trout lilies in early spring.

This indicates that our little corner of Muskoka is waking up from winter, finally, and is taking on the postcard picture beauty it is famous for at this time of year. Fittingly, white trillium is the provincial emblem of Ontario – where I live – and, just for the record, is also the state wild flower of Ohio. So my guess is that a lot of folks agree that trilliums are neat little flowers.

Usually I am not home to see them bloom. Most years I am away someplace diving, but this year is different; I am “on sick leave.” In the simplest terms this is a bummer.

On the upside of this situation, I uncharacteristically have the time to sit on the sidelines as spring arrives here in full force. And in between watching eastern bluebirds and tree swallows battle it out for nesting boxes, celebrating the early appearance of Ruby-throated hummingbirds, avoiding the attendant black fly hatching, and taking notes on the ongoing procession of wild-flower bloomings, I have had some time to reflect on what I do for a living:  teach and write about technical diving.

My forced inactivity is the result of an unfortunate early April convergence of two seemingly unrelated issues.

One is a result of back pain mentioned in an earlier blog, and the other being an unfortunate run-in with Epstein-Barr virus. Epstein-Barr is a nasty illness that goes by the common, rather insipid and nondescript, name of Mono. It is a rotten punishment for anyone, but especially so for those of us with an A-type personality.

My strategy for dealing with the first is corrective posture, yoga and physiotherapy, and to kiss goodbye to doubles and the ubiquitous North Florida Cave Diver’s Rig.

No more diving doubles for Doppler. After about 20 years of abusing my body marching around with the equivalent weight of a corps de ballet dancer strapped to my back, the spokesperson for my thoracic vertebrae has told me directly and unequivocally that it is time to concentrate on CCR and Sidemount.

The second insult to my well-being is not as easy to fix.

In fact, it promises to be a juggling act. But time and patience will win out. In the meanwhile, now that sitting at my desk and typing does not hurt, it’s time to share what’s next on my, to do list. It no secret to anyone involved in technical diving, that in the past decade or so, the limits of our sport have shifted outwards a fair bit.

New technology, gear designed specifically for extreme diving, a freely available database of ascent profiles that worked, a growing network of instructors willing and able to mentor interested divers, discussion forums et al, have all contributed in some way, minor and major, to this movement.

For example, ten years ago, there were few recreational divers who had visited 100 metres; in 2011 non-military, non-commercial, non-scientific divers around the world pull off 100 metre dives weekly if not daily.

Ten years ago, only the most experienced attempted a cave dive to the end of the gold-line in one of the “tourist caves” in North Florida, or a weekend charter to a 350 foot-plus dive site. These dives earned a mix of admiration and admonition. In 2011, we read about relatively new tech divers doing these dives and hardly anybody notices… or so it seems.

The odd thing, at least to me, is that so few dive teams employ in-water support divers to help make these deep, long dives a little more managed. Perhaps we need to do something about that situation.

Over the course of the next couple of weeks, I want to lay out some ideas I have for a new book specifically aimed at teaching and discussing roles and techniques for expedition support; because I can’t do much in the way of diving!I would appreciate your input. As much as I like looking out at the new season arrive, it is driving me nuts!

By the way, would appreciate your input on a small survey… You will find it here>>>DIVER SURVEY

The fragility of mobility: the curse of pain meds

I still am unsure what triggered things exactly, but a very unpleasant feeling in my upper back and arms started to make itself known one Sunday evening a few weeks ago. The best comparison is that it felt like a severe muscle cramp: but unlike a leg cramp this one was impossible to relieve. Over the next few days, the cramping made itself at home in a variety of bi-lateral muscle groups in my upper body.

After several worried visits to health-care pros of various flavors, resulting in CT scans, Doppler Ultra-sound investigations, blood work and lab tests, plus Chiropractic manipulation (ongoing), I am back to a point where I can sit at a keyboard and do what passes for work. But being analytical by nature (my family put the stress on the first syllable), now is the time for serious reflection: What happened, Why, and How can it be prevented from happening again?

Like many of you, I kid myself that my daily activities include enough stretching and flexing to keep my back in top shape. Again, like many of you and especially during the winter months, the bulk of my every-day chores revolve around sitting at a desk, tapping away at a computer, dialing a phone or standing at a whiteboard talking. The opportunities to bend, reach, twist and generally counter the effects of spending hours relatively motionless are few and far between. My principle non-sedentary work-related activity revolves around heaving equipment onto my back and lugging it to the water’s edge and falling in… or efforts to that effect. These underwater episodes are usually bracketed by long drives.

All in all, not the recipe for a happy back. In fact a very good recipe — perhaps prescription is a better word — for a very bad back, and that is what I’ve got.

But to look on the bright side, the events of my past few weeks have served as a graphic warning and compelling reason not to let this sort of thing happen again. I will be revisiting the frequency and intensity of my personal back-care program, and while it does look as though my chiropractor and I are going to be seeing a lot of each other, I can also see a yoga class in my future.

My best guess for the cause of all the trauma and pain and resorting to bottles of pain-killing meds is complacency. Over the past few months my workout schedule has sucked. And I am reaping the results. Mea Culpa.

Please learn from my example… stand up right now and stretch.

And by the way, my resistance to hard-core opiates such as percocet is low. They send me into a soft-edged landscape populated by characters out of a Robert Crumb cartoon with Jimi Hendrix playing the theme music. Only trouble with this seemingly ideal cop-out, it that to an outside observer I appear normal… according to my wife, more lucid than normal. And apparently at various points in the first week of this “back episode”, I engaged in long and detailed conversations with people in person and on the phone, and via email. I can remember nothing. At least the emails I can read, but if we spoke during the second week of April, do us both a favor and call me back!

Take care and dive safe… and exercise that back!

Come out and say Hi!: Presentations at ScubaFest

I will be making presentations at several consumer dive shows during the next few weeks, and it would be great to see some of you there.

ScubaFest is at the Crowne Plaze North in Columbus, Ohio and takes place March 18 through 20, and there are lots of workshops, presentations and exhibitions planned.

I’ll be at bat on Saturday from 10 until 11 in Salon E/F talking about Rebreathers. The title of my chat is Rebreathers: are they the solution you have been looking for? The aim is to show folks interested in CCR some of the questions they should be asking themselves and their instructor should they opt for CCR training.

On Sunday, in Salon C starting at noon and running for one hour, the topic will be Sidemount diving. My presentation gives a little background and covers some of the ways and wherefores associated with sidemount diving on wrecks and in cool openwater applications.

I hope you can make it!

More information about the show here>>>


P.S. Word is that I will be signing copies of The Six Skills at the show. Drop by and get your copy personalized.

Is CCR diving right for me?

I think most rebreather divers and certainly all rebreather instructors have been asked that question at one time or another; and in many cases, more than just one time. Unfortunately, it is an impossible question to answer with anything approaching accuracy or truth, because the question is so ill-defined it is meaningless. One might just as easily ask: “How long is a piece of string?”

If there is a secret to getting a definitive answer, it lies in framing the question within a few well defined parameters.

Rebreather diving is dangerously close to taking on a sort of silver bullet status as the right solution for every type of diving. However, common sense, and a quick summary glance at accident statistics, tells us that it clearly is not.

Running a Closed-Circuit Rebreather is an order of magnitude more complex than throwing a regulator on a scuba cylinder and going for a dive. Dive for dive, operating a CCR safely requires divers to pay attention and develop a skillset way beyond anything required on all but the most complex open circuit dive.

For example, a sure sign that something is wrong with open-circuit life-support is that it stops delivering gas to the diver. This is a graphic indication that some immediate action is called for. A CCR system will continue to deliver gas to the diver but that gas may be totally unsuitable for his current situation and if he is not paying attention, he will continue to breathe until he passes out and dies.

Consequently, the risk-benefit analysis for CCR diving has a very different complexion to a similar analysis for open-circuit diving, tech or otherwise. Short version, there has to be a good reason to choose CCR over OC for any dive; better yet, there should be several good reasons to choose CCR over OC for every dive.

And with this, we arrive at an important waypoint on the way to answering the “is it right for me?” question.

Anyone asking this question needs first to define for themselves what they believe are the advantages of a CCR; what sort of conditions they expect to dive in; and how often they expect to dive. I think as well, they need to look seriously at their dive budget.

Operating cost is one so-called advantage of CCR that gets mentioned time and time again. Specifically that helium costs for deep excursions on CCR are insignificant compared to doing a similar dive on open circuit. For a new CCR diver, this cost benefit can be ignored.

If cost is a person’s main reason for switching from OC to CCR, they are in for a shock and cost should not be a final tipping point in the argument to go with a CCR. Consider first that there is a compelling body of evidence pointing out that for many tens of hours following certification on their unit, regardless of model or type, a diver should revert to tyro-level dives and forego “technical” profiles altogether.

For someone diving as a weekend warrior, this will probably translate into a year or two without seeing a hint of helium in their diluent bottle. (And anyone thinking of taking up CCR diving, especially experienced “technical” divers, should ask themselves if they are honestly willing to accept that “limitation” to their diving? If their answer is no, there is a statistically compelling reason for them to either adjust their thinking or drop CCR diving from their wish list.)

Without doubt, there are dives for which the best tool is a rebreather, but often the pros and cons sort of wash each other out and the final arbiter is personal or team comfort with regards to one or two ‘gray’ issues. I dive a rebreather as a default in but am far from committing 100 percent to it because there are occasions when CCR simply does not make sense.

I guess you could say that my answer to the ubiquitous “is CCR right for me?” question is that it depends.

Douglas Adams, the English writer responsible for The Hitchhiker’s Guide to the Galaxy, wrote: “There is an art to flying. The knack lies in learning how to throw yourself at the ground and miss.” I believe similar logic can be applied to rebreather diving. Sometimes flying is best but occasionally, the bus is a safer option.

Fitness and Flexibility for tech diving

This is an except from my newest book, The Six Skills and Other Discussions, due off-press in mid-February

The most sensible approach for someone considering a move into technical diving is to regard it as physically testing, and respect it as an activity that calls for above average fitness and flexibility. How much above average a technical diver has to be is a debatable point, and the rhetoric runs from the argument that technical divers should be capable of competing in triathlons to a completely hands-off approach that believes any diver is clear to go as long as he can stagger around the dive deck with sufficient control to stub out his cigarette and put down his beer before dropping into the water.

You may, like me, be looking for a set of fitness guidelines that fall somewhere in between those two extremes, and there are several suitable scales to measure personal fitness levels in a way that fits well with the general rigors of tech diving.

The first is the Cooper 12-minute run test. It is used to gauge aerobic endurance, and is perhaps the most straightforward to self-administer. I run a “diagnostic” on myself a couple of times a month and track the results on a spreadsheet. The test simply calls for the subject to warm up and then run as fast as possible for 12 minutes. Results are evaluated on distance covered within those 12 minutes.

A run of more than 2700 metres is excellent, 2300 – 2700 is good, 1900 – 2300 is average, 1500 – 1900 metres is below average and less than 1500 metres is poor. Over the years I have dropped a category but find it has been worth the effort to maintain a rating on the upper end of “good” for several reasons, including resting gas consumption rate.

(The approximate imperial conversions are respectively: more than 1.6 miles is excellent, 1.4 – 1.6 miles is good, 1.2 – 1.4 miles is average, 0.9 – 1.2 miles is below average, and less than 0.9 miles is poor.)

Running speed and endurance are good indicators for tech diving but so too is overall flexibility. There are two methods I use to test flexibility: modified sit and reach, and trunk rotation. Both are part of a whole raft of fitness tests published by the American College of Sports Medicine (ACSM), and I would recommend a visit to their website for additional ideas. Flexibility in the hamstrings and lower back have been an issue with me since childhood and I always find the first of these tests a challenge.

Modified Sit and Reach Test
This gauges the flexibility of the lower back and hamstrings and requires a box about 30cm (12 inches) high and a metre rule:
1. Sit on the floor with your back and head against a wall. Legs should be out straight ahead and knees flat against the floor.
2. Have someone place the box flat against your feet (no shoes). Keeping your back and head against the wall stretch your arms out towards the box.
3. Have someone place the ruler on the box and move the zero end towards your fingertips. When the ruler touches you fingertips you have the zero point and the test can begin.
4. Lean forward slowly as far as possible keeping the fingertips level with each other and the legs flat. Your head and shoulders can come away from the wall now. Do NOT jerk or bounce to reach further.
5. Slowly reach along the length of the ruler three times. On the third attempt reach as far as possible and hold for 2 seconds. Have your training partner read the score. Repeat twice and compare your best score with the table below. (All measurements in cm.)

Gender Excellent Above Average Average Below Average Poor
Male >40 cm 29 – 40 cm 23 – 28 cm 15 – 22 cm <15 cm
Female >43 cm 34 – 43 cm 23 – 33 cm 17 – 22 cm <17 cm

Trunk Rotation Test
This flexibility test measures trunk and shoulder flexibility. The only equipment required is a wall and a piece of chalk or pencil.

1. Mark a vertical line on the wall. Stand with your back to the wall directly in front of the line. You should be about arms length away from the wall with your feet shoulder width apart.

2. Extend your arms out directly in front of you so they are parallel to the floor. Twist your trunk to your right and the touch the wall behind you with your fingertips. Your arms should stay extended and parallel to the floor. You can turn your shoulders, hips and knees as long as your feet don’t move.

3. Mark the position where your fingertips touched the wall. Measure the distance from the line. A point before the line is a negative score and a point after the line is a positive score.

4. Repeat for the left side and take the average of the two scores.

Rating Positive Reach (cm) Positive Reach (inches)
Excellent 20 8
Very Good 15 6
Good 10 4
Fair 5 2
Poor 0 0

Because of the nature of water and the effects of buoyancy, above average strength does not seem to be as critically important for tech divers as it may be for other sportsmen and women. However, some strength building and testing is in order since divers with arms and legs like noodles will be at a distinct disadvantage moving gear from one side of a parking lot to the other, and may find it close to impossible to get themselves and their equipment back onto the boat in a big sea.

The US Marshal Service has a well-respected and openly published set of fitness and flexibility guidelines for the men and women on its staff. These guidelines have been used by some of the tech diving community for years. Some time ago while researching another book, I modified those tables and developed a set of values that seemed to work for most able-bodied course candidates. These values are based on the figures from the US Marshal tables for above average males in each age category.

My personal goal is to stay aged 30 – 39 for the next 15 years.  Some females find regular “military” push-ups difficult and I see no reason why the modified version cannot be used.

Age % body fat Sit and Reach Push-ups Sit-ups 2.4 km run
20-29 5.3 – 9.4 >50 cm >50 >45 < 10 mins
30-39 14 – 17.5 >45 cm >38 >40 <12 mins
40-49 16 – 20 >42 cm >35 >37 <14 mins
50-59 18 – 22 >40 cm >33 >35 <15 mins
60 plus 19 – 23 >38 cm >31 >33 <17 mins

Pre-Order your copy of my new book…

The Six Skills and Other Discussions is scheduled to start shipping February 16, and if you are interested in getting a copy as soon as it comes off press, now’s the time.

You can pre-order from the link below. You do not have to pay anything until your copy is ready to ship and then you will get an electronic invoice. I use paypal and have done for years. If that does not suit, we can work out something I’m sure.

Order Your Copy of Steve’s New Book NOW!

Pre-orders get free shipping in the US and Canada, and to make things fair, UK and European addresses will get a discount on postage. Will know more in a week or so but it looks like postage to the UK will be reduced to about 5 pounds per copy.

Many have asked what the book is about and I tell them it’s full of creative solutions for the puzzles that face tech divers on every dive. But I figured the table of contents would also help. So here it is:


Table of Contents

By Jill Hienerth……………

About this book ……………

Chapter One: Technical Diving and How to Get There From Here
Definition of technical diving and what to expect from a tech diving course……………

Chapter Two: Buoyancy, the force that opposes Gravity
The first of the Six Skills including a novel use for a digital fish scale……………

Chapter Three: Trim, the streamlined approach to diving
A prescription to swim like a fish and get rid of clutter……………

Chapter Four: The Skill of Movement and Position
The last of the physical skills and the guidebook for a four-dimensional game of follow the leader……………

Chapter Five: Breathing, beyond the standard advice not to hold your breath
The first mental skill and elements of gas planning……………

Chapter Six: Situational Awareness, the Chess Master’s skill
Focus, observation, understanding and a touch of clairvoyancy ……………

Chapter Seven: Emotional Control
The sixth and final skill, which is really about a developing a cool outlook and how to maintain it ……………

Chapter Eight: Dive Execution, Equipment Configuration, Doing What Works
Plan your dive, dive your plan and Hogarth ……………

Chapter Nine: The Deco Curve
Contingency decompression made easy. Well, easier ……………

Chapter Ten: Accident Analysis, and chalking the Foul Lines
What goes wrong when people get hurt and how we can learn from those incidents ……………

Chapter Eleven: Parting Shots
Suggested reading, diet, exercise and lateral thinking ……………

Imperial tables and examples for the metrically challenged ……………

Thanks for your attention, folks.

Best wishes for the holidays…

Quite apart from the Holiday and Family time, this is a great time of year for circumspection; how did we do last year, and how can we do better in the coming one?

Usually, I am not big on New Year celebrations, resolutions and the whole ‘New Start’ outlook when a new calendar goes up on the wall. This year is a little different. Early in 2011, I’ll have a new book to peddle. Six Skills and Other Discussions is in layout and final proofing now with a press date of January 24 scheduled. It’s been a long and circuitous journey, but I think it’s been worth the effort and the early reviews from my “editorial board” have been excellent. It feels good to be processing pre-orders and getting ready to sign a few copies (I hope)! Also putting the finishing touches on the training schedule for the Winter and Spring, and looking forward to putting away the snow shoes and getting the rebreather out again, because here in the north, the days are getting longer, which must mean warmer weather is on the way… no?

Best Wishes to all of you regardless of where you find yourselves and Merry Christmas. I will be back in the New Year. Have fun. Dive Safe.

Sign up for my eNewsletter here>>>

A Simple Thought Experiment

Before I leave the whole issue of diver safety and specifically fatalities associated with closed-circuit rebreathers, I’d like to pose a question to you.

I promise to move on to something less somber after this, but please send me your thoughts via comments below or in an email.

Anyway, here’s the scoop.

When it comes to policing who gets to dive a rebreather, every CCR manufacturer seems to use similar tactics. In short, they will not sell a functional CCR unit to John Doe Diver without verification that he has successfully completed a certification program on the unit sometime recently.

If John Diver has purchased the CCR so that he can participate in a course and earn that certification, most manufacturers will either ship his unit directly to the instructor who will be running the course, or will ship the machine to John Diver but missing a vital part (like the scrubber head) rendering it non-functional. The missing part will be sent to the instructor.

This has been common practice for years, and to an extent, prevents untrained, uncertified divers taking their brand-new toy for a potentially disastrous trial run.

So the question is this: What happens if John Diver completes his CCR course and fails?

What if John is so incompetent, so out of sync with the whole concept of CCR diving, that his instructor has to wash him out of the program? In other words, John does not just need a little more coaching; he is so bad in the water on a CCR that it looks likely he may NEVER get it.

The equation is: John plus CCR equals accident.

What does the instructor do with the CCR? Send it back to the manufacturer on behalf of John asking for a refund or does she hold on to it until John tightens up his act and earns a pass sometime in the distant future?

What happens if John signs on with another instructor who teaches to less stringent standards? The original instructor HAS to release the machine at some point doesn’t she? After all, John Diver paid for it. But she believes that the second instructor may turn a blind-eye to John’s poor skills.

Put yourself in John’s place, and his instructor; let me know what you think!

Why so many deaths? What’s the real story behind 18 deaths on rebreathers worldwide so far in 2010?

At the CCR Summit, part of the National Association of Cave Diver’s Conference in Florida early this month, during a presentation on rebreather safety, Jill Heinerth made the statement: “if you own a rebreather for five years, two percent of you are going to die on it.”

Part of the fallout from Jill’s presentation was disbelief and on the various dive and rebreather forums the debate continued for days, and continues as I write this. Hopefully, by poking this issue with a pointed stick, Jill will wake a few of us up to a real and present problem… and also perhaps help to fire-up the right people to work at making a difference.

First off, let’s see if things are as bad as Jill paints them to be.

I’ve worked with statistics and their analysis for a good part of my working career and have a healthy respect and suspicion of them. The stats Jill quoted in her presentation at the CCR Summit were drawn from a paper presented by Simon Mitchell during the Peter Bennett Symposium at Durham in 2005, and then updated and published by Duke University in 2007.

Mitchell, estimated the five year mortality rate for rebreather owners at 0.5 percent based on the number of rebreather fatalities recorded by Diver’s Alert Network (DAN) around the world that year, but warned his data was inconclusive and his estimate “statistically crude”. However, it is a good starting point and to clarify it somewhat, Mitchell confirmed recently that Jill’s figure would fit into the high-end of his paradigm if there were something like 4500 active rebreather divers during a year when 18 deaths were recorded.

One issue with any statistical analysis of CCR risk vs. risk on open circuit or diving generally, is that while we have a pretty good fix on the number of fatalities in a given year, we really have no clue how many rebreathers are out there. Nor do we know how many recreational divers are using them, and we certainly do not know how many rebreather dives are conducted each year (and that would perhaps be the most useful data).

The vast majority of CCR sales are associated with certifications sanctioned by and issued through one of the existing tech agencies. Getting reliable figures from them to cover CCR certs per annum is not easy and would be skewed in any case. For the record, one of the largest tech agencies states that CCR certifications at ALL levels make up less than 2.5 percent of their total numbers. But even interpolating from this figure is difficult because some divers own more than one unit, some certify and then become inactive, some take more than one certification in a given year, and some earn certification on the same unit at the same level with an instructor who issues multiple agency specific certs.

A useful number to work with would be what percentage of total diving related deaths occur on rebreathers in a given year. (The latest number I can lay my hands on is five percent, but with a whopping 18 CCR deaths so far this year, that figure probably will need updating by the end of December.)

What are we left with then? Not much frankly. We do not know how many people dive rebreathers. We do not know how many rebreather dives are made each year. But we do know how many scuba-related deaths there are in a given year, and we know how many occur on CCR.

So we come back to Simon Mitchell’s estimate. If we compare this to the deaths among DAN members over the past few years (1:6000 or 0.016 percent) CCR diving begins to look as though it is more risky than open circuit diving, but even that statement is difficult to corroborate without clearer and more complete data.

All we can really say is that too many people are dying on rebreathers and there must be something we can do about stopping it.

One of the questions Jill was asked at the end of her presentation had to do with the risk factors surrounding fully automatic CCRs and manually operated one. The question essentially asked if it was true that many more deaths occur on automatic machine compared to the manually operated ones.

Jill let me chime in because I dive and teach on a completely manual unit, and as much as I would like to say that manual CCRs are statistically safer, there are no data to prove it one way or the other! Manual, automatic, radial scrubbers, back-mounted lungs, scrubber cartridges or loose kitty-litter, multicolored lights, statistically they’re all the same, and more importantly I believe the problems behind diver accidents, injury and deaths have a common genesis that primarily is only indirectly related to technology.

I disagree with those insiders who suggest that the answer is third-party testing and CE or ISO certification for the machines. I do not buy that HUD (heads up displays), more oxygen sensors, carbon dioxide warning systems, or any other bells and whistles represent a silver bullet that will stop people dying on rebreathers. I think these are all fine concepts and are all worth consideration, but I don’t think they will really help or get to the fundamental problem.

At issue is poor initial instruction, diver complacency and a community ethos that sanctions, or at least ignores, bad habits and sloppy procedures.

I have no idea how much weighting or seriousness to give each of these issues because each is serious and each can lead some poor punter finding himself in a situation that has a better than average chance of a piss-poor outcome.

And sadly there seems to be no easy fix. Industry insiders like Jill Heinerth have been promoting change for years. Perhaps as a community, we can promote and campaign for the good and positive things too.

Here are a couple of pointers that may be of use to you.

If you want to dive a CCR, work with an instructor who understands the value of individual prescriptive training, and who pays particular attention to explaining failure scenarios; and how to work through them. Ask if there is a confined water component to your course. “Pool work” might not be exciting but it can help to build a strong foundation for you as a CCR diver. Find out how the inwater time during your course will be spent, especially the open water dives. The total number of hours is not really an indication of a good course if they are spent sitting in a lotus position looking at fish. Mastering CCR diving takes work and practice, and failure-driven improvements to your awareness and technique.

Ask your instructor for the checklist he uses before his personal dives. If he says he does not use a checklist, run away and find another instructor; seriously. I’ve taken courses with instructors who designed and engineered (and in one case built) the units they were instructing on, and ALL of them without exception, used a checklist before a dive. A checklist can save your life. Use one, always.

Most of all, do not put yourself above your training. All your experience as an open circuit diver is only relevant to diving a CCR after you have bailed out and even then, there are things unique to CCR that you will need to learn and practice if you want to get to the surface intact and whole.

When you first dive a CCR you are a beginner and no matter how good you are on open-circuit, resist the temptation to leapfrog over a training level or two because you believe know all about decompression or trimix or overhead environments.

Finally, take responsibility for your actions. One of my early mentors was W.R. Morgan and his advice was that before you take a shortcut related to any form of high-risk endeavor, from rock climbing to mountain biking, skiing or technical diving, take a piece of paper or index card and divide it into two columns. At the top of one, write “Normal Procedures” and at the top of the other “What I’m going to do instead.“ Now fill both columes in. Take a look at it, sign and date it, now give it to your boyfriend, girlfriend, wife, husband, best mate, favorite waitress, mom or dad, and let them know that if something happens to you, to give it to the folks who will be doing the investigation.

My final thought is this. I dive a CCR because sometimes it is the right tool to do what it is I have to do or what I want to do. All indications are that CCRs present a special level of risk. My training, common sense, and a bunch of procedures and protocols will help keep me safe, and I promise to practice them always.

Now, how about you?

Thanks for your attention.

A word about training: Price vs value (directed at those of you who want to teach for a living)

There is a great scene in the 1994 Quentin Tarantino movie, Pulp Fiction where Mia Wallace (Uma Thurman’s character) orders a $5 milkshake. Business consultant types use Mia’s expensive tastes to illustrate one of the Five Ps that constitute marketing’s basic tenets; in this case Price.

Any self-respecting MBA will tell you that Price is a function of Cost + Value. In other words, the cost of the milkshake’s ingredients has little to do with its price on the menu. The lion’s share of the five dollar price tag is to pay for the value added to the shake by it being served at Jack Rabbit Slim’s trendy themed restaurant. The Jack Rabbit brand is the added value making up the “Price equals Cost plus” equation.

The point is that Mia’s date, Vincent Vega, played by John Travolta, thinks five bucks was a lot to pay for some ice-cream and milk; but he is curious what makes it “worth” the money. When it arrives, he has to take a sip. In Marketing-speak, Vega has suspended his aversion to the sticker price for long enough to “give the brand a chance to hook him.” We might say that the display in the store window has stopped him in his tracks and he has walked into the shop. Vega has become a potential customer of the $5 shake, and is ready to be “sold” or more precisely, closed.

You may or you may not be a fan of Tarantino, milk shakes, and Uma Thurman, but the odds are that you “own” a brand. The smart bet is that you fit into the model that describes the majority of consumers, and there is something you buy regardless of its price because you value the brand – Lacoste polo shirts, Guicci fashion, Louis Vuitton luggage, Christian Louboutin shoes and bags, Roger & Gallet soap, Rolex watches, the list goes on, and it includes a whole raft of everyday products and services, not just the luxury brands.

In the business of marketing, which is business pure and simple, selling brand awareness and ownership to the target consumer is issue number one. Discovering what price the market will bear for that brand comes a close second; and is driven in part by a deep belief that quality has a bearing on price. High price equals real value; discount price equals low value. “Starbucks coffee really is worth the extra few dollars because it is so much better!” True or False?

Now let’s change gears entirely; let’s apply what we have learned from Tarantino’s milkshake, and a double, skinny latte to buying technical diver education. Specifically, let’s break down cost and value of a technical program to explain price.

Take my situation as an example. Let’s say that I need to build a new business plan and my financial “guy” – a true eccentric with credentials in law and forensic accounting – has asked to see a detailed breakdown of an “average” course. Because of his background, and because I have known him since the era of the “Blondie is a Group” button campaign, bullshit is totally not an option.

To work then.

The cost of materials and the cost of delivering a day of training per student can be worked out with the help of last year’s stats, some informed estimation, and careful scrutiny of all the things it takes to maintain active status as a technical instructor. This includes all the normal cost of business items needed to run a diver training facility from insurance and paperclips, to $2400 drysuits and vehicle maintenance.

I prefer to have this figure worked out to give a dollar figure per student per day. This means that if a program takes one day or ten, ballparking a cost is simple multiplication. Working this way does mean that my business plan projects similar per day costs for a simple intro to tech class conducted at a maximum depth of about 20 metres and a much more complex advanced trimix class held in 100 metres of water, which skews some of the fixed costs. But that’s OK. Accordingly, we will say this number is X dollars per student per day.

So that’s cost, now how about the added value; what do I add to a course that justifies me charging more than a straight $X a day, 4 x $X for a four-day program?

Because teaching is what I do, the value component is important to my survival and has to supply me a living wage; a profit. But is that an added value for my customers? I don’t think so. In fact it has nothing to do with it unless I market my classes as a sort of Support Steve Lewis’ Lifestyle Program. And I do not think that will work too well.

But if that is not the value, then what is? Perhaps this is where another P of marketing should be brought into play; what exactly is the product or service that I sell… that YOU will sell?

Well, we could itemize a whole list of things, time, security, adventure, empathy, a slightly off-kilter perspective, a scientific mindset, bad knees, green thumbs, etc. But it really boils down to experience. I have accumulated a lot of experience diving and teaching. By the time you start to teach technical programs, my hope is that you too will have a store of experience to dive into when faced with the eager faces of a class filled with students ready and willing to have you take them to some god-awful depth in the back of a decaying hunk of steel and wood surrounded by water moving at a couple of knots.

Perhaps also important on the Richter Scale of earth moving experiences is that you are still interested in building your personal experience. Simply put, this translates as: Dive for fun and occasionally, do something that shakes you out of complacency. A really well-known instructor I know says that part her value statement is that she is always scared.

So what’s all that worth I wonder? That stuff is the added value! All I have to do to satisfy the new business plan is to put a per-day cost on all that and fire it off to Mr. Bean Counter. So how much? Does $Y sound about right?

I like good pottery. In particular, I love simple pottery bowls.

Perhaps I like them because I have tried to make a pot and with authority can tell you that I am the second worst potter alive in the world today. In any event, I appreciate the space a good bowl takes up, and knowing this someone told me a story one time about a famous Japanese Zen potter who was being interviewed by a writer from a big circulation American magazine. As the journalist was asking questions, snapping photographs and taking notes, the potter continued to turn his treadle and throw pots. During the course of the interview, three or four dozen perfectly formed bowls took shape on the potter’s work bench.

With the interview drawing to a close, the writer asked how much one of the bowls would cost. “About four or five hundred dollars,” said the potter. “Holy shit,” the journalist said, rather undiplomatically. “Five hundred bucks and they take you about 30 seconds a piece? Wow!” The potter laughed and said, “well, that’s not exactly true.” He picked up another ball of clay and threw it exactly onto the center of the spinning wheel. “Today is my birthday and I am 77 years old. So this pot I am making now took me 77 years AND 30 seconds to make!” He looked at the journalist and smiled. “How long does it take you to make 500 dollars?”

No, thinking about it, perhaps $Y is not enough.

Accident Analysis

Dialogue One (A rejected chapter from The Six Skills, Decompression Curve and Other Discussions)

Chalking the Foul Lines: Dying because of recklessness does not constitute an accident.
Based on a dive safety presentation first delivered 1999

“Too often the shortcut, the line of least resistance, is responsible for evanescent and unsatisfactory success.” Rabbi Louis Binstock (1896-1974)

The Niagara Escarpment is the limestone-capped rim of a huge bedrock bowl running west and north from Rochester, in up-state New York, through the Canadian province of Ontario, across the top of Lake Huron and then curving back into Michigan, Wisconsin and Illinois. On its way from the southern shores of one Great Lake to frame the western shore of another, it forms the cliffs of Niagara Falls, dissects Ontario’s wine county and forms the tree-covered spine of the Bruce Peninsula.

The escarpment submerges there, at the end of the Bruce Peninsula, and for about 50 kilometers, until it surfaces at Manitoulin Island to continue its arc back through the United States, there is a navigable waterway connecting the main body of Lake Huron with the expansive waters and approximately 30,000 islands that constitute Georgian Bay. This waterway is part of the network of commercial shipping lanes that opened North America to European settlers, but more important to divers, thousands of ships, from simple gaff-rigged fishing boats to gigantic steel freighters passed through there, many of them meeting their end in the process.

At the southern end of this gap at the very tip of “The Bruce” is a small fishing village called Tobermory. On Highway 6 just at the edge of town is a sign welcoming visitors to “The Scuba Diving Capital of Canada.” While the local chamber of commerce may be guilty of optimistic overstatement, the clear, cold water off Tobermory, and Fathom Five National Underwater Park, attracts divers to the area by the boatload in the summer and fall. It’s a rite of passage for sport divers from southern Ontario and neighboring American states to make the long trek north to dive on one of twenty or so shipwrecks broken and torn apart on the sharp rocks that ring that coast.

In many spots along the coast of the Bruce, vertical dolomite cliffs take an almost vertical plunge 100 metres or more beneath the waves. Outside the boundary of the national park, there are also a few wrecks far too deep for sport divers but appealing enough to bring technical divers to the village in great numbers. Oddly enough, these deep and somewhat remote dive sites account for very few diver fatalities. The bête noir in this area is a small wooden barque sunk within sport diving’s limits, and a twenty-minute boat ride from Tobermory’s Big Tub Harbor.

Since the discovery of the sailing vessel Arabia in the early 1970s, more than 14 divers have perished on her. Far more than any other wreck in the Province of Ontario and perhaps any single spot in Canada and the USA, including any individual Florida cave or the fabled wreck of the Andria Doria off America’s Atlantic coast.
Every dive season there are countless near misses on this little wreck as well. Divers make ballistic ascents. They lose contact with their dive buddy and panic. They forget to make required safety stops. They get lost, run low on air, and make mistakes that could snuff out their lives and add to the grim statistic that has earned the Arabia the somewhat sexist nickname “The Widow Maker.”

The real challenge is explaining why a rather ordinary wreck sitting in a fairly sheltered spot, with moderate visibility and light current, is so dangerous. Based on the records of diver deaths in this region, deeper dive sites protected by tougher environmental conditions and offering many more opportunities for grief are comparatively benign.

One guess is that too many people are looking for a shortcut and the Arabia is an assessable “challenge” visited by a number of suitably-equipped charter boats and therefore readily available to wreck divers, even those capable of faking a logbook and embellishing their experience. Without doubt the unfortunate history of the wreck exudes a kind of morbid attraction to this last category of fools.

We live in a society promising magic pills to make us fitter, thinner, younger, more attractive, and smarter: so much so that the expression “paying one’s dues” and all it suggests is considered out of touch. Subscribing to a philosophy that promotes earning privilege by hard-won experience and the slow accumulation of skill is considered “old school” and unfashionable.

The diving community certainly has members who are looking for shortcuts to “class dive sites” without prerequisite experience and skill. However, diving is not a pastime for shortcuts, and the Arabia was the stage for one incident that confirmed this dictum with blinding clarity.

One summer’s day a few years ago, a young man, who we’ll call Bob, decided to pay the wreck of Arabia a visit. Bob had just finished his open water scuba diver certification and the site was not one he had any business visiting. Apparently some friends warned him about attempting the dive, but according to later accounts, he was resistant to the meaning of caution. The site’s reputation as a potentially dangerous one was said to be a huge part of the lure. Bob had visions of diving all the well-known wrecks off the North East coast the following year and this adventure on Arabia was to be a warm-up.

Arabia sits broken but essentially upright in about 32 metres of water… approximately twice the depth Bob’s freshly minted open water card certified him to dive. Outfitted in rental dive gear he unfortunately found a boat willing to take him to the site. Since his was going to be a deep dive, and he’d heard that decompression gas was a good idea on deep dives, Bob strapped a stage bottle of nitrox to himself — a gas he was not certified to use — and, diving alone without the help and support of a buddy, went exploring.
We will never know what he saw or learned on his dive because Bob was found a couple of days later lying on the lake bottom less than a hundred metres from the wreck, long dead.

As truly extraordinary the symmetry of its stupidity, and as sad its outcome, this was not a particularly unique or isolated incident. Another death around the same period, involving an equally inexperienced diver on the Forest City, a deeper more challenging wreck in the same area, illustrates that. Every year there is a miserable list of equally dreadful cases where over-confidence, poor judgment and ill-informed choices result in the thinning of the herd.

And we should remember that such acts of folly are not restricted to beginners. Highly experienced divers seriously injure themselves and sometimes die too.

Jennifer Hunt, in a study published in Psychoanalytical Quarterly in 1996, focused on “Sam,” a pseudonym for a well-know New Jersey wreck diver and author. Her article, entitled Diving the wreck: risk and injury in sport scuba diving, explored Sam’s motivations for continuing to conduct technical dives following a near fatal accident. Sam had suffered a very serious decompression episode the year prior to her interviews with him — an incident he documented as a sidebar in a best-selling book written later. Disregarding the physical injuries caused by the incident, he continued to engage in deep wreck diving in a high-risk environment ignoring medical advice not to.

Hunt draws an interesting and somewhat disturbing picture of how unresolved psychological conflicts may influence a person’s approach to diving. She also teased out of many months of research an explanation of what compels divers to ignore evident risk.

“Like Sam,” she wrote, “a number of deep divers appear to link masculinity to involvement in high-risk activity. This unconscious link between risk-taking and masculinity is given cultural support within the deep diving community.”

I know Sam well enough to believe Hunt’s assessment of him is off the mark. After conversations with him, I read his motivations as having little if anything to do with perceptions of masculinity or influences drawn from his peer group. Sam’s decompression blunder was no accident but the direct result of carelessness and oversight. Sam’s actions were not driven by testosterone-soaked myopia, but a different flavor of foolishness — complacency of the experienced.

I think Hunt drew the wrong conclusion about Sam but I do not think she is wrong in all cases. Certainly her reasoning explains why some divers – experienced and inexperienced – attempt things outside the purview of their personal limits; even when they have full knowledge that what they intend to do is risky.

Some misguided link between “being a man” and taking foolish risks certainly helps to account for the behavior that resulted in Bob’s death on Arabia… but what else is there and what steps can each of us take to manage and control our own behavior in order to lessen the chances of suffering a similar fate? Step one is to identify and then avoid things that cause serious dive accidents.

The simplest way to stay out of the statistics column is to have a realistic grasp of your personal limits and the limits of your gear and then to stay well within those limits. It’s that simple; however, most of us need some help being honest and well-informed about where our limits actually lie.

Cave diving remains the purest form of high-profile, complicated diving. It’s also the branch of diving that offered the original properly organized training and certification for what we now call technical divers. The first recorded scuba dive into a cave in the USA was conducted by National Speleological Society divers in 1948, and the Florida chapter of that organization held the first cave training sessions for divers five years later in 1953. By the late sixties and early seventies, cave diving was being taught actively in North Florida by two groups, the NACD (National Association for Cave Diving) and the NSS-CDS (National Speleological Society – Cave Diving Section).

Cave diving, as with any form of extreme sports, carries considerable additional risk on top of the list of commonplace ones attached to the ordinary, everyday version of the sport… in this case, open water scuba diving. As the popularity of cave diving grew, so too did the number of diver fatalities in Florida’s caves. Pretty soon, cave training programs included modules on Accident Analysis, during which students and their instructors, in an attempt to avoid a similar fate, engaged in detailed discussions about divers going into caves and dying in there.

This “accident analysis” segment of diver training was radical stuff… a complete departure from the candy-coated puff being delivered to the mainstream dive-industry customer.
In his seminal writings on dive safety, Basic Cave Diving: A Blueprint for Survival, Sheck Exley was among the first to identify that most fatal and near fatal incidents in caves are the result of people ignoring one or more of the five safety procedures. Exley, pioneer cave diver and explorer, originally recorded these five principles or best practices as: Training; Guideline; Gas; Depth; Lights. (A mnemonic to remember them is Thank God, Good Divers Live.) This translates into: Do not exceed or ignore the limits of your training (and experience by implication); Always maintain a continuous guideline to open water / the surface; Plan dives around adequate gas volumes and oxygen partial pressure; Stay within the working depths of your equipment, your level of concentration, nitrogen partial pressure, and comfort zone; Carry backup lights to preserve safety and comfort in the event of primary light failure.

In a 1992 article in Aquacorps Journal, Michael Menduno, the magazine‘s founder and editor-in-chief, used Exley’s accident analysis technique to pick apart eight diver deaths that had occurred in the United States dive community inside a 12-month period. The fatal sites were a mix of caves and deep wrecks and one deep open-water location.

At Alachua Sink, considered an advanced Florida cave dive, a newly certified cave diver became lost in the cavern zone and drowned. An experienced cave diver suffered a CNS (Central Nervous System) oxygen toxicity episode diving Devils Eye, also in Florida. The wreck of the Andrea Doria claimed two lives in separate incidents; one diver simply ran out of air, the other became lost inside the wreck‘s maze of cabins and companionways. On the Arundo, a wreck off New Jersey, a diver experienced an oxygen toxicity event and died. The Chester Polling, off Massachusetts, claimed the life of an experienced wreck diver conducting a dive to 52 metres (170 feet) on air. And two buddies attempting a 75 metre air dive (250 foot) wearing only single 11 litre cylinders (aluminum 80s) and with only sport-diving gear and training, died in La Jolla Canyon, off California‘s southern coast.

Menduno, who is credited with coining the term technical diving, wrote “Unfortunately in most of these cases, experienced divers violated one or more basic safety principles and died as a result.”

He went on to explain “the predominant causal factor was the lack of a “continuous guideline” (line system) to the surface that serves as a critical navigation device in the overhead environment of a cave or wreck and an important staging tool during open water staged decompression. Even in the absence of rough sea conditions executing a five to ten stage open water hang in the absence of a decompression line is hazardous and tricky particularly when using hyperoxic mixtures for decompression where depth control is critical.”

He identified that the second most predominant factor in the 1992 deaths was “inadequate gas management,” and stated that in the instance of one Andrea Doria incident and the ridiculous depth attempt at La Jolla, divers entered the water with insufficient gas to conduct the dive safely and handle an emergency.

“They were,” Menduno wrote. “In effect conducting suicide missions.”
A couple of months following the publication of Menduno’s article, and ironically during a workshop on diver safety that boasted a panel made up of many of the top advanced divers and dive-trainers of the period, came news of deaths nine and ten: those of Chris Rouse Senior and his son Chris Rouse Junior on the wreck of the U-Who, later identified as the U869.

Exley’s ideas had gained general acceptance and had stood for several years unchanged and unchallenged but shortly before his own tragic death in April of 1994, exploring a deep cave in Mexico, Exley revisited his work on accident analysis and expanded his safety procedures to reflect massive changes in the world of technical diving and to accommodate the widening appeal of technical diving with divers outside a cave environment. In addition, a veritable who’s who of advanced diving adding their input and suggestions to Exley’s framework, and the results now, almost a generation later, is a Risk Management Process intended to help prevent unnecessary deaths, and to help drive home to a growing audience of enthusiastic divers, all ready and willing to push the envelope, that while technical diving is fun, it is totally unforgiving of the foolhardy.

Risk Management is the identification, classification, avoidance and mitigation of risk. In order for it to work, it requires honest and detailed answers to some straightforward questions and following some common-sense guidelines organized into eight categories: Attitude, Knowledge, Training, Gas Supply, Gas Mix, Exposure (the combination of Decompression and Depth), Equipment, and Operations… let’s take a look at them.

The fundamentals of diver safety really all boil down to attitude. If we pick through the cascade of events that led to a diver’s death or serious injury we find common mistakes and rash decisions were the catalyst for disaster. In the majority of cases, these events began and decisions where made before the dive took place and were the result of recklessness (Sam’s example) or machismo (Bob’s example). Before every dive, a technical diver should ask themselves this question: “Why am I doing this?”

There is no room for a cavalier attitude. There is no time for bullshit. And technical diving is no place for people trying to prove their manhood. If you recognize these traits in your attitude, take up golf and stay the hell away from technical diving.

Mark Twain said that it ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so. That’s pretty succinct, because most of the targets in diving are moving rather than stationary, and there’s more alchemy than science to it. And so it follows: No dogma; No absolutes; Only an open mind.

Knowledge is also understanding that you need to have options when things don’t turn out the way you expected. And wisdom is having the insight to choose the option most appropriate for whatever the current circumstances may be.

Both knowledge and wisdom also contribute to the technical diver’s mindset, which accepts that there is always more to learn and often a better way to accomplish one‘s goals.

Stay within the limits of your training and you will weight the odds in favor of survival; exceed or ignore your training and the odds very rapidly swing in the opposite direction.

Scuba diving is a pastime built on and driven by training. It starts with certification as an basic open-water diver and progresses from there. Technical training is an ongoing process and never stops. A diver never “has enough” training. In this regard the situation is similar to training for an athletic event.

Graduation from a formal course is a good first step, but it is only a first step and carries no guarantee that a diver is prepared to make a specific dive. There’s more to technical diving than holding a c-card. One key element in a diver’s development is practice. Well-directed and well-accessed practice builds muscle memory, familiarity and competence… it is what prepares a diver for a particular dive.

Experience is the other key component. Exposure to specific environmental conditions is the only preparation that counts towards preparing for dives in that environment. For example, extensive wreck diving experience does not qualify a diver for cave diving and visa-versa

Even the most cursory glance at the growing list of dive “accidents” tells us that any recreational dive can morph into a nasty situations when someone attempts a dive they are not trained to do in an environment that is unfamiliar to them. A workable analogy would be attempting Parkour off a three-storey balcony to see if the sport’s to your fancy. Either option is going to land you in the emergency department.

In a cave this simply means that a dive team must maintain a continuous guideline to open water: think Ariadne, Theseus, the Minotaur, a ball of string and the Labyrinth. Explored caves — that’s to say the vast majority of caves visited by recreational divers — have a network of permanent lines in their passageways. These guidelines are placed strategically throughout the cave’s main tunnels and branch lines. At regular intervals, markers — usually plastic, but metal or tape in rarer cases — are attached and indicate the distance to and direction of the nearest exit. Cave divers also carry reels of line with them to gap any breaks in the permanent lines — intentional or otherwise. By following this rule, a cave diver always knows where he and his team is in relation to open water and fresh air. ‘Loosing the line’ or not having one to start with, has been a contributing factor in many, many cave fatalities.

The same guideline rule holds true for wreck divers penetrating wrecks, with the difference that wrecks seldom have fixed permanent lines so wreck divers install as they go and retrieve as they exit. But the comfort and security of a continuous guideline out of the overhead is paramount.

In an open water, non-overhead environment, ‘Guideline’ can be translated to mean three things: the first always having a bearing on the preferred exit — such as a friendly shoreline or boat — which is a case of knowing where to surface rather than where the surface is.

Secondly, it is knowing where the team is at any moment in relation to the planned route, including entry and exit points. Since there is no actual line and no specific markers with distances to the exit written on them, this exercise can be more complex in open water than in a cave, because there is no easy or apparent ‘map’ to follow. However, natural navigation and noting distinct landmarks helps immensely.

Lastly, complex decompressions in open water are made less stressful, and more controlled, with the simple addition of an ascent line. This can be fixed in place and have contingency gases staged at various points in the water column. It can be a DSMB (Delayed Surface Marker Buoy) deployed by individual divers or by the team, or it can be a full-blown decompression staging platform complete with contingency gases, surface supplied oxygen, refreshments and piped music.

Getting lost in a cave is usually fatal. Getting lost on a dive in the open ocean, on a wreck or otherwise, can be equally serious. Currents, big seas and fog can make surfacing at the wrong end of a 120 metre wreck more than embarrassing. The simple and most supportable solution is to use an upline.

There are lots of bad things that can happen underwater but the worst thing of all is running out of something to breathe. Where there is no direct access to the surface — such as in a cave or when there is a decompression obligation — this is a total show-stopper.

It follows then that technical divers make sure there is a sufficient volume of gas for everyone to get back to the surface, and there is some redundancy built into each diver‘s gas delivery equipment. For this, they use techniques originally developed by cave divers.

In its simplest, unmodified form, The Rule of Thirds (one third of the staring volume for entry, one third for exit, and one third for contingencies) is a bare minimum approach to gas volume management, and not by default the best option in a hard overhead environment. For example, if a cave diver looses back gas just as he and his buddy reach thirds — the worst-case scenario — they will most likely not make it out of the cave, but will exhaust their gas supply within a short distance of the cave entrance. The logic here being that the journey out will require slightly more gas than the journey in on account of several factors, such as one or both divers being stressed — breathing harder — the journey taking longer since both divers are tethered by a long hose, and silt-outs are a distinct possibility with one or both divers distracted by the stress of sharing gas for a longish swim.

But the rule of thirds is a fine starting point to plan from. In essence, there should be sufficient reserves for the dive team to exit safely in the event one diver suffers a catastrophic gas loss. In open water this means the plan should include contingencies for all the team to reach the first gas switch with a comfortable cushion. Generally, this is accomplished by the team’s penetration or bottom time being governed by the gas volume of the team member carrying the least number of litres or cubic feet. This volume is used in gas supply calculations.

The situation with decompression gas is similar in that contingency volume must be planned for. The consensus seems to be that each team member carries sufficient deco gas to allow two divers to complete the optimal decompression schedule.

Except in exceptional circumstances, an open-water technical diver must carry all the gas he will need for the dive. Unlike his cave-diving buddy, there are few options for reliably staging primary gases in open water.
Having gas and not being able to access it accomplishes nothing as so in addition to gas volume management, technical divers dive with a gear configuration that provides a backup gas delivery system. In the open circuit arena this may be a set of doubles with two first stages, a stage bottle of bottom gas with its own regulator, or a sidemount rig. When diving a rebreather, this means carrying an independent bailout cylinder with its own regulator.

The next to worst thing that can happen to underwater is only having something inappropriate to breathe or breathing a gas that is ‘toxic’ at depth. For example, breathing a mix delivering an oxygen partial pressure higher than convention dictates… which is a maximum of 1.6 bar. This also covers breathing mixes that have high narcotic loading, are hypoxic — deliver a low oxygen partial pressure — or — in exceptional exposures — mixes that may encourage counter diffusion issues.

The rule is to always dive the safest possible mix(es) for the planned dive; always analyze and label gas before making the dive. Above all, make sure that you know what you are breathing and that you are sure of its Maximum and Minimum Operating Depth(s).

Clear labels stating MOD should be visible on both sides of any stage bottles taken into the water. Permanent labels and touch identification on regulators for conditions of zero visibility are all well and good but are secondary to clear markings based on analyzed contents.

Keep oxygen partial pressures lower than 1.4 bar for the working phase of a dive. On deeper dives, knock this back to 1.3 or 1.2 bar. During decompression, increasing oxygen levels to a maximum of 1.6 bar must be done with care and attention to stay within 80 percent of NOAA’s oxygen single exposure limits. In the event of multiple dives over multiple days, track daily/24-hour limits as suggested by NOAA. Do not exceed them. There have been several ‘unexplained’ CNS toxicity incidents that seem to point to issues with these particular limits.

Keep nitrogen partial pressures within supportable limits. Personal comfort zones may vary depending on the type of dive and environment, but 3.1 to 3.5 bar is becoming a standard acceptable narcotic dose.

Decompression Sickness (DCS) is a predictable sidebar to all forms of scuba diving. The potential for risk of DCS is greatly increased during the sort of deep and long dives typical of technical exposures. Prudent technical divers always use proven decompression methods and the most up-to-date tools for dive planning. They dive conservatively and make ample allowance in their ascent schedules for working dives, dives in cold water, exceptionally deep dives and dives using helium. They carry tables for lost gas contingencies, and use hyperoxic mixes (either nitrox or high-oxygen content trimix) for decompression, never bottom gas, and optimize their final stops (at 6 and 3 metres) by breathing pure oxygen or something close to it. Air is an inefficient decompression gas and has a poor record at reducing decompression risk (Vann, 1992), so they avoid its use in all but the most extreme circumstances.

Another good practice many adopt is keeping detailed notes of decompression schedules and their ‘health’ after their dive compared to the way they felt before the dive. They refer to these notes when planning future dives.

Thanks to decompression planning software, personal dive computers actually intended for use during staged decompression, and a growing data set cataloging successful dives in the top-end range of 75 metres (about 250 feet), the number of serious decompression incidents among technical divers at these depths is surprisingly low… far from totally acceptable but nevertheless the risk is tolerable to many weekend divers. However, technical divers have to accept that dives deeper than 100 metres (about 330 feet) seem to engage a whole new level of vulnerability to DCS, which puts dives to these depths beyond the scope of all but the most careful of divers, and those who have planned dives with the additional security of in-water and surface support.

In conditions where there are strong or variable currents, cold water and the possibility of limited visibility above or below the surface — when wreck diving for example — bottom times should be kept as short as practical to ensure that total in-water exposures do not add factors such as thermal stress and the possibility of losing contact with the surface support to the risk .

Better expressed as Personal Depth Limits, this rule primarily reminds divers to factor into their plans the effects of narcosis, and a variety of other issues that negatively effect their personal performance.
To the majority of experienced divers, deep is a relative term, and one used with some caution. For example, deep in cold, murky water with strong currents begins when the reading on a depth gauge is much shallower than it does in warm, clear, calm water. A very well-known cave explorer says that deep is any water he cannot stand up in and breathe fresh air. Deep can actually be shallow, it just depends.

The same can be said for the Count Dracula of tech diving — narcosis — because it too is a relative term.
The biophysics of inert gas or nitrogen narcosis are pretty much solid state. The actual changes made to the nervous system would suggest a constant effect that while not completely understood would most likely be linear. But narcosis is wildly variable and its effects oddly unpredictable. The function of partial pressure — expressed in bar and increasing at a steady rate as a diver sinks further beneath the surface — does not account fully for the dramatic variations in the risk and severity of narcosis that divers experience. The only logical explanation is that factors aside from nitrogen partial pressure play an important role in narcotic loading. These factors certainly include stressors such as cold, poor visibility, carbon dioxide retention, mental stress, task-loading, tiredness and poor cardiovascular fitness. All these exacerbate narcosis and work independent of depth. Helium is the crucifix and garlic necklace that can combat narcosis, but thinking it alone makes deep diving ‘safe’ simplifies a complex issue and trivializes other important factors.

One factor that is a real concern for ’deep’ diving is concentration… by which is meant being focused on the task at hand. Of course concentration can be negatively affected by narcosis but if there is little attention paid to being focused to begin with, the situation can get out of hand quickly. One can regularly see divers who have plenty of helium in their mix, but who are as incapacitated as the regulars at a Grateful Dead concert as soon as their heads disappear under the water.

Being unfocused and letting one‘s concentration drift around like a ten-year old in Hamleys Toy Shop seems to signal every venerable piece of kit to loosen, break or fall off… or so it seems. The poor diver is brought back from his reverie to find the first stage of his deco regulator floating off into the abyss or something even worse.

Concentration, like buoyancy control and a reverse frog kick, is a learned skill and can be worked on… should be worked on just like any other. Car racers are big on concentration because of the importance of being focused as you approach a 90-degree corner at killing speeds. Their rule is that an additional 10 miles per hour requires 20 percent more concentration. That’s not a bad rule for divers: 10 feet 20 percent more focus.

Under Exley’s original safety guidelines aimed at someone diving in a cave, light was an essential. Without light, finding the way out would be a serious challenge. Because of this, cave divers each carry one primary light and two backups. A dive is aborted if a primary light fails.

Within the expanded guidelines, lights is code for equipment: specifically having the right gear for the job and appropriate backup.

A diver’s equipment is his life support system. It should be treated with respect. Most divers who want to avoid surprises, have gear serviced at least as often as recommended by its manufacturer, and inspect their dive gear before every dive, paying particular attention to hoses and Orings. All regulators, lights, and subsystems such as spools and surface signaling devices should be tested before the start of every dive.
In technical diving, there are no accessories. If a piece of kit is carried into the water, it’s because it is an essential tool for the dive, so it must be inspected and tested. Everything that’s essential should be backed up: either carried by the diver himself or as part of his buddy’s kit.

The primary mission of all technical dives is that every member of the team finishes the dive in no worse shape than when they started it, and so it follow that safety is always the first priority.
The most successful technical divers look at their dives as complex entities that require some considerable degree of organization that includes, planning, preparation, the correct equipment choices, teamwork, efficient execution, and the capacity for any and all team members to respond to any emergency effectively and immediately.

Above all, technical diving is a team activity. The buddy system works OK for sport diving, but technical diving often goes more smoothly with a team of three or more. A team extends to those left on the surface, which includes, in the case of boat diving, a minimum of the captain and crew. For complex dives, support divers may be required as well as additional surface personnel. Communications within this group at all phases of the dive is vital. Often, complex dives require an operations manager or a ‘diving officer.’ This person oversees diver safety, sees that protocols and procedures are followed, keeps records and, in the event of a mishap, takes charge of the response.

At no time should any diver be pressured to attempt to dive outside their “comfort zone,” and each diver carries the responsibility for their own safety. Because of this, the cardinal rule of all technical dive operations is that anyone can call a dive for any reason without fear.

Fatal dive accidents frequently have multiple and complex, often interconnected, root causes. While each accident has unique qualities about it – in part because of the individuals involved – most accidents can be characterized as a chain of events that lead to disaster.

This chain of events very often starts with a minor challenge… a failure in communications, a broken strap. But like dominoes, one event triggers something more serious, and this in turn results in more escalating calamities until all the dominoes have all fallen down. Technical divers need to get pretty slick at removing a domino early on and breaking the chain. Often something as simple as calling a dive early, before anyone gets close to the edge, can change the outcome radically and turn a nasty epiphany into a positive learning experience.

Unfortunately, the more challenging the dive and the greater the distance between it and mainstream sport-diving limits, the more risk is involved. This is the price we have to pay to experience something out of the ordinary and truly exceptional. No amount of training, experience, equipment or good luck will completely mitigate this risk, and sometime sooner or later, many of us will get our fingers burned. We do well to remind ourselves often that if we participate in technical diving, there is always a risk of serious injury or death.

Wes Skiles

“Mourning is not the end of the relationship. We meet their absence everywhere.” Old Jewish Proverb.

Sometime yesterday afternoon, our community lost a brilliantly gifted member. Wes Skiles, whose underwater images (still and moving) are among the most captivating and vocal, passed away while working off the coast of Florida.

Wes Skiles was totally committed to his art, and his family and friends, and he will be missed… immensely.

A good memory: sitting in the living room at Lacey’s Inn in North Florida listening to Wes explain his first dive in a Newt-Suit and the sensation of having a six-gill shark swim between his legs. Funny. Thought-provoking. Nuts.

Perhaps the best way to say thanks is to pass along his love of adventure and respect for the world he helped to make a better place.

Nat. Geo Blog

Teaching an old(ish) dog, new tricks

A really good friend of mine who runs a charter boat out of Florida has a wonderful phrase to describe divers  who are really set in their ways and somewhat complacent when it comes to dive prep. You may have seen them on a dive boat near you. They always dive exactly the same gear package, right down to the back-up lights on their shoulder harness, double cylinders, a stage bottle, canister light and a full complement of reels, spools, and sundry accessories; including a scooter.  Now he is first to admit there’s nothing inherently wrong-headed about that, except they dress the same regardless of whether the day’s target is a 150 foot dive on a brand-new wreck or a 25 foot bimble in a local quarry.

He calls them One-Dimensional Divers.

“I think they are so blinkered and taken with the self-importance of being a technical diver,” he says. “They forget to stop, smell the roses, and kick back!” He says that the real sign of a one-dimensional diver is that they can turn the simplest of dives into a major undertaking. “And where is the fun it that?” he asks.

And after 18 years of lugging a full North Florida Cave Diver’s rig around the country, and using it on even the most straight-forward dives, I felt I’d fallen into the one-dimensional mode myself. I told my buddy things had to change; and he offered the perfect solution. “Buy a closed-circuit rebreather.”

Working for a training agency gives an old guy like me a slightly off-kilter prospective on dive gear, dive travel, and the whole business of diver education. For example I figured I knew quite a bit about CCRs (closed-circuit rebreathers) because I have an instructor rating on a SCR (Semi-Closed Rebreather), have proofed rebreather manuals, and have logged lots of hours on several different CCR units doing everything from try-dives to bona-fide courses.

How wrong I was.

The seed change was actually getting a unit of my very own to look after. Not a loner, not one that a manufacturer suggested I take a look at, but one that I had to take apart, clean, keep spiders from visiting, change its do-dads from time to time, reassemble, and learn to dive from ground zero with the express goal of getting comfortable enough on it to drag it halfway around the world to dive the wrecks of Truk Lagoon.

To be blunt, it was one of the best things that has happened to me and my diving in a long while; and it certainly has also been among the most instructive.

The reasons for this are varied and many faceted but let’s keep things brief and simple and start with the whole one-dimensional / complacency thing. No matter how hard one works at keeping focused and realistic about skills, planning, only taking into the water what’s needed on the dive, and doing things to the letter, human nature has a wonderful way of turning short-cuts into “best practice.”

On open-circuit dives, it is very easy for an experienced diver to become one-dimensional. So much so that at times, dive plans for commonly done personal dives – ones that fall into the “I have done this a thousand times before” category – became marginally adequate at best. As little as it turns out I know about CCRs, I did know enough to understand that the one-dimensional / complacent approach will quickly get you in a very deep pile of trouble.

Occasionally doing something totally outside the norm, helps adjust one’s attitude. Training on and then diving a piece of kit that resembles nothing you are used to diving, definitely turns a few knobs.

As you know, a rebreather recycles exhaled gas, scrubs out the carbon dioxide, squirts a little oxygen back into the mix to compensate for the stuff used by the diver’s metabolism, and is designed to keep the process going for hours at a time. It also mixes gas so the diver breathes “best mix” regardless of depth and it does all this in a compact package (read this to mean, less weight than a set of doubles!).

The other side of the coin turns up the nasty little vagaries attached to rebreather diving, and understanding and working around these is the central theme of a rebreather class.

In short, a CCR can deliver too much oxygen one minute and not enough the next; both harbingers of a bad day at the office for any diver. The little chemistry set that extracts carbon dioxide from the breathing gas can suddenly stop working for all sorts of reasons; most attributable to user error, and again bad news all round. The unit can leak a little making breathing an awful chore, or it can leak a lot, flood and cease working at all; both of which are good reasons to bailout and go home with one’s tail between one’s legs.

All this of course comes as a real eye-opener to the experienced open-circuit diver who has been diving the same kit configuration since Reagan was in the White House.

My other eye was opened by our CCR instructor, a good friend who for that reason alone cut me and my buddies zero slack during the whole week we worked with him to earn our certs on the Pelagian manual CCR we had opted to buy.  He pushed us relentlessly and continuously picked up on any fuzzy logic we fell into using. He watched us with the eyes of a caffeine-crazed hawk as we prepared our units for our underwater escapades; and once in the water we were on a very short leash and ANY moment of distraction or deviation from our plan resulted in yet another simulated failure and drilled contingency action. In short, he treated us like the rank novices we were and took no account of the combined 30 or so years of technical diving experience, and technical instructing we had between us.

Actually, that’s a lie. He did make a special mention of all those open circuit dives we had made. And that was what brought things into focus. “You guys,” he told us, “are swimming in dangerous waters.” He explained that we had to understand and believe that we were right back to where we were when we first started diving open-circuit scuba. We had to plan and dive beginner dives again and not be tempted to think that it was ok to dive to 60 or 70 metres because we’d done that on open-circuit a thousand times.

“It doesn’t matter much,” he said, “how many dives you have or where you’ve been on open-circuit. That was the stone-age and is all in your past. You are starting with a clean slate now, and it’s important you learn to paddle around in the shallow-end of the pool before you attempt to swim the English Channel!” (He’s a Brit.)

Now here is the cool part. As soon as he let us loose with cards that said we were certified to dive without adult supervision, we starting to rack up the hours on the type of dives we had not done for years.

We went back to shallow wrecks we had ignored for more than a decade and a half. We planned weekends of multiple two-hour dives in sheltered little spots we would have swum right by if we had been diving open circuit. We relearned the simple pleasure of gradually working around a very much narrower comfort zone and competence level. We practiced bail-outs, we obsessed, we had great fun, and in the final analysis, we changed back to being a little more multi-dimensional in our dive planning and dive execution. I think it’s fair to say that becoming a weekend CCR diver, improved my OC skills.

Oh, and Truk Lagoon. Well, a story for another day, but we worked hard to build our competence and it paid off. What incredible fun to dive a CCR in that environment, even if we did opt to give some of the deeper wrecks a miss… you see, as far as the CCRs are concerned, we’ve only been diving a year.

Test dives in a PINNACLE Aquatics V-Skin Inferno Suit

steve wearing a Pinnacle infernoI hate being cold, and always have. Perhaps it has something to do with where and when I was born, but looking back on the first 15 or 16 years of my life, much of it seems to have been spent feeling miserable because of the cold.

Now, with the bleak weather of England and non-existent or rudimentary central heating a long way behind me, my special hatred is reserved for being cold when I’m diving. Sometimes it cannot be avoided and I have to dive in cold water but I don’t like it at all and take extra precautions regarding mild hypothermia and narcosis when it has to be done.

Most of the time, in fact almost 100 percent of my dives are conducted with me wearing a drysuit. I own several and use them even in warm water. I say almost 100 percent because occasionally I get to dive in water that’s really warm — warmer than 28 degrees (that’s a little more than 82 degrees if you’re more familiar with the German physicist’s scale rather than the Swedish astronomer’s one). On the all too rare occasions that this happens, it’s more comfortable to dive wet. The only issue is, that if the dive profile is deep enough to squish neoprene – which is often is – all that nice thermal protection goes away as the suit becomes thinner and thinner. At trimix depths, you can almost read your pressure gauge through any wetsuit thinner than 5 mm. And, guess what, it gets cold down there!

So, wouldn’t it be nice to have something that didn’t get squished as you traveled deeper so that its thermal protection was virtually unaffected by depth? The added bonus of this feature of course would be that you wouldn’t have to slap a bunch of lead on yourself to overcome the buoyant effect of a 5mm-thick layer of rubber while bobbing around on the surface, only to find yourself marginally over-weighted on the bottom as it gets flattened by ambient pressure.

Now I wasn’t really thinking about any of this when I bumped into Corey Gordon from Pinnacle. Years ago, I owed a Pinnacle wetsuit. It was awesome. Build like the proverbial brick privy and pretty comfy. It lasted several times longer than anything else, but finally it did go meekly to a garage sale or church bazaar. I asked Corey if he had something similar for me now. Perhaps a 5 mil Cruiser one-piece. He told me he had something better.

The PINNACLE Aquatics V-Skin Inferno Suit is NOT your average wetsuit. To begin with, it’s not thick neoprene… it’s a tri-laminate… stretchy Lycra on the outside and various thermal linings keeping the heat in and cold out on the inside, and a breathable membrane between them. According to the marketing hype from the copywriters at Pinnacle, it is their “latest innovation separating the thermal component out of the wetsuit so that it can be used in any watersports activity.”

As an ex-advertising copywriter and diver, you’d be forgiven for assuming I know what that line means… I don’t, but the suit works and delivers a lot of warmth without buoyancy in the water, and fair amount of wind resistance on the surface.

My educated guess is the 320 gram merino™ fleece used in the lining for diver’s chest and a more traditional merino™ lining in the back and sides help do the job at depth. Corey explained to me that the V-Skin is about the equivalent of a traditional 3mm wetsuit. That may be the case on the surface, but I think it’s warmer as you go deeper. It’s that crushing effect. Any “normal” 3 mm wetsuits at 30 metres is a lot thinner and affords its user less thermal protection. The V-Skin Inferno doesn’t get crushed the same way and its thermal protection is less affected. Hence it’s warmer.

My subjective assessment is that the Inferno is warmer… significantly warmer than a 3 mm wetsuit. Moreover, the V-skin feels more comfortable than a wetsuit both in and out of the water. In part this is due to the material, which is more pliable and lighter than neoprene – so it moves without putting up a fight – and little innovations (damn those copywriters) like the underarm panels which are a different more breathable material than the rest of the suit.

Reading through the technical bumf – done after a few hours experience wearing the suit and wondering how come it is so warm – I found out that the official explanation is that a Merino™ lining holds more water than a traditional “manmade” wetsuit lining., and unlike non-wool lining also retards water circulation throughout the inside of the suit. So, once your body heat has warmed that water, the water is held inside the fibers of the Merino™ lining and kept there by PINNACLE “sealing systems.”

And while on that topic, the V-Skin does not fasten with a zip. The only zip on the suit is the one attaching an over-the-head velcro closure flappy thing. So, to don the V-skin, you enter through the shoulder opening and pull it on. This take a while to get used to, but keeps everything snug up and well fitted around your neck and shoulders. You can zip out the simple collar arrangement I had and zip in a built-in hood… which I have not tried.

I also have not tried using the V-Skin as thermal protection under my drysuit. But Corey assures me I’ll like it. Perhaps, we’ll see. If it’s anywhere near as comfy and warm as wearing it in place of a traditional wetsuit, I probably will.

Anyhow, winter is coming and many of us head off to the tropics to dive as it gets colder at home. And if you are in the market for a new idea in thermal protection, one that’s comfy on the surface, surprisingly warm at depth, and that drys quickly and fits easily into a carry-on, check out the Inferno.