How to get the most from a technical diving program/course

LongO'THREE

A common question is “What skills should I practice before my class with you?” The question is basically the same regardless of the course in question: intro-to-tech, full cave, it doesn’t seem to matter.

Oddly enough, the least helpful answer, is to send out the list of skills published in the instructor’s guide, and nothing else. Well, I guess it’d be less helpful not to respond at all, but a bare list of skills without any guidance, order of importance, value, or expectation of performance, doesn’t really tell much of a story; and certainly, is unlikely to help anyone prepare in a meaningful way. For example, what does adequate predive planning (taken from the standards for a major tech agency’s Cavern Course) mean in the real world?

If you’re signed up for a technical diving class this winter, next spring or whenever, and you’re wondering how best to prepare for it, the following tips may help.

First: if you haven’t already, speak with your instructor. Ask them about the class, get an agenda… what happens on day one, day two, etc. Ask for a breakdown of what they expect you to show them on each dive. Ask about their expectations regarding performance… what’s a pass, what’s a redo? Find out how much course time is practice time!

This last point is vitally important. A good class with lots of inwater time, will get you started on the road to building good habits. For example, the key to success in an entry-level cave or advanced wreck program is having enough time doing dryland drills to get the subtleties of a task – such as body position, where to point a light, how to hand off a regulator – refined enough to demonstrate well.

Secondly: study the equipment list, work out what’s gonna be a new experience for you, and practice how to use it. Reels – essential in so many tech programs, especially cavern, cave, wreck, and deco – are not all created equal, and even students who have first-class models, get screwed by their reels almost as soon as they get into the water. If you’re determined to buy BEFORE you start the class in order to get some practice, think simple and avoid gadgets. Here’s a model I use and recommend.

lightmonkey400

Also, most reels – including the one from Light Monkey shown above – come from the manufacturer loaded with too much line. It swells in water and with use, and falls off the edge of the spool. Take off line until there’s a half centimeter minimum of reel’s (or spool’s) body showing above the line. Here’s a picture of mine…

mylightmokey-200Notice, it is a similar reel (this is the 200 and the 400 is shown above), same manufacturer, but with line removed and a loop of equipment line added for the double-ended clip to make it hang a little more easily when stowed.

Also, learn where the new gear is going to be stored. Develop the muscle memory (the habit) of knowing how to get at it and then how to restow it. Every cave instructor has watched as one of their charges spends minutes searching for a line marker or struggling to stow a backup light.

Thirdly: relax. Arrive at your class rested and ready to learn.

And lastly: There is something called “instructor-induced narcosis.” It sometimes kicks in as soon as a student’s head disappears below the surface. Most instructors are expecting it to happen, and it usually has more of a negative effect on the student than the instructor. So, don’t sweat it! Take a deep breath, work out where things went wonky, try again.

Most of all, remember grow your skills, experience, comfort zone at your pace… and have fun!

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A thought experiment concerning “team bailout” when diving CCR in a cave…

LongO'THREE

First off: Can anyone explain the rationale behind “Team Bailout?”

Hang on… that needs to be rephrased.

Let’s start with this: Is it just me or is the concept of “Team Bailout” for CCR Cave Diving just bat-shit crazy?

Yea, that’s way closer to what I was thinking…

Ok, for those of you who may not be familiar with the team bailout concept, it suggests that a buddy team diving CCRs in a cave environment – you know, wet rocks, hard limestone overhead, perhaps an hour or more from the surface – that they carry sufficient bailout gas “…to get one team member back to fresh air from the point of furthest penetration.”

In certain circumstances, this approach may sufficiently protect team members from harm, but those circumstances should not include the category of diving the vast majority of us engage in.  I believe, a better, more satisfactory practice is for EACH diver to carry MORE gas than is required to get themselves back to fresh air from the point of furthest penetration.

The arguments I’ve heard against using this more conservative tactic is: 1) carrying multiple bailout cylinders is a pain; 2) the likelihood of more than one CCR failure among a team is too slight to consider; 3) calculations for the volume of gas required in a high-stress situation adhere to a well-defined formula corrected for all variables, and therefore it is possible to calculate with a degree of accuracy sufficient to be safe.

Experience is a better guide to best practice behavior than deductive logic, and I have limited experience in this area. So, perhaps my paranoia is unjustified; but here’s a scenario we might all give some thought to before our next cave dive.

Here goes:
Three CCR divers were in the back of a low-flow cave. Each carried an aluminum 40 filled to capacity, which lumped together was enough gas to get any one of them out of the cave and back to dry land. Even at double their normal consumption rate, this was the case. Their dive was well within the parameters of team bailout therefore.

At the worst possible time, Diver A’s CCR went belly up. He could not revive it in any way, and has to bailout. The team began its swim out. A little sooner than expected, but still more than one-third of the way out, Diver A’s bailout cylinder was empty, and he asked Diver B for her cylinder. She suddenly realized that by giving it up, she will have no contingency gas herself. The surface was still a good swim away. Very reluctantly, she handed over her bottle. Momentarily distracted by her thoughts, she floated to the cave’s ceiling and took a minute to recover, which held the team’s progress to the surface still further. Stress levels in all three team members was now peaking. None of them was comfortable.

They were in fact, more small failure, one additional glitch away from a total melt-down. A surprisingly short while later, Diver A – who had been thinking for the past several minutes, what would happen if he got a bottle with a dodgy regulator or had a free-flow, and whose respiration rate had understandably elevated – once again was down to seeds and stems. This time in his second bailout. He turned to Diver C. Diver C had been thinking about this hand-off for a while. He was VERY uncomfortable donating his gas… however, he did so. Several minutes later, the team arrived in the cavern area. Diver A had barely sufficient gas to conduct a safety stop, but did so. Just as the team left the overhead, his regulator began to breath very, very hard.

On shore, while shucking their gear, the group was uncharacteristically silent, each with their own thoughts. What do you think the outcome of this incident was:

  1. This group did not cave dive together ever again
  2. This group rethought their bailout strategy
  3. This group  continued to dive team bailout

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Fixing a lack of skill with complex gear… Nah, try a swimming pool!

Nick Hollis in SMS75 Hollis SM harness

Nick Hollis of Hollis Gear showing some skills in swimming pool like conditions…

Few of us learned to dive without the help of a buoyancy device of some sort. Not to say that wearing a jacket-style BCD, sidemount harness, or backplate and wing automatically gave any of us pin-point control over our position in the water column: it certainly did not!

The vast majority of the divers — sport, technical, rebreather, open-circuit, whatever — earned that particular skill with patience, perhaps a little help from a buddy or mentor of some description, and a bunch of practice.

Swimming pools or ‘swimming pool-like conditions’ (warmish, reasonably calm, clear-ish, current-free shallow water), are awesome for gaining something approaching buoyancy control right from the first open-water class: and then fine-tuning that skill by return visits as often as practical. I will still take time, whenever I can, to simply “hang about” in the water. A visit to the pool is a great place to test new gear, adjust weighting, check that old favorites still work the way you want them to.

In fact, if you are an instructor looking for ways to increase student comfort, add to general diver safety, and build on the basic skills your students learn on your courses, you’d do well to offer a few extra hours of pool time regularly. I have a buddy whose open-water students leave her classes with demo-quality buoyancy control and near-perfect ‘cave trim.’ Her secret is additional pool time, which her students gladly pay a little extra for because she’s taken the trouble to explain the benefits of buoyancy control to them. They get it: they know it takes a bit of work: and they are not looking for a fast fix.

So, imagine my disappointment to see an ad for a piece of kit that is such a convoluted bunch of “Heath Robinson” engineering that at first I thought it a joke. The product, and it is real apparently, is pitched as: “An industry standard premium diving jacket, dive computer with connecting links to allow the computer and jacket to manage diving processes according to the selected settings just like an aircraft autopilot.”

What have we come to when the simplest of devices, and a little practice to master its use, has to be replaced by something with Catastrophic Failure (or something else with the initials C-F) written all over it.

Please, if you want to get your buoyancy squared away because it wasn’t taught to you as a beginner, take a cavern or intro-to-tech class from a good instructor. Contraptions that offer instant mastery through technology are like magic pills that promise to shed pounds of belly fat without diets or exercise. The word to describe this type of promise is bullshit.

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A rare honor for a dear friend

explorer-in-residence-jill-heinerth-1

Jill doing what she does…

Someone once told me that as a community, technical diving suffers from a lack of real role models. He said that’s is not that there is a particular lack of great projects going on, or important discoveries being made. “There’s a tonne of great news out there!” he said. “It’s just that the news and personalities behind it are quashed by infighting and jealousy…”

That’s a pretty damning, really bleak commentary, but during the many years that have passed between him saying it, and now, there have been times when I’ve been inclined to agree with him. However, today, the technical diving community got some great news, and perhaps we can all be a little pleased… and proud.

Jill Heinerth has been appointed EXPLORER-IN-RESIDENCE by The Royal Canadian Geographical Society. This is a first, and to quote from the RCGS website, the “Explorer-in-Residence Program [is intended] to foster greater awareness among Canadians of the expeditions and field research being carried out by the nation’s top explorers, scientists and conservationists.”

Now that is cool, I don’t care who you are… that is awesome.

Immensely pleased and proud to call Jill a friend, and to say that she and I have worked on a couple of projects together… and she helped to make them fun, safe, and productive.

Hope you will join me in wishing her all the best, and giving her what really is a well-deserved pat on the back… and perhaps a glass of nice red wine!!!

http://www.canadiangeographic.ca/blog/posting.asp?ID=2070

Want to ignore the rules? Then do this…

There really are no scuba police, and here in most of North America at least, government bodies give the diving community the closest thing to a free-rein. We can, in essence, do exactly as we please. We can dive without training, ignore warning signs, flaunt best practice, exceed both whatever certification we have and the experience earned on previous outings. We are free agents. Great stuff.

But the downside is awful. A couple of days ago, I read of another stupid death — highly preventable and caused by several breakdowns in the system… that tragic alignment of holes in the safety net that which is in place to help diving “accidents” NOT happen.

What’s frustrating about many of the deaths we read about online, in diving magazines, and in diving forums, is that the people involved had been warned. At some point, either in their training or general involvement with the diving community at large, they had been told what they had planned, was foolhardy or against best practice.

But they went ahead anyway.

Just as sad is that their behavior does have the potential to change the status quo. Their silliness may create a situation where some agency or quasi-government entity starts to pay attention to our activities… and arbitrarily start to shut things down.

I am reminded of something my mate, Wayland Rhys Morgen suggested for anyone who is about to — either figuratively or actually — hand their beer to someone and say: “Here, watch this…”

The next time you intend to deviate from best practice, take a piece of note paper and divide it into two columns. Write in block letters at the top of the left-hand column: “What people usually do.” On the right, also in block letters, write: “What I am going to do instead.” Then in the appropriate column write clear, concise language an explanation of each behavior associated with your planned dive. So, these ‘behaviors’ would cover things like analyzing and labeling gas cylinders, limiting depth and duration according to your training, recent experience, and the vagaries of the environment… stuff like that. Read it back to yourself — both columns — then sign and date it. Then give it for safekeeping to someone you trust: lover, spouse, son, daughter, best buddy, favorite cowgirl. It really does not matter much to whom, just hand it over. Tell them to give it to the people or agency that leads the inquiry should something bad happen to you on your adventure.

Surviving the Rottweilers

LongO'THREESeven tips to help protect you when things go wonky underwater

You may have read somewhere that underwater emergencies are rare. I’m not so sure that rare is the best way to describe them.

While underwater incidents causing bodily harm or death may be infrequent, close encounters with potential disaster are frightenly common. Spend a week or so at a dive resort or on a live-aboard, and you’re guaranteed to hear stories that support this view. “I ran out of air,” “we got separated from the guide and had no idea where the boat was,” “We ended up way deeper than expected,” “My computer went into deco and I had no idea what to do,” “My regulator started to spew bubbles and I panicked… I did not know what to do,” “We skipped our safety stop,” “I felt odd and confused, but managed to hit the inflate button and shot to the surface,” “I signalled the divemaster but he misunderstood me and continued with the dive.”

‘Victims’ of these little brushes with catastrophe fall into three categories. Some give up diving altogether. They get the crap scared out of them and opt for golf, fishing, stamp-collecting. No foul.
Some learn from the experience and avoid the traps that painted them in a corner in the first place, and they become more informed and safer divers.

And some learn nothing. They carry with them the potential to make similar mistakes again and again… sometimes with ruinous consequences.

Here are seven strategies that may help divers enjoy their diving, and avoid becoming a statistic.

      1) Learn to say no! Too many new divers are fooled into believing that it’s OK to do trust-me dives with a dive guide or divemaster. They may have a good sense that diving once or twice a year does not prepare them for a 40 metre-plus dive (that’s 130 feet or more), in current, with rented gear, but a divemaster, instructor, sales-person talks them into doing it. This is dangerous bullshit. No agency condones this type of practice, but it is common in many dive resorts, and needs to be stamped out.

 

      2) Learn your limits and stick to them. There is nothing wrong with pushing yourself to learn and grow your diving experience and comfort zone, but be realistic about your starting point. Being an occasional diver means you start from zero at the beginning of every dive trip. Scuba skills are perishable. Even experienced cave instructors take the time to “brush up their skills” if they have been out of the water for a while.

 

      Even if you are lucky enough to dive every week, understand that your experience, training and gear limits the types of dives that you can safely undertake. Listen to your inner wimp.

 

      3) Learn self-reliance. Too many “rescues” end up in disaster or near disaster for all participants. Get training, learn what kit to wear to help deal with gas emergencies, PRACTICE. Most of all, STOP, THINK, ACT, REASSESS.

 

      4) Maintain your kit, and use a checklist when you assemble it and when you inspect it prior to EVERY dive. Equipment problems are the easiest underwater emergencies to avoid. Don’t fall into the trap of believing that something is good enough… if it “ain’t perfect” don’t dive with it.

 

      5) Plan your dive… Dive your plan. Understand the risks, make sure everyone is capable of doing the dive, and ensure everyone have the skill and kit to deal with contingencies should they arise.

 

      6) Be aware! The best way to deal with a diving emergency is to stop it before it gets out of hand. The vast majority of diving emergencies begin as small inconveniences that cascade rather like dominos falling over. Keep an eye on your buddy(ies), be aware of changes in the conditions, monitor yourself. The best blanket advice is to take things slowly.

 

        7) Have an escape strategy. When something goes pear-shaped, the top priority is to make sure everyone has something to breathe… next is to get yourself and your mates as far away from the spinning fans as possible. Cave divers talk about always having a continuous guideline to the surface. Sport divers can take a lesson from that: Always know the location of a safe, protected exit… in other words, someplace where you can surface and be found or find your way to your entry point.

Steve Lewis is an explorer and experienced cave diver, who has been teaching technical diving programs for more than 20 years. He writes and lectures on topics related to diver safety in North America, Europe and Asia.

Adventure Tourism “Under the Bell”

LongO'THREEDiving Bell Island Mine

In 2006, while visiting Canada’s newest and easternmost province to dive on four excellent WWII wrecks, I was asked if I had any interest in leading a small expedition to check out the flooded Bell Island Iron-ore Mine in order to help determine if it had the potential to become an adventure dive destination.

In January/February of the following year, that expedition laid around two kilometers of line, discovered countless artifacts and items of interest. We also lost a valued team member during the exploration. Despite Joe Steffen’s untimely death, our final report recommended the opening of portions of the mine to qualified divers.

Unfortunately, during the intervening years, Bell Island Iron-ore Mine has not been added to the list of North America’s ‘must-visit’ dive sites. The exceptional, matchless cultural and historic story it has to tell its visitors in face-to-face meetings, is left untold.

However, after three days of diving in the mine filming for a TV show this past week, I have to say: I hope that changes soon.

The mine is a fantastic heritage resource. It gives us vivid insight into an important part of Newfoundland’s history and the daily lives of Bell Island’s working people. It also connects the region to what remains perhaps the most iconic conflict of the 20th Century.

Uniquely, Bell Island Mine focuses several major tourist attractions: firstly, the current mine museum and underground displays, the four ore carriers resting on the ocean floor a few hundred metres from shore, and of course the surrounding scenery: truly all remarkable experiences. Secondly, the portion of the mine workings now underwater have a very special appeal. The mine is filled with artifacts – machinery, tools, even the graffiti left my miners – and it fills its visitors, who still number less than 20, with a sense of wonder.

As a viable tourism product, certainly the potential buyers of structured and regulated physical access to the flooded Bell Island Mine are limited. Diving in an overhead environment (cavern, cave and mine diving), represents only a small percentage of the total scuba-diving market. But it is an influential population. Clearly, divers trained and equipped to dive in the Bell Island Mine will never flock to the area by the truckload. However, what the flooded mine on Bell Island has to offer, should be made available to those who wish to visit. The quality of the cultural and historic experience are simply too great not to be shared.


What follows is the text of an original article I wrote several years ago for TDI’s eNewsletter. Actually, the brief for the article was “The Benefits of International Dive Travel” but I used it as an excuse to promote diving in Newfoundland, the value of diving the Bell Island Iron-ore Mine, and the wrecks of four merchant ships sunk while loading with iron ore during WWII.

 

OK, before drilling into a few of the real benefits and surprises waiting for us when we decide on International Dive Travel, and certainly one of the most interesting associations with “foreign lands” in my diving career, we need to walk through a very quick geography lesson, followed by an equally brief history lesson!

Newfoundland is a big island off the east coast of North America. In fact, it is the most easterly point in the whole of North America and Signal Hill outside of Newfoundland’s capital St. John’s is where Marconi set-up his apparatus to receive the first radio signal sent skipping across the Atlantic from Cornwall, England in 1901. Like most of that part of the world, Newfoundland is rich in Celtic culture thanks to the influence of its early Irish-Ulster-Scot settlers, and the locals still sound more Irish than American. The waters surrounding the island are chilly (think icebergs drifting down from nearby Greenland… even in June!), are filled with the most amazing marine life — including many species of whale – and are home to four of my favorite shipwrecks anywhere in the world. We’ll get to those in a few moments.

When the Second World War erupted in Europe, Newfoundland — which today is a Canadian province — was part of Great Britain. Hence, when that country’s Prime Minister declared war on Nazi Germany in 1939, Newfoundland was automatically part of the Allied headcount. Canada followed close behind them, but it was not until a very closely fought referendum ten years later in 1949, that Newfoundland joined the Canadian Federation to become one of its ten provinces.

So, what about those four favored shipwrecks?

Just outside of the city of St. John’s, in the middle of Conception Bay, sits a small blob of land called Bell Island. During the years leading to the beginning of WWII. Bell Island had a very productive mine that exported iron ore to steel mills in several countries, including Germany. At the outbreak of war, steel mills, a little to the south of Newfoundland in Nova Scotia, accounted for about a third of Canada’s steel production vital to the British war effort. With shipments from the Bell Island Mine to German factories cut off because of the war, it was inevitable at some point that the Germans would attempt to interrupt production and throw a “spanner in the works” for the flow of steel to Great Britain. And interrupt they did.

On the night of September 4th, 1942, a German U-Boat sneaked into the anchorage at Wabana, Bell Island where ships loaded ore to be carried away to various “customers”. The next morning and within sight of the guns of the Bell Island Battery, the U-Boat sank two ore carriers moored at the loading docks: SS Saganaga and SS Lord Strathcona. Twenty-nine men were killed in the attack, all of the victims were seamen aboard the Saganaga.

The Battle of the Atlantic had suddenly come to within a few hundred metres of North America’s shoreline.

The strategic importance of the mines on Bell Island did not diminish of course, and just a couple of months after the first attack, a second U-Boat crept into Wabana and found several ore carriers at anchor.

The U-boat captain fired a torpedo at the 3000-ton Anna T. It missed and exploded ashore ripping into part of the loading dock and disturbing the sleep of many inhabitants on the island. In the next several minutes, two more torpedoes were fired at SS Rose Castle. Rose Castle sank, taking twenty-eight of her crew with her, five of whom were native Newfoundlanders. The Free French vessel PLM 27 was the second target. She sank almost as soon as a torpedo hit, taking twelve men to the bottom of the bay with her.

In the space of less than 15 minutes, two ships, several thousand tons of ore and 40 men had been lost. The U-boat escaped even though there were three allied navy escort vessels in the area.

The four Bell Island wrecks sit today at reasonable depths (the PLM 27 the shallowest at around 23 metres / 75 feet, the Rose Castle the deepest at 43 metres / 145 feet), and within a radius of a few minutes boat ride of each other and only a stone’s throw from land.

When I was first invited to dive the Bell Island wrecks, I must admit that Newfoundland seemed as remote to me as the dark side of the moon. Newfoundland was, at least in my ignorance, nothing but folk singers, remote fishing communities, moose, and wild, wild countryside battered by strong winds and salt spray off the North Atlantic. Through a number of visits over the following few years, I discovered that it was all of this and so much more.

The wrecks were one of the first surprises. Four shipwrecks each more interesting and more crammed with history than the last. After the first handful of dives, I christened the area Truk Lagoon North. Perhaps using a little poetic license but the things that seemed common to both areas were history, the awe inspiring evidence of the destructive power of torpedoes, the sadness of the lives lost, and the contrasting beauty of the creatures that had made the wrecks their home. Like many divers, I have a fascination with WWII casualties and the story all wrecks have to tell those with time enough to listen. Like the Japanese fleet in Truk, The Bell Island wrecks are master story-tellers.

One of the best pieces of luck I had on my first visit to Newfoundland and Bell Island was meeting Rick Stanley. Rick is a proud local who owns and operates Ocean Quest Resort, which was home-base for our group during our visits. Rick is a strong advocate for all things relating to Tourism for Newfoundland, and almost single-handedly has promoted responsible diving on the wrecks, as well as campaigning to have them designated as a war grave and a protected site.

During all my visits to the island, he and his staff, seem to go out of their way to make our group welcome and introduce us to local hospitality… including the infamous Screeching-In Ceremony.

Screeching In is when visitors (people from away, is how the locals refer to tourists) are made honorary Newfoundlanders. Space prohibits a blow-by-blow account of a true Screech In ceremony but proceedings include strong rum, eating local delicacies such as cod-tongue, hard-tack (ship’s biscuit) and dried capelin (a small smelt), singing, dancing, and “kissing the cod” which really does involve getting close and personal with a large dead Atlantic Cod (gadus morhua). Having survived being “Screeched In” during several trips, I can honestly say, it is one of the most bizarre and funniest things I’ve done during the course of several dozen dive  trips.

Partway through my third trip to dive the Bell Island Wrecks, Rick Stanley asked me if I would be interested in putting together a group of divers “Capable of exploring the Bell Island Mine.” Of course I said yes.

The mines were abandoned when it was no longer economically viable to operate them; but the closure was oddly abrupt.

The mines on Bell Island opened for commercial mining in late 19th century and were once the world’s largest submarine iron ore mine with passages occupying an area under the seabed of Conception Bay roughly five kilometers by five kilometers or approximately nine square miles in size.

The mine that Rick was interested in having surveyed and accessed — and that was the project’s main aim — had been closed since Christmas 1949. The story goes that the workers downed tools for the holiday and were never allowed back into the workings.

Rick and the Bell Island Historical Society were curious to have a team of divers explore the mine system — or as much of it as practical in the 12 days available — and look for evidence of cave-in, collapse, artifacts and other things that might interest a different type of visitor than the ones currently coming to the mine museum sitting at the old entrance to Mine Shaft Two.

The questions they wanted answers to where simple: can it be dived? Is it interesting enough to attract divers? Are conditions supportable for regular visitors? There were some side issues that needed to be addressed, but the hope was to open up a unique form of adventure tourism for the island and its economy.

With a background in Tourism Marketing, I was certainly curious enough to take Rick up on his offer, and set about building a team that would be able to pull things off. After a simple exploratory dive in July of 2006, we set a target date for the following January/February, and started planning.

Our goal was to investigate as much of the inundated mine as practical within the short time available. We knew the water would be cold, and because of the surface support needed, we also knew that our efforts would have to be focused on a time when normal tourist activity would not interfere; and that meant winter which also would be cold.

I was lucky to find the perfect group of men and women who were not daunted by the challenges that the season, the logistics, and the challenging dive site would present to us.

Newfoundland in the heart of winter is an interesting study. Stuck as it is with both feet in the Northern Atlantic, and its face weather-beaten by winds coming off the glaciers of Greenland or Labrador, it is not for the faint-hearted. Several of the team where Brits whose experience with a real Canadian winter had been limited to movies and books. They got to experience a true winter storm on arrival, and several of us had plane delays getting into St John’s airport. My plane was almost on the runway but the pilot aborted and we headed back to Halifax International with our tail between our legs and our hearts in our mouths.

But eventually, all 16 of us were together in the lounge at Ocean Quest Resort, sorting gear, knotting line, and pumping gas.

During the following two weeks, the team surveyed the mine looking for any evidence of cave-in or collapse in the mine shaft and laid permanent guidelines from the surface along the main shaft to a depth of approximately 50 metres. The seam of iron ore slopped at an angle of approximately ten degrees and continued many thousands of metres under the overlay of ocean floor below Conception Bay. In addition to the main line, four ‘jump lines’ were laid in side passages. The initial plan was to extend these side passages (roughly horizontal) approximately 300 metres east and west of the main shaft. Overall a total of 2km of line was laid in the mine.

The search for artifacts left behind when the mine was abandoned turned up mine equipment, personal effects such as lunch boxes, and we discovered graffiti, drawn by the miners using the soot from their carbide lamps. The system was mapped sufficiently to enable the conclusion that the mine would make a challenging diving destination for cave divers to explore.

Every overhead environment presents divers with a number of challenges well beyond the scope of recreational diving. As well as the obvious threats to the team’s well-being — gas management, navigation, light, depth and the cold — the health of one of our team played a role. On Sunday, February 4, Joe Steffen, well-known in the diving communities in both the Great Lakes and North Florida, suffered a massive embolism and died. Joe perished in a few metres of water just a couple of minutes from the surface operations. Ironically “Iron Man” had an undiagnosed problem with his lungs which did not show up during a medical he’d had before joining the team from his home in Ohio, and attempts to revive him at the dive site and the medical facility adjacent to the mine were unsuccessful.

We lost a great buddy, and Joe — a career police office — left behind a wife a young son, and a daughter, as well as many, many friends.

In consultations with the various sponsors — which included TDI, Fourth Element, Whites, the NACD, and Ocean Quest — as well as local authorities, the exploration of the Bell Island Mine continued and its success was dedicated to Joe’s memory.

The following year (2008), Joe’s widow, Jennifer, visited Bell Island for a memorial service which included two of the team (Mike Fowler and Steve Lewis) placing a memorial plaque and an urn containing Joe’s ashes in the main shaft of Bell Island Mine No. 2.

Tourists continue to visit the Mine and divers enjoy the four wrecks that sit above its vast network of passages, but underwater operations at the mine await further work.

The team consisted of: Rick Stanley, Debbie Stanley, David Sawatsky (diver and map-maker), Phil Short (diver, deep explorer), Ralph Hoskins (diver and record keeper), Vlada Dekina (diver and expedition photographer), Dave Clemmens, David Powell, Mark McGowan (dive safety officer), Stephen Phillips (diver), Aaron Bruce (diver), Mike Fowler (diver), Joe Steffen (diver), Steve Moore, Susan Copp, Steve Lewis (diver and expedition leader).

Setting Limits for cave diving: How much bailout gas should a CCR cave diver carry… and where?

Closed-Circuit Rebreathers (CCRs) are complex. Fewer moving parts than a Formula One car, and less mind-boggling than a Heath Robinson machine, but as mysterious and confusing as both to some folks.

Here’s one thing that certainly doesn’t help. When open-circuit scuba goes pear-shaped, the situation usually announces itself with gusto. Events such as a high-pressure seat failure, an o-ring giving up the ghost, a hose failing, or a manifold or burst-disk leaking, make themselves known immediately. Divers spend a huge percentage of the time during any technical training program, rehearsing a variety of valve shutdowns, regulator switches, and one or more options intended to deal with this type of failure, preserve what gas they can, and get their backsides out and to the surface with the least fuss possible.

By contrast, a CCR is not only quieter than open-circuit in normal operation, a whole category of failures arrive unannounced and quietly too. Certainly CCRs are still prone to many of the issues that plague their bubble-making dive buddies. Ruptured hoses, extruded orings, faulty handwheels, and free-flowing first stages are all possible. But in addition, there’s a whole category of sly, furtive malfunctions unique to closed-circuit diving; and each of these has the potential to cause real harm.

The default and simplest solution is to “bailout to open-circuit.” In other words, stop using the rebreather and switch to breathing from open-circuit gear to get back to the surface as rapidly as circumstances allow.

Advanced training for CCR divers puts strong emphasis on keeping the diver in CCR mode for as long as safety allows, and only bailing out as the primary option for scenarios like catastrophic loop failures or full floods, widely divergent oxygen cell readings, carbon-dioxide breakthrough, mechanical damage to primary components, etc. Cave CCR students, for example, are expected to consider all the options available to them in the event of a system failure – real or simulated. A full-cave CCR course is an exercise in complex navigation, and disaster scenario management. However, for the sake of overall safety, CCR cavers are also encouraged to bailout to open circuit if they have doubt about what needs fixing and how best to do so.

A useful phrase worth remembering is: THERE’S NO SHAME IN BAILING OUT!

Of course, as with most pieces of advice about diving, particularly cave diving, and more specifically about diving a CCR in a cave, there is a limitation. There’s no shame in bailing out… provided you have more gas then you need to get back to dryland in one piece.

And this begs the question: How much bailout gas is enough?

Calculating the answer to this is simply a question of using average depth (expressed in bar or ata), and multiplying that number by how much time it will take to get back to open water. In addition, one is advised to factor in some contingency volume for heightened gas consumption due to stress, hypercapnia, and so on. One suggestion is to work with a basic SAC rate of 30 litres / one cubic foot per minute. So using this baseline for a cave with an average depth of 20 metres / about 65 feet / 3 bar or ata, the bailout consumption rate would be 3 X 30 litres or 3 X 1 cubic feet per minute.

This calculation suggests an 80 cubic-foot cylinder (11 L charged to 200-210 bar)  would last approximately 25 minutes. Penetrations therefore would be no deeper than a 25 minute swim to the exit… where one might normally stage a small cylinder of decompression gas: usually pure oxygen.

Some divers use a slightly more conservative baseline, some slightly more aggressive. Some calculate a slightly lower consumption rate after the first 10 minutes on bailout, on the understanding that a diver will begin to regain control of his or her breathing after that time.

Another approach is the “one-hour rule.” Following this guideline, divers each plan to surface with one hour of all consumables in reserve, which includes lights, oxygen and diluent gases, scrubber, and bailout.

Whichever guideline one opts to use, the strong recommendation is to backup any seat-of-the-pants calculations by conducting simulated bailouts from various points in caves one dives regularly. These actual real-world data – with an added factor for stress – can then be inserted in calculations to arrive at a more accurate estimate.

Once one has an idea of how much bailout gas is enough, the next decision is how to carry it. Options include, about one’s person, shared among team members, drop-staged at various points in the cave.

The NSS-CDS, one of the original cave diving training agencies, suggests a dive team carries 1.5 times the volume of gas required to get a single diver out of the cave. Therefore, in the example above and a three-person team, each member would carry a fully charged 40-cubic foot bottle.

The logic behind “team bailout” is that there is, for the diver with a gas emergency, a greater level of conservatism than the acceptable norm for open-circuit cave divers. It does however demand that team stays in contact, swap tanks during their exit, and that only one unit has a problem that requires bailout.

Except in exceptional circumstances – with seasoned team members and when the basic bailout scenarios are inappropriate or impractical – I choose to carry on my person, enough gas to swim out of the cave on my own. Depending on the unit I am diving, I find that carrying two, 80-cubic foot sidemount cylinders is easy, comfortable, streamlined, and allows for plenty of time to exit from the vast majority of tourist cave dives. On occasion, for “smaller” dives or shallower profiles, I’ll strap on smaller aluminum tanks for bailout. If a dive requires a bailout volume approaching my normal carried volume, or a greater safety margin, I’ll drop stage bailout gas and/or work out a kind of hybrid personal-carry-team-dropped-stage strategy.

More than any other factor, one should be aware of the elevated gas consumption that typically follows an incident that demanded coming “off the loop” (bailing out). One also has to consider, especially if open-circuit diving is no longer part of your regular dive menu, typical consumption rates for a CCR diver using OC gear are often higher than expected. Something to do with the sudden shock of breathing cold, dry air I suspect.

In any event, remember to always have something appropriate to breathe, and plenty of it. You will never regret carrying more gas than you need.

Do some CCR training standards need to be revisited?

Lucky enough to have the option, and sometimes I use open-circuit technology because it better suits the environment and situation, but I think of myself as a rebreather diver.

Also, I count myself as lucky to be a rebreather instructor. I enjoy teaching something a little more complex, technically challenging, and arguably a wee bit more cerebral than basic open-water classes. However, I have issues with a couple of things that standards require me to incorporate into CCR training.

Let’s start with recommendations for the flavor of diluent in TDI’s first level of mixed gas training. (FYI: this is the program with a depth limit of 60 metres… that’s 200 feet American.)

The course standards require the diver’s diluent cylinder to contain 16 percent oxygen or more. At first blush this seems sensible. After all, a gas containing 16 percent or more oxygen can be breathed on the surface without ill effect… but only in open-circuit mode… and only in the majority of circumstances, not all.

Someone unfamiliar with rebreather diving, therefore (a trial juror for example), could be easily convinced that even if the rebreather was unable to add supplemental oxygen to bring the partial pressure up to a healthier range – either because of a malfunctioning oxygen solenoid or depleted oxygen supply cylinder – the diver would be “OK” to surface and get out of the water. A 16 percent oxygen mix would be, then, a good choice to breathe in these circumstances.

However, it is not. Few CCR instructors promote this option. Most – me included – would promote coming off the loop and breathing bailout gas (decompression bailout gas for example), long before surfacing.

In essence, the fact that the diluent is breathable on the surface in very limited and sub-optimal circumstances has little bearing on risk management.

One might argue that such a gas is potentially dangerous. And the truth is that breathing a trimix diluent, any diluent even air, on a malfunctioning unit or with an empty oxygen supply cylinder on the surface or close to the surface on a rebreather is a poor choice. It would be a crap shoot anyplace shallower than say 21 metres (about 70 feet American). In my opinion, the risk of hypoxia – and other complications – is too great at that depth or shallower. Best option is to bailout to open-circuit deco mix. Easier. More likely to have a happy ending.

So, would I like to have standards suggest the oxygen content of the diluent bottle be increased? No, just the opposite.

The issue has nothing to do with what can be breathed on the surface. This is a red-herring in my opinion. With a functioning unit, the oxygen content of the gas within the diver’s breathing loop at the surface (the oxygen set-point) will be maintained at something like the equivalent of breathing EAN70. If the unit cannot do that, the diver is best advised to bailout to open-circuit gas… OFF-BOARD OPEN CIRCUIT NOT DILUENT.

So, the diluent on the surface issue is not an issue at all. What is an issue is what happens at depth.

The procedure of emptying the contents of a rebreather’s breathing loop and replacing it with diluent, is called, unsurprisingly, a diluent flush. It serves a couple of functions, each with a specific benefit.

Let’s look at number one function of a diluent flush. Doing so, replaces the gas being breathed with a known entity with a predictable oxygen partial pressure. That oxygen pressure is derived by multiplying the fraction of oxygen in the diluent by the ambient pressure expressed in bar or ata. So for air diluent at 30 metres the solution is approximately 0.20 X 4, which equals 0.8. And that’s what you’d be breathing after a complete flush on air, at 30 metres (100 feet). And, importantly, that is what you’d expect the readout on the unit’s PPO2 display to show you.

Reassuring when this happens. Even more so because you can then watch each oxygen sensor’s behavior as the unit starts to add oxygen to bring the loop gas up to its intended set-point (let’s say for example’s sake, an oxygen partial pressure of 1.3 bar). The speed at which the sensors respond and refresh a gradually rising PO2, and the uniformity of their display can indicate everything is functioning as it should… or that there are problems.

Now, let’s imagine we are diving at 60 metres using a diluent containing 16 percent oxygen. The ambient pressure at 60 metres is 7 bar/ata, therefore a quick diluent flush will return a partial pressure of approximately 7 X 0.16, which is 1.1 – 1.2 bar. If you were running a set-point of 1.3 bar or 1.2 bar (both are possible and common choices), a diluent flush would tell you bugger all. A diluent flush would not appreciably change the oxygen partial pressure.

In my opinion, diving to 60 metres on a diluent containing 16 percent oxygen is not the best option… actually, it’s a rather poor option, and one I am reluctant to recommend. I believe doing so takes away a valuable, vital real-time test of oxygen cell function.

Here’s my point. While 16 percent oxygen may support life when breathed open-circuit on the surface, the likelihood of a CCR diver opting to do so, is remote… perhaps a very last resort… if that. Whereas executing a diluent-flush at depth to check on oxygen cell behavior is something one might do several times during a dive.

I’m all for managing risk, and having your backside covered should the Rottweilers hit the fan, but I don’t believe TDI’s suggestion of the “correct” diluent for 60-metres dives does so… it is simply too oxygen rich. Why not suggest a 10/50 diluent on all CCR dives to 80 metres and above? It’s easy to mix and is the default diluent gas sold to divers in many, many of the dive shops I use.

At 60 metres (7 atmospheres, 200 feet), a partial diluent flush with a 10/50 returns readings of around 0.7 bar, which gives one the widest scope possible for watching oxygen cell behavior.

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The “weighting test:” are technical divers absolved for some reason I don’t know about?

When you first learned to dive, I’d bet dollars to doughnuts that your instructor explained a simple trick to help you check how much lead you should carry. It went something like this:

  • The diver enters water (at least 3-4 metres deep) with gear in place and a regulator in her mouth, with her cylinder almost empty (SPG reading perhaps 50 bar/500 psi)
  • She inhales and holds a full breath then vents all the air from her buoyancy device.
  • She hangs motionless… Quiet hands and feet
  • If correctly weighted, after 30 seconds or so, she will settle in the water and float at eye level, half her mask window below the water, half above
  • She exhales and slowly sinks

What is not commonly taught is that this test can be completed with a full tank also. The only difference being that the diver should add enough ballast after the test to compensate for the weight of gas that she will use during the dive… the aptly named buoyancy shift… otherwise she will be too “floaty” to hold a safety stop at the end of her dive.

Your first instructor may also have explained exactly why carrying too much lead is a recipe for a miserable dive. Achieving good trim, buoyancy control, presenting a streamlined angle of attack to the water, and in-water comfort can be difficult for new divers but more so when he or she is over-weighted. Hence the value of doing a weighting test: it is definitely time and effort well spent.

Of course, an alarming percentage of divers all but ignore the lessons taught by the test and dive with “a little extra lead just to be safe.” God only knows what that’s supposed to mean, but it happens too often.

Now just in case you consider yourself a technical diver and are reading this thinking: “Bloody sport divers… always getting it wrong;” I believe that the worst offenders in the over-weighting challenge are technical divers. That’s right buddy, you and me.

The Balanced System Misunderstanding
The term “balanced system” actually describes three important aspects of gear selection and configuration. The first is the outcome of the balancing act between buoyancy and gravity, and whether the diver and the gear she takes into the water floats or sinks when it’s all put together. (Simplified to does it float or does it sink.) Secondly, the weight of ballast that could be ditched should the Rottweilers hit the fan and the diver has to swim for the surface without a primary buoyancy aid. (For a sport diver this ditchable weight is usually his/her weight belt; and for a technical diver, it might be stage bottles etc.). Thirdly, where the ballast should be located or carried since this will affect the diver’s trim and issues with the angle of attack as he or she moves through the water.

For a technical diver, understanding and addressing all three is necessary — just as it is with his or her sport-diver buddy — but the nuances of all three issues are more complex to calculate and more finicky to arrange for anyone engaged in tech diving profiles.

You may have read before in various onLine postings and perhaps textbooks that “a balanced system is one that a diver should be able to swim to the surface even with a failed [primary buoyancy cell].”

The ability to get themselves and as much of their life-support system back to the surface is certainly something technical divers should strive to achieve, but without any actually thought, calculations or in-water testing, it really cannot be assumed. Many do.

For example, the buoyancy characteristics of most sets of traditional North Florida Cave Rigs (steel backplate-mounted and manifolded doubles) means most would have a hard time to qualify as balanced at the beginning of a dive when fully-charged with gas.

For many technical divers, their backmounted doubles (and the gas they contain) constitute the vast bulk of the ballast they carry. So in effect, they often carry very, very little ditchable weight… if any. If they are over-weighted, they have nothing to ditch. In an emergency, swimming a set of steel doubles up to a safety stop and holding position in the water column for even a few minutes would be close to impossible and certainly stressful for these people.

Luckily, primary buoyancy cell failures are rare, but even so, divers who opt for steel doubles need to be aware of the potential challenges their kit presents them with… you can’t take off one tank and swim the other one to the surface when wearing twin cylinders!

Sidemount users have things slightly easier because they can unclip one primary bottle, dump it, and surface while breathing from the second. But their systems present challenges too. Rebreather divers also have a special balanced rig paradox to sort out if they happen to have a “dramatic moment” at depth.

Weight Changes During Your Dive
As a diver, especially a technical diver or one who aspires to become one, and contrary to the assumptions made by the Ideal Gas Law, we need to understand that gas has mass. For non-scientific applications this means gas weighs something and as it is consumed during a dive, the drop in gas weight is what contributes to buoyancy shift.

I don’t usually speak American Standard Units, but you might and if you do, you should take note. A cubic foot of air weighs approximately 0.0807 pounds. Perhaps more useful is that 13 cubic feet of air equals about one pound. Therefore, a diver carrying a couple of 130 cubic-foot steel cylinders, who has consumed just half of a full air fill during her dive, will be approximately 10 pounds lighter than when she started!

For the rest of the world, one thousand litres of air – assuming standard content, pressure, and a temperature of 0 degrees – will weigh around 1.29 kilos… slightly less at higher temperatures. So, a diver starting her dive wearing two 10-litre cylinders charged to 230 bar is carrying a little less than six kilos of gas with her!

Another thing that may affect weighting is the type of thermal protection being worn. For instance wetsuits compress and the lift they provide will decrease as depth increases. Drysuits and what’s inside them providing insulation, also compress at depth and provide less lift.

So… Let’s Determine How Much Ballast
The first step of the weighting test for a technical diver is similar to the one used by sport divers.

Work in a spot where there is sufficient depth to submerge but not a wall dropping to trimix depths. The six-meter / 20 –foot platform at your local quarry should be perfect. This is your test zone.

With minimal gas in your cylinders (a little less than one-third of their working, rated volume), no gas in your buoyancy cell, just enough gas in your suit to be comfortable (assuming you are wearing a drysuit), check to make sure you are able to maintain eye-level surface float with your lungs full. Exhale, and you should begin to sink slowly. This is the balance between buoyancy and gravity that you should aim for.

If you cannot sink, your rig is under-weighted. If you cannot float without adding gas to your buoyancy cell or suit, it is over-weighted.

Step two is a little more complicated.

Below where you completed step one, perhaps on that platform at six metres / 20 feet, have a collection of small lead weights that equal the weight of the gas that is “missing” from the cylinders you wore in step one. Use a handful of small weights… one kilo or less each. Have enough to make up the weight of a full fill and perhaps a little more. Use the 1000 litres weighs one and a quarter kilos, 13 cubic feet is one pound guideline.

Now descend to the platform, check your gas volume… now’s not the time to run out of something to breathe. Pick up all the weights, put them in a pouch, in a pocket, in a mesh bag, whichever works for you, and kick for the surface. Remember, no gas in the buoyancy cell. You CAN put a little in your suit, but don’t overdo it. The test is to calculate a balanced rig not to cheat.

This additional weight simulates your in-water weight at the beginning of a dive. If you can make it back to the surface, great. If not, relax, sink back to the platform and take out one small weight at a time until you CAN make it to the surface. Take note of by how much you were over-weighted when you initially tried to make it to the surface. Note how much lead you dropped before you were able to swim up.

You might say that whatever weight that is, represents how many litres or cubic feet you would have to breathe or dump to get back to the surface should something bad happen at depth. Not a terrific situation.

Frankly, being over-weighted by ANY amount has the potential to be life-ending. It’s certainly not smart. You may need to adjust your kit configuration. Use an aluminum rather than a steel backplate, get smaller cylindersor ones with different buoyancy characteristics.

Cut out as much excess non-ditchable ballast as you can. If you need lead to achieve balance in step one of the weighting test, make sure it can be ditched. I see a lot of divers adding V-Weights between their backplates and tanks… you do the math.

Stages and Decompression Bottles
When you carry out steps one and two of the weighting test outlined above, don’t wear stages or other bottles. These are ditchable and can be dumped in an emergency when a dive is first starting and your rig is at its heaviest. However, DO consider that aluminum stages and deco bottles (the type preferred by the majority of technical divers), have strange buoyancy characteristics and may float when empty or near empty. Factor this into any considerations for holding a safety stop.

In other words, should you have a problem with your buoyancy cell and are too heavy, hand off any negative bottles to your buddy. If they are empty, too positive, and you believe they may prevent you holding a stop at the end of your dive, you can dump them because they will probably float to the surface.

Rebreathers and Bailout Bottles
Rebreathers divers use very little gas during a diveusually just a couple of hundred litres, perhaps 10 cubic feet… therefore, their gear’s buoyancy shift is minimal. However, they carry bailout bottles. These may stay untapped for months. Only issue might be that on the one dive where they have to be used, the diver will ascend with less weight than “usual,” since they’ve been breathing open-circuit since they came off the loop. Because of this, the suggestion is to do a weighting check simulating a safety stop with one or two spend bailout bottles strapped to you.

Conclusion
Making the effort to get your weighting will increase your comfort and you will be in a much better position to handle emergencies, like wing failures and other problems. Cutting excess weight will make it easier for you to control your buoyancy, and you will not be wasting as much gas continually filling and dumping your buoyancy cell during the dive.

You may also derive some benefit from buying a digital fish scale. You can use it to measure the in-water weight of various accessories such as stage bottles, cameras, lights, reels and the like. Simply zero out the scale, lower the accessory into the water, hook the digital scale to it and it will display its weight. Cool too if you want to calculate an object’s volume!!

Remember also that you need recalculate your weighting when you change something in your configuration like tanks, primary lights, regs or drysuit underwear.

Have fun and dive properly weighted.

Flying after diving… what are the guidelines?

Here’s a somewhat common scenario… perhaps one you have experienced yourself; or thought about at least.

Anyhow, here it is. You and your buddy are on a dive vacation someplace that requires airline travel… bummer, right!? Pack light. Hope the TSA doesn’t break anything on your way out. Hope customs at the destination doesn’t fuss over anything on the way in.

However, all those issues aside, every other piece of the planning puzzle is falling into place just fine except for one small issue. The flight home is scheduled wheels-up at O-Dark-Hundred in the morning, and there is an opportunity to dive something really, really cool the previous afternoon… late in the afternoon. The question is: Can you do that dive without getting bent like a pretzel on the flight home less than 12 hours later?

The whole issue of Pre-flight Surface Interval (PFSI) is a contentious one. The old-school guidelines were wait 24 hours after diving before jumping on a commercial flight. But that recommendation has been revisited in more recent studies and the PFSI shortened; with suggestions that various other factors such as breathing nitrox, the length of safety stops, gas breathed during safety stops, and the duration and depth of dive, can all influence by just how much the PFSI can be shortened.

A quick straw-poll of my dive buddies tells me that the definitive answer is a moving target. There is little agreement.

What we can take as read is that flying after diving has a strong potential to apply extra decompression stress on a diver and increases their risks of decompression sickness. There seems to be a direct relationship between the risk dropping and the amount of time spent out of the water increases allowing excess inert gas to be eliminated normally and harmlessly through the lungs. Some trials have estimated the PFSI necessary for a low DCS risk (read acceptable number of incidents of DCS) after relatively long single or repetitive no-decompression dive profiles sits between 11 and 16 hours.

The PFSI for dives requiring staged decompression stops, was around 22 hours. At first blush then, a 24-hour break after diving would seem in most sport-diving cases to be very conservative. But then again, what worked in a dry chamber on a couple of hundred test subjects, may not apply to the average dive tourist coming home from a week in paradise where the diving was punctuated with rum, grilled fish and late-night romps on the beach. Equally, it also may not apply to an informed technical diver who pads her/his decompression stops with extra time, and breathes pure oxygen for long periods during that PFSI!

Well worth the download and reading time is: The Influence of bottom time on preflight surface intervals before flying after diving, published by Undersea Hyperb Med. And authored by Vann RD, Pollock NW, Freiberger JJ, Natoli MJ, DeNoble PJ, Pieper CF. (2007). It is available from the ultimate diver’s research tool: http://archive.rubicon-foundation.org/xmlui/handle/123456789/7343.

The study’s conclusion suggests “that bottom time, repetitive diving, and a decompression stop may significantly influence the pre-flight surface intervals required for low DCS risk. Moreover, it highlighted the need for additional human trials to resolve the effects of exercise and immersion on DCS risk during flying after diving. Such information might assist in the calibration of dry, resting trials for the effects of immersion and exercise which would be useful as dry, resting trials are less expensive and faster to conduct because more subjects can be exposed per chamber dive. This might be of aid for improving the accuracy of existing flying after diving guidelines.”

Significant in that conclusion is the call for additional human trials to resolve the effects of exercise and immersion on DCS risk when flying after diving.

I volunteer.

However, I would be far from an average test subject since something seems to put me outside the bell-curve for DCS risk. For example, my experience with PFSI is far from what’s generally acceptable and my practices at times have been foolhardy. Furthermore, I fall outside the age category that most studies could ethically accept in any trial… but all that aside, I would love to be a guinea pig.

 

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.

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.

 

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.

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!

 

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.

AN OPEN LETTER TO NEW DIVERS ABOUT STAYING ALIVE

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

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

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

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

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

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

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

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

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

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

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

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

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

Thanks. Now go dive… in open water.

Steve Lewis
TDI instructor trainer #6

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

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

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

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

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

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

2. Eyes / Vision

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

3. Face (muscles and nerves)

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

4. Hearing

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

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

5. Swallowing Reflex

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

6. Tongue

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

7. Muscle Strength

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

8. Sensory Perception

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

9. Balance and Coordination

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

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

After the exam…

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

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

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

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

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

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

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

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

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

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

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

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

The first is how much backup gas is enough?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Steve Lewis (doppler@techdivertraining.org) is an active instructor-trainer with TDI/SDI and has written scores of articles on dive safety and skills development and is a regular contributor to several online magazines and discussion groups. He occasionally dives “open-circuit with a single aluminum 80” but never without a pony bottle by his side filled with a lean nitrox. His best-selling book called “the Six Skills and Other Discussions” is available at select dive stores and through onLine stores such as Amazon and Create Space eStore via: https://www.createspace.com/3726246.

THE FIVE WAYPOINTS AND SIMPLE ASCENT BEHAVIOR

“You’ll always miss one hundred percent  of the shots you don’t take.”
Wayne Gretzky, the only NHL player to have his number (99) retired across the league – Born January 26, 1961

 

With all the postings recently on the scuba forums asking about deep stops and gradient factors, I figured it might be time to get back to some basics. Let’s talk briefly about the five waypoints and ascent behavior, which is a fancy name for a couple of simple ideas designed to help divers manage decompression stress and get out of the water after a dive with all their fingers and toes in place, and all their faculties intact. For the record, decompression stress is something that affects every diver at the end of every dive regardless of what type of dive went before. That said, I believe that for this discussion, it makes most sense to concentrate on the simplest possible ascent: surfacing from sport dives.

In the hope of getting everyone to sing from the same song sheet, let’s define sport dives as dives that require only one decompression stop (sport diving textbooks call this a Safety Stop), and which are conducted no deeper than the common depth limits set by several of the major sport diving certification agencies: 40 metres or 130 feet.

Now, I have to make a small confession, I teach technical diving and I have been teaching students in my classes about Waypoints and Ascent Behavior for more than 14 years. Learning the basic guidelines behind this stuff is a precursor to getting Deco on the Fly squared away. And I include a little module on that as part of my decompression courses. It is easy to learn, helpful and a good mental exercise for folks who want to conduct dives that are deep or long or both.

But it is MORE important to emphasis that the guidelines controlling ascent behavior are NOT only for technical diving; and the five waypoints, which form the underlying structure on which ascent behavior is built, are shared by ALL dives, even sport ones.

Obviously, most sport divers do not need to be bothered by anything outside the stuff covered in their student workbooks. And you will not find anything about Ascent Behavior, The Five Waypoints or anything similar in any of those. Many sport divers are happy – and well-advised – to strap on a Personal Dive Computer (PDC) and follow its directions. However, some of us like to know more than the suggestion “to follow what your computer tells you to do.” For example, if you were one of those kids who took things apart – like the wall clock that Auntie Jane gave your mom and dad for a wedding present – please read on.

The first step is to understand a basic concept, as true in diving as in anything else: when something looks complicated, we can make it look much less threatening by slicing it up into bite-sized pieces.

OK, once we buy into that, let’s apply its logic to the journey from a dive’s maximum depth (or average depth if you want to be more precise) to the surface. This trip can be punctuated by Five Waypoints. And just to restate an important point, these five waypoints work for ALL recreational dives whether they take place in 100 feet or 100 metres. The only differences are that on an ascent from a deep dive, there will be one or more gas switches (from a mix breathed at depth to a gas designed to optimize off-gassing); and the “safety stop” or single decompression stop that is common and recommended for a sport dive, is replaced by two, three or a whole bunch of staged decompression stops ranging from three minutes to many, many times more. All that said, the five fundamental waypoints remain the same!

These are:

1. Planned Maximum Depth or Actual Average Depth

2. Off-Gassing Ceiling

3. First Running Stop

4. Staged Decompression Stop(s)

5. Surface and Surface Interval Time (an often neglected but important part of all dives)

Most technical divers will probably already have an idea what each waypoint is but let’s have a brief explanation for the sport divers reading this.

Number one is simple: how deep did you go or, if you swum a saw-tooth profile, what was your average depth. The second waypoint is trickier to get your head around, but try this for a start. The off-gassing ceiling is a theoretical point in the water column during a diver’s ascent where the net result of the on-gassing and off-gassing meringue that goes in inside a diver’s body, is that more inert gas is coming out of her body than is going in. In other words, the off-gassing ceiling is the point where decompression and true ascent begins. For sport divers doing sport dives to 40 metres or less, we can ballpark this point at a little less than one and a half bar / ata shallower than the average depth. So for a dive to 40 metres or 130 feet on an EAN30 for example, the off-gassing ceiling (or gas transition point) sits at around 25-27 metres or slightly shallower than 85 feet.

Five Waypoints and Ascent BehaviorThe next waypoint – number three – is the first running stop, and at this level of diving, we can fix this at about one bar / ata above our off-gassing ceiling. Once again this is something that the average sport diver may have an issue understanding. I use the term running stop rather than Deep Stop, because I believe Running Stop better describes what goes on in the water column when a diver switches her behavior (ascent speed) to comply with the guideline. For a sport diver, Running stops are not actual stops but rather a change in ascent speed. At the sport level, this translates to the diver rising through the water column at around three metres or 10 feet per minute. Another way to write this is to put a one-minute stop every three metres from the beginning of the running stops until the safety stop is reached. End result is the same… the diver’s ascent has been checked.

The second to last waypoint is the safety stop. I think everyone knows that this is a staged stop of three to five minutes. All I contend is that this is a staged decompression stop by another name and rather than being optional, should be de-rigueur on any dive involving more than a minute on the bottom. Shallower than 30 metres or 100 feet, and well within the NDL, a three-minute stop is fine, deeper or closer to the NDL, stopping for five-minutes makes more sense in my opinion and experience.

The final waypoint is the surface and the surface interval. The SIT is the final stage in a diver’s little gamble with DCS. It is during this time that our diver has to be aware of any strange messages from her body. And it is during this time that she has to prepare herself for her next adventure. In the final analysis, this stage is as important as the rest of her ascent.

OK, those are the Five Waypoints, now let’s take a quick look at how a diver should behave moving from one waypoint to the next. This article is about Ascent Behavior after all!

Here’s the simple pattern for a sport dive. The diver ascends at nine metres or 30 feet per minute but no slower, between waypoints one and two (depth and off-gassing), and nine metres or 30 feet per minute but no faster between waypoints two and three (from off-gassing to first running stop). The diver then moves at three metres or 10 feet per minute between three and four (running stop and safety stop), and once the safety stop is completed (usually at either six metres or three metres (that’s 20 or 10 feet), she will go slowly to the surface no faster than three metres or ten feet per minute.

This is a variable ascent speed: tricky to master but certainly doable for just about ANY competent diver.

What bears thinking about and certainly bringing to everyone’s attention is that following these guidelines, a diver who has finished conducting a 10-minute dive at 39 metres (a smidgen less than 130 feet) will take around 14 minutes to surface! (See illustration. Apologies for imperial users but the conversion to feet is: 39 m = 129 ft; 26 m = 85 feet; 17 m = 55 feet; 3 m = 10 ft.)

A note for the propeller-heads among us who thrive on the nuts and bolts of deco theory: Following these guidelines makes for a slightly slower ascent than all but the most conservative PDC running a dual-phase algorithm. What is key to making this work is understanding that any time spend below the off-gassing ceiling is adding to bottom-time, and that running stops at this level is just a fancy name for slowing one’s ascent to three metres or 10 feet per minute.

Also important is to realize that decompression theory and the algorithms generated by those theories are not grounded in a perfect science. The maths are exquisite. How closely your body and mine follow the tracks laid down by those mathematics is something else more akin to a crap shoot to quote a decompression expert.

Sure, your brand-new fourth-generation PDC is a thing of beauty, has a gaming console and a CPU more powerful and programming more complex than the computers that helped land Neil Armstrong and Buzz Aldrin on the Sea of Tranquility. But decompression theory is just a stab in the statistical dark, and I believe that having an understanding outside of your PDCs user manual — the Five Waypoints and Ascent Behavior for example — is a useful nugget of knowledge. Dive safe folks.

This essay is based on an article that first appeared in Diving Adventure Magazine in 2006. A version was also used as the basis of a chapter in the Six Skills and other discussions called The Deco Curve: Controlled Ascent Behavior and contingency decompression on the fly.

Cardiac Stress Testing and technical diving

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

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

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

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

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

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

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

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

CCR Cave… special circumstances or a walk in the park?

Following on from one of the main debate streams that surfaced during the NACD conference, a few buddies and I recently discussed the “deliverables” of a CCR Cave Diving course.

One of them — and it seems a valid topic to present to “new” CCR cave divers as well as experienced OC cave divers signed up for a cave orientation course — is gas volume management for bailout scenarios.

Typically, OC cave divers have a pretty simple set of rules to govern how much gas they need to carry with them. For CCR divers, those rules are not as simple because there is an extra variable. And that variable is the diver’s gas consumption rate once he has bailed out: it will vary a lot!

To better understand that why this is, we have to consider the reasons that would drive a CCR diver to abandon “the loop” to breathe open-circuit.

One example — perhaps the worse-case scenario — is carbon dioxide poisoning. There are a bunch of possible events that could lead up to this, but for the time-being, let’s just take it as read that the diver has experienced one almighty pear-shaped CO2 breakthrough event, and has ALMOST left it until too late before bailing out. He is hyperventilating and is close to panic.

So, what consumption rate is best to use as a benchmark?

For most to the OC stuff I teach — and in lieu of real data — a SAC rate of 14 litres per minute is a good starting point. (That’s about half a cubic foot for those struggling with imperial units.) To find the actual consumption (RMV), that number would be multiplied by the depth or average depth expressed in bar and the product of that calculation by a number to represent the Dive Factor (workload, thermal stress, etc.). For most OC dives, a DF of 1.5 to 2 is OK. However, for a CCR diver battling back from the edge of CO2 oblivion, a DF of 3 is the minimum recommended stating point.

To put this into a real-world example, consider a CCR diver bailing out around a 40 minute swim from the mouth of a cave with an average depth of 25 metres.

Our 14 litre per minute consumption rate now gives us 14 X 3.5 (depth in bar) x 3 (DF) X40 (minutes to surface) which equals 5880 litres.

That is a lot of gas, and effectively requires the diver to carry more than two fully-charged 12 litre cylinders (aluminum 80s) as bailout. Is this realistic? Is it realistic to imagine that the elevated consumption rate experienced immediately following CO2 break-through would persist for the full duration of the exit swim? Also, is it wise for the diver to have no redundancy in the event of one of those two bailout regulators malfunctioning?

What do you think?