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.

GETTING SIDEMOUNT TANKS TO BEHAVE THEMSELVES AND SIT WHERE THEY SHOULD

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.

sidemountTanks1a

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.

sidemountTanks4asidemountTanks2asidemountTanks5asidemountTanks7bsidemountTanks6a

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.

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.

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?

GETTING DRESSED

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.

BEGIN WITH LEFT-HAND CYLINDER

  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

 

MOVE TO RIGHT HAND CYLINDER

  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.

FIRST IMPRESSIONS
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 HARNESS
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.

THE BUOYANCY CELL
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.”

BUNGEES
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.

LOCATION OF CONTROLS
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.”

DIVING THE SMS75
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.

WHAT I WOULD CHANGE
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.

CONCLUSIONS
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.

 

A FEW DETAILS
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.
_____________________________________________________

IN CLOSING
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.

HOLLIS sms75 iNSIDEHOLLIS sms75 outSIDE

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

FREE C-CARDS…

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.

NOTICE TO BORDER / AIRPORT SECURITY PERSONNEL

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:

http://www.othree.co.uk/products/thermal-15/pbb-2.aspx

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.