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Author Archives: doppler
Thoughts about the importance of body position and cave diving.
When we agree to lead a cave dive, we have — in effect — accepted a heightened responsibility. From one perspective — an important one — our job as lead diver is to keep our buddy(ies) safe, focused, aware and informed. In the simplest terms, we've agreed to get everyone to where we want to go, and — far more important — that on the way there, we'll make the best effort possible to lay a breadcrumb trail to point the way back to where we started. And all this "work and responsibility" is so our journey back out of the cave can be completed without a hiccup or hesitation; and without any need for an in-situ debate. In other words, our exit will be clean, without stress, and fun.
Let me start off by saying it is a privilege to be the lead swimming into a cave. Even a dive along a familiar route has something to teach us, and leading any cave dive, even the most straightforward one, can be the greatest learning experience whether you are a newbie or a seasoned cave diver. Also, the lead diver is the one controlling the dive's tempo and — to a great extent — its character.
What an opportunity!
One simple secret to being successful in this role is communication. And since we can't natter to our buddies as we swim, we have to use non-verbal ways to get a message across when we're surrounded by water-filled rocks. Eyes and vision are the best options!
Every cave dive starts with a plan — well, at least it should do — and plans are created on the surface, perhaps with a map spread out on a table, and wetnotes in hand. This is when the route is decided, and this is when waypoints and navigation are discussed. (Other things too are decided, but right now, let's focus on waypoints and navigation.)
So, let's say that I've been designated to lead a team of three open-circuit divers. We have a particular section of the cave in our sights, and the purpose of our visit is to take an "I-love-me-wall" photograph (or perhaps one for a magazine) when we get there.
At some point during the planning process, I will have transferred the basics of our conversations to a page or two in an underwater notebook. That conversation may have been condensed into no more than a simplified stick drawing of the cave's main line with mnemonic notes such as "T-Left, T-Left, T-Right, Second Jump Right." All that's important is that I've created it, shared it with my team, and everyone is agreed that it's correct.
With our dive goal in mind, my team and I will have also worked out how many reels, spools, and navigational markers I need (and they need) for this dive, including how and where each will be deployed.
Great, all straightforward so far; now I just have to do it in the water, during the dive, making sure I get everything in the right place, and at the right time, with fluency and skill. For a relatively experienced and active cave diver, that in itself should be relatively easy, and should be fun; more of a challenge is that my teammates have to SEE me do it, agree with my placements, and understand the consequences of any navigational decisions I make and mark. I also need visual confirmation from them that it's okay to continue. In short, we need to communicate with each other throughout our dive but most definitely when there are decisions to be made and confirmed.
Key to these needs is positioning myself in the cave so that I can:
see the main line and the line in the tunnel we're jumping into (or at least the tunnel itself
See my buddy(ies)
Back-reference where we have been
Scope out where we are headed.
To accomplish all of this, the way I orient myself becomes a critical communications skill. Clearly, the practice of laying in the water, ahead of my companions, facing forwards with the mainline — or whatever I'm working on — immediately in front of me and shielded from everyone else's gaze is unacceptable and it's lazy. Unacceptable because doing so is potentially dangerous. Lazy because with a little effort, we can do it properly.
Take for example if I were too lazy to place a marker at a line T; or if I swam across a gap without my buddy noticing? Or if something similar happened with a set of markers indicating the mid-point between two ends-of-line? Or if I obscured another team's line markers from my buddy, and on the way back, they confused her. (Remember, when we turn our dive to head home, she — my buddy — will be leading.)
These what-ifs may be unlikely, perhaps, but nevertheless possible.
And so, the easy fix is to be aware and present at all times, know exactly what has to be done "right here, right now," and to make a point of positioning myself correctly at every main decision point and to be sure my buddy(ies) can see me (eye contact) and can see exactly what I'm doing.
(By the way, if you have ever asked yourself why your cave instructor insisted you learn helicopter turns and back kick — possibly beating you with a wet-noodle until you got it right — this is why. Precise control of your body position and orientation in a cave is a required skill for anyone going deeper into a cave than the drip line.)
For the record, decision points include, but certainly are not limited to:
Running a primary reel to the main line and installing an attendance marker
Making a planned jump by installing markers and line
Approaching a line T and marking it with a cookie or REM
Passing a jump but not taking it
Passing fixed line arrows indicating distance to end-of line
Passing fixed directional markers indicating an end-of-line different to the intended exit and marking/cancelling them
Passing another team's spool, jump reel, line marker(s) or anything that may be confusing especially in a lights-out/low-vis exit
Dropping or retrieving stage or deco bottles
Any point during the dive where you want confirmation which way is "home"
Correct body positioning is simply a function of fore planning and common sense. Take for example setting a jump. An acceptable procedure for RAID divers is:
Thinking ahead I prepare my line markers and a spool
As we approach the jump, I signal the jump is ahead and get confirmation from my team that they understand what's ahead
At a convenient spot but within reach of the line and close to the marker or markers indicating the jump, I stop and change my orientation in the cave so that I can see the main line in both directions (and "okay" it if need be), I can see my buddy(ies), I can see the end of the jump line into which I'm going to tie my jump spool. (See diagram below.)
The team are going to jump to the left… The lead is correctly oriented to both see and be seen.
I install my cookie indicating the direction of "out" and install a spool or jump reel
I indicate the direction of "out" to my buddies with a hand-signal, and get confirmation
I show them the direction I'm going to swim and when possible the bitter end of the jump line I am tying into
I signal OK, wait for confirmation, and make the jump and install an attendance marker on my line close to my tied-off spool
When the jump line is installed, I move away and orient myself to watch my buddies swim across and inspect the jump spool — confirming it is installed correctly and adding their personal attendance markers
Everyone signals OK, I reorient to the direction of the jump line, and continue the dive.
Of course, different circumstances, and factors such as the size of the passage, the length of the jump, and the size of the team may require a slightly different approach, but what's important — and a key pillar in safe cave diving — is that the lead diver takes the time and makes the effort to include his/her buddy(ies) in the decision-making process and pauses long enough to get confirmation that everything is understood and Okay at EVERY decision point.
All this does take time. On a dive with complex navigation and five or six jumps, making the effort to be a good lead would add eight or ten minutes to the overall length of your dive. Who knows, perhaps more. However, taking the trouble to do things properly may mean the difference between everyone getting out as a team or not.
Yea, it's worthwhile.
Steve Lewis is an avid diver, best-selling author, adventurer and motivational speaker. Among other eclectic pursuits, he is also a RAID Cave instructor-evaluator.
© Steve Lewis, 2019.
Contact training@techdivertraining.org for more information or for permission to republish / share this essay.
Posted in dive-related
HOW CAN I EXPLAIN THE ATTRACTION OF WET ROCKS?
A LOVE LETTER OF SORTS…
Somewhere on the simple, spiral DNA roadmap that each of us has inside every cell in our body is a tiny snippet of code that connects us to the desires of our first human ancestors; and beyond. And somewhere in that snippet is an even smaller piece of ageless programming that yearns to belong to the sky. Secretly, and deeply in our cultural past, we envy the birds, and crave to soar above this beautiful planet and for a short while, escape the relentless pull of gravity.
This lust for flight is hardwired in each of us; it is innate, nobody is immune to it. In a few of us, the appeal, is so strong we are driven to do extraordinary things to satisfy it. I choose to cave dive; and rather than giving into that desire, that hunger for flight, by soaring above the Earth, she allows me to float inside her; deep in her underground rivers; her canyons; her dark spaces. She has shared with me her secrets, and I love her for allowing me to enter into those places, to see her wonders, touch her delicacy, become lost in her beauty.
The principles of diving are simple. Basic physics manifest in weightlessness. Water supports us. With practice, we can hover in the water column without effort. With practice, we can spin, turn, glide, soar, dive, and somersault with a carefully applied and skillful flick of our feet. The cumbersome equipment we require to be comfortable, to see, to navigate, and to breathe in water disappears and we experience a unique freedom. We really can become one with the water; one with the earth. This is a form of worship.
In clear water the overall sensation of this experience is of flight; we are flying. The ocean offers this, but caves are, for me at least, more compelling, and the water in many caves is a clear as Evian water. The sensation of flying is within easy grasp.
The features of a cave — its decorations, its furniture, its rooms, cathedrals, crawl spaces, and sculptured, fractal surfaces, float by. Art. Just art.
So caves are special, and cave diving is a privilege extended to few. It is a small club, and membership can be expensive. Earth is a jealous lover. When she accepts you and allows you inside her, she expects your total respect and monogamy; an odd resentfulness of other mistresses. I have buried too many friends whose lives have been snatched from them for no greater reason than for a brief instant, they forgot to tell her how much she meant to them, they became complacent, they forgot to be gentle with her, and forgot to submit to her vanity and ego; they did not comply to her rules. And she allowed them to perish.
Perhaps all cave-divers are running on borrowed time. I cannot say. I have given in to the Earth's fatal attraction. I have stopped worrying about that; I have been lucky. She allows me to woe her and accepts my devotion. She has guided me, and watched me fly through places no other human has seen. I have hung motionless except for the beating of my heart, loud and persistent in my ears, and looked at scenery veiled in darkness since the beginning of time; a place that has never allowed any other human to look at it. The Earth and cave diving have given me this.
And yes, it is only wet rocks, but to me this scenery is as beautiful as any reef, any wreck — and god knows the temptation to be unfaithful is present in them — however, reefs and wrecks are simply platonic relationships; pleasant dates, a brief press of the lips at the end of our time together. Caves are the object of a deep, visceral, want; a lust; a true love.
And you, my little Barefoot Forest Imp, understand and forgive my infidelity; and for this gracefulness, I adore you too.
Posted in Business of diving, Cave Diving, dive-related, Scuba Diving, tech diving, Technical Diving
How do I get there from here… Step one on the road to Technical Diving
Here's a very simple piece of advice if you're being pressured — by your mates, your instructor, or a little voice inside your head — to sign up for a dive class. BEFORE wasting time and money on another course and its accompanying piece of plastic (or eCard): "GET A PLAN."
Base that plan on what you want out of diving, and how much of your free time — and disposable income you want to dedicate to your plan.
Also, it will help motivate you if you work towards your goal with a buddy who has similar aspirations. Kinda like having a running mate who you can trust to ignore the rain and the wind, and to meet you at o-dark hundred on winter mornings to jog 10 k.
And finally, be realistic with your schedule. You will be doing yourself a disservice piling training sessions one on top of the other. PACE yourself. There's no prize for the one who "finishes" first.
(Well, two things about that: there is no finish, at least none I can see. After more than 20 years teaching technical diving, I'm still learning; Secondly, you will grow more and become a better diver by punctuating your dive trips (read "experience gathering expeditions") with targeted training sessions rather than the other way round. There is certainly no set ratio; everyone is different, but think about starting out by saying for every thousand dollars/pounds/Euros/shiny beads I spend on travel, I'll put 200 in my training fund piggy bank.)
Okay, so here are ten tips to help you get your plan created:
Have a long-term goal in mind. "I wanna dive the Empress of Ireland, the Bianca C, and the MS Mikhail Lermontov; I want to swim the Grand Traverse; I see my future-self on a rebreather at 100 metres taking samples for scientific research; My daughter and I have a trip to Truk Lagoon planned and I wanna be ready, etc." All perfectly valid goals. Write yours down on a piece of paper and stick it on the fridge door.
Create a budget for time and money. Quality training cost money. For many classes with a professional instructor, you should be planning to spend $250 – $350 per person, per day on average. Most classes, complex classes like cave or decompression or basic CCR, can last five or six days. By all means research your choices; get booked with someone you're happy with, but don't skimp on money or time.
BEWARE of any operation/individual guaranteeing you'll get certified. Technical certifications are earned not bought, who knows how you'll do? There are no guarantees you'll pass; but a good instructor will make sure your experience will be money well-spent.
Create a timeline… with waypoint so your progress can be followed. You'll need help with this. Ask advice. Then get a second or third opinion. The answers will tell you a lot about the instructors/operations/dive shops you ask!
Think laterally when searching for help with training (your pathway might take you away from your local dive shop and towards an independent professional, it may take you to the next town or out of the country. So, THINK GLOBAL… it's make you grow.
Ask: Am I ready to have most of what I know about diving, challenged and modified?
Am I willing to travel?
Do I do well with constructive criticism? Technical instructors are trained and conditioned to pick bad habits apart. The process can be unsettling for a student with "issues."
Are you aware that going deeper, staying longer, breathing different gases, swimming in overhead environments all carry more personal risk of injury, death or worse?
And finally, you need to understand and appreciate that some forms of diving are addictive. They will take over your life. Are you ready for that?
Good luck and "Dive Safe!"
Stage-bottle logic
There are different schools of thought about the "best" way to manage gas volume when cave diving with stage bottles.
The so-called traditional method is to treat the gas carried in stages, exactly as the primary gas supply: breathe one-third on the way in; one-third on the way out; and leave one-third for contingencies. If nothing hits the fan on a dive following this method, divers surface with stages, and primary cylinders each about one-third full.
Yet another option is "half + 15." With this method, contingency gas for the stage is carried in the primary cylinders. This method requires a little more thought and arithmetic; but is considered by some to be the most conservative and best method when multi-staging. If everything goes smoothly when employing this method, divers surface with stages close to empty, but with all the contingency gas in their primary cylinders, which — with a single stage — translates into the primaries (twins or sidemount) being around half-full or more.
And finally there's the seat-of-your-pants method which like half + 15, allows around half the volume of the stage bottle to be breathed, but critically, unlike half + 15, does NOT preserve any additional contingency gas in one's primary cylinders. Provided nothing goes awry, divers using this "technique" surface with empty stages and primary cylinders with about one-third remaining. You don't have to have a phD. in risk assessment to realize this is the most "liberal" way to dive stages; if anything dramatic happens, it can mean that divers do not surface at all.
But let's leave discussion on the pros and cons of each method as the topic for a later blog post. Let's focus instead on an error we should avoid when diving with stages in a cave regardless of which gas management rule we follow. That error is dropping a stage immediately its turn pressure has been reached.
It seems to be a more logical, more conservative, and therefore better practice to carry the stage and it's extra gas a little further into the penetration.
Let's look at a couple of disaster scenarios, and see why the habit of carry stage bottles a little deeper tends to be the better option.
Two divers (the ubiquitous Diver A and Diver B) have planned a stage cave dive. For the sake of simplicity, each is using the same size primary cylinders and each has the same sized aluminum stage bottle. Each has identical consumption, and fill pressures in all cylinders are identical. (An unlikely situation, but convenient for our purposes!)
Also, to forego any confusion over bar/litres or PSI/cubic feet, let's consider the starting pressure in the primary bottles as 3P; and in the single stages as 3S. Our divers, A and B opt to dive following the Rule of Thirds in both primary and stage bottles.
OK, scenario one: Our divers begin their dive and, conventionally, breathe from their identical stages to start their dive. After a pressure drop of 1S, they drop their stages… each has 2S of gas remaining .
They swim on breathing primary gas. They each consume 1P of primary gas and signal "turn the dive." At precisely this moment, Murphy joins their dive, and Diver A has a massive problem with his primary gas supply. He signals his buddy, and they share gas. Now Diver A and Diver B are breathing from Diver B's 2P volume of gas.
If things go well — no entanglement, no slowing down because of restrictions, no elevated breathing rates, no taking a wrong turn in the confusion, and no arguments over navigation — they make it back to their stages with zero pressure in Diver B's primary cylinders.
They grab their stages, and spend the rest of their exit thinking about how close a call they just had. They each surface with 1S pressure of gas in their stages, but zero in their primaries.
OK, scenario two is similar: But in this case Diver A and B when they have consumed 1S of the gas in their stages, switch to their primary gas, and opt to carry their stages a five or six minutes, or more, further into the cave before dropping them.
At the same point in the dive — just after the turn — Diver A suffers the same disaster, and has nothing to breathe. So, both exit breathing from Diver B's 2P volume of gas; however, in this case, they reach their stages a few minutes earlier than in scenario one. There is gas in Diver B's primary cylinders when they pick up their stages and continue their exit, during which they give thanks that they carried their stages further into the cave.
They surface with less than 1S of gas in each stage having perfectly justifiably used some of the reserve contingency gas in those stages to exit calmly. Diver B has some gas in her primaries; and, as in scenario one, Diver A's cylinders are still empty.
Now we might argue the likelihood of the type of complete gas loss Diver A suffered in both scenarios one and two as remote… highly rare, probably impossible. But what cannot be disputed is that in scenario two, by carrying their stages for just a few extra minutes during their swim in, they had contingency gas placed in a better place than in scenario one.
We can debate how best to manage contingency gas volumes in stages (there may be benefits to each method), but in most cases it seems a better, more logical option to think before you drop; and wait.
Dive Safe!
Posted in Accident Management and Analysis, Cave Diving, CCR diving, Rebreather Diving, Risk Management, Scuba Diving, tech diving, Technical Diving
Double Arrows… what do they mean exactly?
Cave divers have a secret code… well, according to a non-cave-diving buddy we do. And perhaps she's right; we do have a few odd hand-signals that are specific to cave diving.
What I did not mention to her when explaining the peculiarities of " I'm Stuck," "Changing Second Stages," "Tangled in Line," and "Okay buddy, I'll help yer, but you're gonna owe me…" was that some of the basic signs we take for granted in North America, are not universal in every cave-diving community.
Double arrows indicating proximity to a jump / side passage is a good example. (See the photo below.) Outside of North Florida, this may or may not signal what it does here: time to tie in a jump spool, fix attendance cookies to the gold line, and "Let's go roaming!"
What's perhaps more baffling is that even in the North American cave diving community, there's a general misunderstanding about what exactly is meant by another set of double arrows.
The picture below shows two directional arrows pointing in opposite directions. Similar but with a very significant difference… well different certainly… but how!?
Until recently, I thought it generally accepted that this particular configuration indicated the mid-point between two "Ends of Line." But during the past month, diving various caves but none separated from another by more than a two-hour drive, I heard it referred several times as indicating a "Safe exit in either direction" or "The halfway point between two exits."
While it's a fact that an end of line — a break in the main line — is usually where the overhead has a hole in it and daylight streams into the blackness of the cave proper, that is absolutely NOT the same thing as a safe exit; and the difference is more than a question of semantics, with the potential for a bad day ahead for assuming it is.
So, lets think about why this is.
A cave diving team, unless one of them's clairvoyant, can only be sure of one safe exit: the one they came in by. Everything else is a mystery, and in truth, in a few cases there's no absolute guarantee that when they get back to the hole they came in by, it'll still be passable. Perhaps the only sure bet is large, open caverns like the entrance to Jackson Blue Springs in Jackson County, on Florida's panhandle.
Caves, and especially sinkholes, have a dynamic nature. A sinkhole that a diver could climb in and out of yesterday, may have suffered a mini-landslide overnight making it impassible today. A tree providing shade last week, may have had its root system undercut by yesterday morning's downpour, and is now sitting in the sinkhole like Aunt Zenia's potted aspidistra: short of digging out, there is simply no exit now. A rock may have fallen from the ceiling a few feet from the sinkhole blocking access with an immovable chunk of limestone and 40-million-year-old fossils.
So, that's why it's a little risky to assume the mid-point arrows indicate anything other than equal distance between two ends of the main line, and nothing more… at least that's the case in North Florida.
"Teaching" yourself Situational Awareness (SA)
SA is not easy for an instructor to teach. Since some level of SA is innate for most of us, many instructors opt therefore not to include an SA module in their technical diving programs, preferring to simply "mark" a student's SA as there or not there. Of the instructors who DO include SA in their classes, most do so with an understand that their role is to create a non-threatening, learning environment… she/he facilitates rather than teaches, because, with a little guidance, most students — with direction — do fine once they've been show the value of SA. It's more efficient that way, but hereare some "techniques" I believe may help you (or your students if you teach) become more aware: more clairvoyant.
Awareness — both in water and out of it — is a choice. We have to choose to build awareness of what's happening around us: and how what's happening now can influence what is going to happen next either positively, or what's more important, negatively. So, when we dive — and especially when we dive deep or in tough conditions, or in an overhead — rather than being pushed from moment-to-moment with the flow as it were, and with no idea of what comes next, we can project "current events" into the immediate future. This helps to protect us. With this skill, we can focus on things that matter — threats — and ignore the superficial and unimportant things that have no real importance — things that are simple distractions. Developing this skill takes time, but — with very few exceptions — we are all capable of its mastery. And without exception, developing and refining this skill will make every diver a better diver.
First we have to understand what a baseline is. A baseline is normal activity: noise; motion; actions; a series of things unfolding as they should in an anticipated order; everyday things that signal things are just fine and will stay that way — at least until something changes… and it's that change we need to notice, understand, and be mindful of its implications.
Here's a suggestion: begin in a quiet space… like a park or backyard. Be still and silent. Listen to what's going on around you. If this were the 1970s and we were sitting around burning incense, and a block of Hash, I'd say: "Still your mind." Since it's not; and we're not, let's simply say, Focus on this baseline; it is the norm for that environment AT THAT TIME. Consider anything a threat that is not part of it; any odd noise, movement, circumstance… a dog suddenly barking, for example. Consider anything out of the norm, a potential threat… develop a healthy paranoia!
If possible, have someone introduce non-baseline "threats" — a footfall, a mobile phone alarm, a ball being kicked, a door opening, closing, being locked. Learn the appropriate reaction to each. Practice, practice, practice…
Try the same exercise in a shopping mall… more noise and a different baseline, but a baseline nevertheless.
Building awareness of the environmental baseline will help you to switch focus onto things that carry the potential to derail plans or possibly harm.
Now move your baseline awareness exercises to confined water
The secret of making any progress at all is to be relaxed and to be able to maintain your position in water column with quiet hands and feet. Your "consciousness" has to be directed away from yourself, so if you're constantly fighting for buoyancy and trim, you will not have enough awareness left over to gauge and monitor the baseline!
Once you can focus on the baseline, have a buddy introduce "distractions" (displaying minor simulated problems with gear… letting an unclipped backup regulator hang loose, a fin strap not in position, a mask fogging up, rapid breathing, etc.) Practice these simulated "threats" during skills development dives. Document what is noticed and what is not. Simulate multiple oversights in gear and technique between you and your buddies… errant fin strokes, loss of buoyancy control, failure to respond to hand-signals. Make your debriefs learning exercises.
Enlightened self-interest tells us that a problem with our buddy's gear, his or her piece of mind, lack of skill, is a potential problem for us. That's one of the most important values of good SA!
Most of all, apply what you learn on every "real" dive not just "practice" dives. Try to expand your SA every time you get into the water. I guarantee you'll get more enjoyment — and less threat — out of your diving.
How to get the most from a technical diving program/course
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.
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…
Notice, 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!
Posted in Business of diving, Cave Diving, CCR diving, dive-related, Rebreather Diving, Scuba Diving, tech diving, Technical Diving, underwater Adventures
Tagged learning tech diving
A thought experiment concerning "team bailout" when diving CCR in a cave…
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:
This group did not cave dive together ever again
This group rethought their bailout strategy
This group continued to dive team bailout
Posted in Accident Management and Analysis, Business of diving, Cave Diving, CCR diving, dive-related, Rebreather Diving, Risk Management, Scuba Diving, tech diving, Technical Diving, underwater Adventures
Tagged Cave Diving, Dive planning, Dive Tips, self-assessment, Steve Lewis, Teaching Scuba, team diving, Technical diving
Don't even think about asking for an overfill in your aluminum cylinder…
I don't trust the integrity of aluminum scuba cylinders… at least, not enough to:
overfill any aluminum cylinder (in fact I often under-fill aluminum stages and decompression bottles keeping below the manufacturer's suggestions for working pressure);
keep them in service more than a year or two after their first hydrostatic test cycle (which is every five years where I live);
wander very far from a very conservative approach to the frequency of formal visual inspections, choosing instead to follow the manufacturer's suggestions for cylinders in Heavy Service;
miss Eddy Current testing as part of the VIP procedure (EVEN WITH BRAND NEW CYLINDERS!);
be trusting of loners and rentals, especially those with the look of being in service since, and taking direct hits during, the Gulf War.
My reasons for being a "mother hen" are based on a professional 'cover everybody's arse' strategy to risk management. And a certain knowledge that high-pressure vessels have an enormous potential to harm. I've witnessed the aftermath of two separate aluminum tank failures and have a very strong mental image of the chaos each caused. I read somewhere that the amount of energy stored in a "recreational scuba cylinder," which one can take to mean an aluminum 80, is about the same as two WWII British military hand grenades. A sobering thought.
Of course, one should be equally cautious with steel cylinders, which have a similarly dangerous potential. However, aluminum cylinders more easily carry the scars of mild to moderate abuse in typical everyday service. Couple this with their inherently different reaction to repeated filling and emptying – aluminum's fatigue limit – and the dramatic reduction of an aluminum cylinder's endurance limit from several hundred thousand fills to perhaps hundreds when it is over-filled – and its potential for failure is increased.
Of course, an easy out would be to avoid using aluminum cylinders altogether, but the buoyancy characteristics of aluminum makes 80s and 40s excellent stages, bailout, and decompression bottles. Besides, avoiding their use would be a dramatic over-reaction.
Working within manufacturer's limits and the handling guidelines they supply us, aluminum is safe for many, many more fills than any of us is likely to ask it to endure.
But we do need to be mindful of those limits and guidelines.
Luxfer, the manufacturer of a popular brand of aluminum scuba cylinders of all sizes including the ubiquitous aluminum 80 writes the following about safety and its products… all great advice!
"If the cylinder is used in heavy service then it should be inspected every four months.
"Heavy service" means any one or more of the following:
Cylinders being filled or "topped off" five or more times per week;
Rental cylinders in use during the 'season' and 'off-season' times;
Cylinders used wherever damage is more likely than in normal use or where the
care and/or maintenance is slightly below recommended care.
If the cylinder is known to have had any unusual treatment or condition, it should be immediately visually inspected, prior to its next use.
"Unusual treatment or condition" means if the cylinder:
Dropped, fell, was struck, was in an accident, or when the care and maintenance of the cylinder is obviously poor;
Was stored improperly, and shows signs of damage;
Has obvious corrosion since the last visual inspection;
Has a gouge, dent, scrape, cut, dig or, in any way, has been damaged since the last
visual inspection;
Was stored with water, material or matter inside the cylinder;
Shows signs of exposure to fire or high heat, including any one or more of the
Charring or blistering of the paint or other protective coating;
Melting or charring of the metal;
Distortion of the cylinder and/or any cylinder accessory;
Melting of fuse plugs, valve handwheel, valve protector, and/or any other
valve component or cylinder accessory;
Has been partially or fully repainted or treated to hide damage and/or
fire damage;
Is known or suspected to be leaking; or,
Is known or suspected of having a crack."
Dive Safe… be careful out there.
Posted in Accident Management and Analysis, Business of diving, Cave Diving, CCR diving, dive-related, Rebreather Diving, Risk Management, Scuba Diving, tech diving, Technical Diving
A surprise lesson…
There are plenty of incentives for taking part in a scuba diving 'expedition,' and some of them at least, may not obvious at first sight.
The best, and a motivation with all the enticement of a chocolate-chip cookie in the eyes of the average six-year old, is to learn something new. Coming a very close second – with the pulling power of a chocolate- dipped coconut macaroon in my world – is having a tightly-held, but wrong-headed notion, kicked into the trash, and replacing it with an idea backed by science, logic, and responsibly collected data. Again, a learning experience.
Earlier this year, Jill Heinerth and I were asked to put together a small expedition to do some work in the Bell Island Iron Ore Mine, in Conception Bay, Newfoundland. We had both been there before, and we were both huge fans of what the place has to offer: essentially, the chance to experience truly unique dives in an environment that screams history and heritage.
There were tonnes of other reasons to sign on for this particular expedition, but diving in what is essentially an underwater museum, was pretty high on the list.
A total surprise – and an unexpected bonus – was having my opinion about heated vests and their potential role in diver safety – specifically decompression stress – turned around about 180 degrees.
The lesson went something like this.
Dr. Neal W. Pollock was part of the Bell Island project, gathering data for his research at Divers Alert Network. Neal is research director there – at DAN – and a senior research associate at the Center for Hyperbaric Medicine and Environmental Physiology at Duke University Medical Centre. And when not pushing an ultrasonic transducer against your rib cage, he's a handy guy to have around when the chatter turns to many things related to technical diving.
I'd seen Neal's presentation on Thermal Physiology and Protection at Rebreather Forum 3.0, in Florida a few years before. But, frankly did not really grasp his message. Then, sprawled on the floor of the Bell Island Museum and watching a whole stream of gas bubbles race around in my heart after a dive, helped me – and others on the expedition – listen a little harder to what he was telling us.
A link to his presentation at RB 3 is at the bottom of this page, and if you dive at all, you'd do well to watch it, but the Coles Notes version is this.
If, like me, you figure the safest way to dive is to be warm throughout, you may want to rethink your approach.
Dr. Pollock, suggests that there are three issues to think about when we consider thermal protection. Number one, at depth we must be able to function; secondly, we must take into account the effect of temperature on our decompression stress; and lastly we need to consider comfort.
Based on a "small but significant" study conducted by the Navy Experimental Diving Unit, Dr. Pollock explained: "Divers tend to put the emphasis on the wrong thing… comfort." And comfort, according to the data, and Dr. Pollock, "should only be a distant third."
The NEDU study found that the fewest instances of DCS occurred in divers who started cold, and finished warm. Probably the exact opposite of what happens on a significant number of technical dives. Worth noting is that for this study, subjects wore no thermal protection and worked in water at 36 degrees (warm), and 27 degrees (cold).
Significant also was that there were zero cases of DCS in 80 "cold start, warm end" dives, but in warm/cold dives, probably the situation for many long dives, seven out of 32 (22 percent) resulted in DCS. The dive profile incidentally was a seemingly benign 120 fsw with 30 minutes of bottom time and 91 minutes of deco!
When the dive profile was appreciably altered to be more aggressive – 120 fsw for 70 minutes of bottom time but with an unchanged 91 minutes of deco – the results had very similar implications: cold/warm dives resulted in 0.1 percent DCS.
Of interest to those of us who own and use heated drysuit under garments, warm/warm dives following the same profile, returned a 17 percent instance of DCS (four cases in 24 dives).
A slide from Dr. Neal Pollock's presentation
For technical divers, there are many, many factors with a role to play in decompression stress, but consider this. With a heated vest, several things might happen. The vest is turned on and keeps you warm throughout your dive. The vest is turned on to start the dive, and then is turned off or runs out of power at the end of the dive. The vest is turned off to begin the dive and left off when you start to get chilled as bottom time passes, and only turned on during the latter stages of decompression (probably NOT the most common practice).
Based on the NEDU study, each has possible consequences, and not all of them positive. It would seem that the best option in terms of thermal status, is to start cold and end warm.
As Neal remarked, the NEDU study was across a very small population (73 divers), and one has to take that into consideration when assessing its value and relevance. However, my personal observation of what was happening in my heart after a 90-minute warm/warm dive – thanks to the transthoracic echocardiogram being orchestrated by Dr. Pollock about 20 minutes after I surfaced – is that I won't do that again.
View Neal's RB3 presentation here… and in addition to a much more complete interpretation of the NEDU study, he covers several other related and significant issues… watch it.
https://www.youtube.com/watch?v=yixnr07AiTI
Fixing a lack of skill with complex gear… Nah, try a swimming pool!
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.
A rare honor for a dear friend
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
Posted in Business of diving, Rebreather Diving, underwater Adventures
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.
Updates on Mine Quest Expedition
During the lead in to, and during the expedition itself, I'll be making regular postings about what's going on at my website rather than here.
To follow developments, please follow the link to techdivertraining.org
Mine Quest 2.0
Winter in Newfoundland can be bleak and is most definitely cold, but this week, a group of volunteers and Bell Island Heritage Society staff ignored the weather and did a huge amount of setup work getting things ready for Mine Quest 2.0.
As well as building a platform/staging area for the exploration team to work from, during mid-February's expedition, they carried several hundred kilos of materials more than 225 metres down a ten-degree incline from the surface to the water's edge. Before the building commenced, using pickaxes and shovels to clear away loose rocks from the roof and walls of the mine shaft, then installed temporary lighting.
After the clean-up… the mine shaft we will be working from
Eventually, it's hoped the mine on Bell Island will feature permanent infrastructure that will add dive adventure tourism at the historic site to the world-class wreck diving found just off the island's coast. For the time-being, the hard work will help simplify, and aid the success of an effort to add the the two kilometers of passage explored and lined during the 2007 project I was lucky enough to be part of.
Over the next several weeks, and certainly during Expedition Week (February 13 – 20), I'll try to keep you up-to-date on progress and exactly what's planned.
In the meantime, hats off to Mark ( Magoo) McGowan, John ( Johnny O) Olivero, Nick Dawe, Kyle Morgan, Rick Stanley, Ron Reid, Teresita ( Teddy) McCarthy, Des McCarthy, and Tom Spracklin.
Thank you for your efforts folks.
For a comprehensive line-up of who will be working on the project, visit my friend and co-leader's blog… Thanks Jill.
http://www.intotheplanet.com/newfoundland/
Tagged Bell Island Mine, Dive Tips, Scuba Diving, Technical diving
Building the odds in favor of a good outcome…
A simple tip from the closest thing you'll find to an expert
I have one of the best jobs imaginable… I get to dive for a living. It has drawbacks just like any job… I spend a lot of time away from home and the people I love; sometimes I am compelled to jump into the water when all I really want to do is sit on my arse and veg out; and there are few constants in a very fluid and organic field of research about diving, which means lots of reading, lots of lectures, lots of changes in what we teach and what we reject.
However, there are also a bunch of positives… including the list of things on the drawback list: I travel, I dive a lot, I get to feed my brain new stuff all the time.
One of the best things though is the people I meet. The so-called technical diving community is packed with cool folks. These are the men and women with open minds, boundless curiosity, and a willingness to share what they've discovered. They are stellar human beings and it's a gas to hang out with them, and learn from them.
One guy who always has something interesting to say is Dr. Neal Pollock. Neal is ex-pat Canadian scientist. He's a research physiologist working in the States, and has a background in zoology, exercise physiology and environmental physiology. He is also a diver and part of his research relates to decompression stress.
He also has a very "English" sense of understated humor in his writing and presentation style which appeals to me. I particularly appreciate lines such as: "The approximation of decompression status predicted by current deterministic algorithms should not be confused with 'truth.'" Honest, insightful, and funny.
Anyhow, his latest blog is a hugely interesting read. It's entitled "Flexible Control of Decompression Stress" and you'll find it here: https://www.shearwater.com/news/flexible-control-of-decompression-stress/
Take the time to visit and read. You'll learn something.
Tagged decompression stress, neal pollack, variable gradient factors
Surviving the Rottweilers
Seven 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.
Posted in Accident Management and Analysis, Business of diving, dive-related, Risk Management, Scuba Diving, underwater Adventures
Adventure Tourism "Under the Bell"
Diving 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).
Posted in Business of diving, Cave Diving, dive-related, Scuba Diving, tech diving, Technical Diving, underwater Adventures
Tagged Bell Island Mine, Joe Steffen, Mine diving, Newfoundland diving, Steve Lewis, Technical diving
Gradient Factors… a simplified primer
This short article is based on a series of presentations made in various locations during the late winter and spring of 2015, and is a shortened version of a more detailed treatment to be included in an upcoming book.
Let's start off with a disclaimer and an outline of some assumptions made while working on this blog post.
First off, I did not start out intending to write a definitive piece on decompression theory or on the stellar work of Professor Albert Bühlmann. Also, this contains no detailed explanation of the internal workings of the maths behind a decompression algorithm and the challenges it meets while trying to model human physiology. Simply put, this was written to help the average punter better understand what gradient factors describe; and the potential impact of playing around with the GF settings on your personal dive computer (for example, a Shearwater Petrel).
Secondly, I've made several assumptions… not the least of which is that readers have a basic understanding what happens to an individual after spending more than a couple of minutes sub-surface breathing compressed gas. (That's just another way of saying that I'm writing for certified and reasonably experienced divers who understand that diving can result in decompression stress of one flavor or another.)
OK, that settled, here we go.
All dives are decompression dives, ergo all divers are decompression divers. Our acknowledgement of this and the depth of that acknowledgement can greatly influence our behavior when we dive: most specifically, our ascent behavior. How deep we dive, what gases we breathe, and how long we spend at depth vary considerably from dive to dive; but all dives share one common threat for individual divers: the risk of getting bent.
Smart divers consider many factors when planning dives, many of which help to alleviate that risk. One is choosing to dive a "conservative profile." I guess there are many interpretations of what that means… but for our purposes here, it means choosing a decompression algorithm that's proven, and choosing a setting for that algorithm that will generate stress-tolerant dive tables.
Many PDC (personal dive computers) use a Bühlmann ZHL-8 or ZHL-16 algorithm to model decompression stress in divers and their decompression obligation on ascent. In a way this is odd because both deco models are not only dated (Herr Doktor Professor Bühlmann died of heart failure in early 1994), but are based on the faulty premise that we can prevent bubbles from forming in our bodies during our ascent if we follow the schedules the algorithm kicks out.
The data set on all recreational diving, but in particular staged decompression diving, has grown considerably since the Professor's unfortunate and untimely death, and we now have considerable evidence that in fact bubbles do form even after the most benign sport dives conducted well inside the boundaries suggested by Bühlmann's tables. Some newer decompression models make the assumption that bubbles do form in a diver's body during ascent and make adjustments to the maths which are intended to control their growth and propagation. Many divers believe bubble models better predict what goes on in a diver's body and are therefore, safer. VPM and RGBM are examples of "bubble models." Versions of both are available for use in PDCs.
Yet Bühlmann tables remain popular. They are in fact perfectly functional, and are helping to keep tens of thousands of divers safe from the bends every week. The secret is that with very simple tweaking, a Bühlmann schedule can be made to follow a time-and-place curve very similar to those produced by bubble models slowing ascent and beginning staged stops deeper in the water column.
OK, a little very simple nuts and bolts discussion.
Traditional decompression algorithms – Bühlmann's included – attempt to model what happens in a diver's body using a number of different calculations each representing a different "theoretical tissue group:" and each filling up with and emptying inert-gas at different speeds. Important to note that these tissue groups are mathematical constructs and are not directly related to any actual body tissue such as blood, bone, muscle or brain. Those tissues – in fact all the tissues in a human body – are far too complex in their architecture, component makeup and construction to fit into any of the algorithm's simplified tissue categories. The human body is a mass of variables that defy the constraints of pure maths. So, individual "tissue groups" don't relate to a specific body part, but are a series of mathematical calculations which as a whole attempt to track inert gas uptake and elimination in vivo.
In Bühlmann's ZHL-16 algorithm the fastest group has a four-minute halftime, the slowest (the 16th in this particular series) has a 635-minute halftime. Since we can regard a tissue group as saturated after six halftimes (standard science stuff), the fastest group will be "full" in 24 minutes, while the slowest takes 63 hours and 30 minutes to reach the same state! For the record, the halftimes or the 14 other groups in the ZHL-16 algorithm are: 8, 12.5, 18.5, 27, 38.3, 54.3, 77, 109, 146, 187, 239, 305, 390, and 498 minutes.)
Clearly, Now that we have some concept of the relationship between variable times and various group saturations, let's look at M-values.
In the Bühlmann algorithm, each theoretical tissue group has a maximum internal pressure it can withstand. This pressure is exerted by dissolved inert gas and as long as the maximum is not exceeded, the gas stays in solution, and no bubbles form… well, in theory.
Like Robert Workman before him, Bühlmann termed this maximum internal pressure, its M-Value. Workman had coined the phrase while researching decompression for the U.S. Navy in the 1960s. His M-Value calculations were based on dives done at sea-level… perfectly predictable for Navy work. Bühlmann's modifications took into account attitude and are slightly more conservative. Like a tissue group, an M-Value is mathematics and not physiology, and it is used to track how close a particular tissue group has become to super-saturation (critical bubbling). When a tissue group reaches 100 percent of its M-Value, the likelihood of decompression stress is statistically high.
And finally, gradient factors.
One can think of gradient factors (GF) as a way of adjusting the decompression algorithm to suit our needs, and GF can range between 0 and 100 percent. One hundred percent is the point where M-Value is on the verge of critical bubbling (1), and zero percent is the same as ambient pressure (M-Value of 0 where there is no force driving gas out of solution at all). Therefore, effective decompression can be found somewhere between those two points.
When one uses GFs to set the "conservatism" for one's decompression, one uses two numbers: these represent the Low Gradient Factor and the High Gradient Factor.
In simply terms, the Low Gradient Factor (LGF) defines how deeply in the water column one takes one's first decompression stop. The High Gradient Factor (HGF) defines how close to the 100 percent M-Value one surfaces with at the end of the dive.
Obviously we need to set up some gradient to begin the process of off-gassing (decompression). The slope of that gradient – how much pressure we allow – is a matter of personal faith, comfort and willingness to act as a guinea pig. This is the LGF and one option that seems to have been adopted by many divers – and incidentally recommended by Dr. Neal Pollock from DAN – is 30%.
This setting promotes off-gassing but stops one's ascent deep in the water column but above the gas transition point (the theoretical spot on the water column at which more gas is eliminated than is taken up according to the algorithm).
Setting the HGF is a question of how close to the 100 percent M-Value limit we are willing to venture. Many divers recommend and use 80 percent. Again, Dr. Pollock's suggestion is lower: 70 percent.
Therefore a 30/70 setting is considered by some, including me, to be an acceptable default GF setting.
However, before forming a rigid interpretation of GFs: just as different speed limits are applied to different road conditions, different GFs may be more appropriate for different dives. A 30/70 may work for trimix dives to 60 metres but may be unnecessary conservative for a short warm-water dive to 18-metres… and not sufficiently conservative for deeper dives.
The message then is to experiment with Variable Gradient Factors when planning your dives. Run what-if scenarios… Take notes… Alternatively, read what people are doing and what organizations such as DAN suggest
Most of all, be aware, nobody and no organization can predict precisely the outcome of any dive!
Factors in deep scuba diving
A recent tragic event – the death of Guy Garman attempting a 1,200 foot dive on open-circuit scuba – have refocused the spotlight of community interest on a number of issues specific to deep bounce dives. Or rather, it has engendered a bunch of questions from the diving community at large asking: what went wrong?
In his personal blog, Andy Davis has made a good attempt at answering some specifics relating to "Human Factors" and their possible role in Garman's fatal last dive, but, and without wanting to comment on the specifics of Garman's episode, here is a list some of the other potential pratfalls that await any future record attempts.
Oh, and let's ignore the vagaries of decompression… actually coming back from depth, which is a huge challenge in itself… and look at only the first magnitude of challenges that a diver would face at extreme depth.
First, the issue with breathing helium below a couple hundred meters. One might say that high-pressure-neurological-syndrome (HPNS) is to diving deep on helium what nitrogen is to deep diving on air. But rather than the classic symptoms and signs of inert-gas narcosis (slowing of brain function and stupor), HPNS manifests itself in myoclonic jerks (brief, shock-like seizures of a muscle or a group of muscles), dizziness, nausea, and vomiting… and eventually, coma and death. In effect, HPNS seems to be caused by an elevation of brain function… in lay-person's terms that paint a mind-picture most of us can appreciate, HPNS results in the diver's nervous system short-circuiting.
The depth at which HPNS develops and the severity of its signs and symptoms is more closely related to the rate of compression rather than the depth or helium partial-pressure being breathed. So in essence, the faster one drops in the water column, the shallower symptoms occur and the more severe they are. I was taught the helium depth for potential HPNS on bounce dives is a low as 17 bar/ata. And that, depending on the proportions of the mix, and whether it's heliox or trimix, can become a factor as "shallow" as 180 metres.
As recreational divers push depth limits more, HPNS definitely becomes a rising factor. Commercial, military and scientific divers have learned how to mitigate its risks. In many cases, they take several hours to descend, which lessens the effects of HPNS. Record-depth divers venture to potentially problematic depths and beyond in minutes. No amount of practice, special diets, exercise, yoga, or magic chanting will reliably change basic human physiology. Thinking that you can ignore this fact is like venturing into outer-space dressed in a Star Wars Halloween costume from Walmart and expecting a good outcome.
Getting the right mix is also hugely problematic. Partial-pressure blending is an inexact science… actually, partial-pressure blending as practiced by most divers and dive shops is about as far from science as driving a moped is from MotoGP, but it is commonly done. I do it, you probably do it, my mates do it. With controlled and best-practice procedures, it is a workable fudge for most technical and sport dives. However, for deep dives, the standard methodology used by dive shops and the vast majority of technical instructors offers an unacceptable degree of slop. It is simply too inaccurate. Even the units of measurement we use are garbled, have nothing to do with real gas laws and behavior, and are miss-matched to our purpose. Therefore the margin for error falls far outside the bell-curve of tolerable risk management.
Essentially, when the fraction of oxygen in a breathing gas is as low as it must be for extremely deep diving, laboratory-grade calibration gases should be used to "zero-out" high-resolution oxygen analyzers. Even better is to have certified breathing gases supplied by a gas blending operation, and then verify its contents with a high-res analyzer. Using the standard gear that most technical divers and dive shops use is either suicidal or criminally negligent. The boundaries separating breathable, hypoxic and hyperoxic are simply too close in deep diving for anyone to wing it.
As if that were not reason enough to call in sick on dive day, there is the compounding problem of gas contamination: carbon monoxide, volatile organic compounds, oil vapor, et al. In sport and many technical diving applications, trace amounts of these categories of contaminants may not kill a diver. They may not effect a diver's health at all. However, at depths where the ambient pressure approaches and exceeds 20 bars (190 metres or about 630 feet), even a gas containing a few parts per million, can be toxic. Several manufacturers have excellent equipment to detect these types of contaminants, but this equipment is cost-prohibitive for dive operations focused on recreational dives… even technical ones. Few if any have access to it.
Then there's gas volume. Open-circuit scuba is the best technology for a host of jobs, but diving to extreme depth is not one of them. It simply requires too many tanks, and too many regulator switches. Too many opportunities for malfunctions, mix-ups, missed swops.
For example, let us consider a diver who consumes 14 litres of gas per minute on the surface (about half a cubic foot and a good average for this example). This diver would consume at least 450 litres (that's about 16 cubic feet) per minute at a depth of 300 metres or around 950 feet… and that is if he or she were NOT stressed. They would also need to be adding gas to whatever buoyancy device they had concocted to support multiple tanks… a challenge in itself.
Couple this with the sobering fact that the pressure at this depth is around 31 bar/ata, so even regulators specifically set-up for deep diving, would be struggling to deliver gas at all since that gas would have more than 30 times its surface density at depth. Even a blend with lots of helium would require the diver to work hard just to breathe. And of course, a high work of breathing increases carbon dioxide buildup, which results in a cascade of unpleasantness… including an increase respiration rate and increased susceptibility to inert gas narcosis.
Thermal stress is another factor at even moderate depths both in fresh and salt water. More so in temperate water but in a tropical locations too, the difference in ambient temperature between the surface and target depth can be 20 – 30 degrees Celsius or more depending on current, season, time of year, etc. Combine this with the effects of pressure on neoprene, and it quickly becomes apparent that no standard wetsuit can provide adequate protection to keep a diver alert and functioning optimally below recreational (sport or technical diving) depths.
Well, I am sure these and other "long-shot" interferences such as compression arthralgia, immersion pulmonary edema, isobaric counter-diffusion were all considered by Guy Garman and his team of experts, but for the rest of us, they seem to suggest strongly that extreme deep diving on scuba is a crap shoot with the odds in favor of the house. Don't try it at home kids.
To read Andy Davis blog, visit: http://scubatechphilippines.com/scuba_blog/guy-garman-world-depth-record-fatal-dive/
To read more about HPNS, visit Dr. David Sawatzky's article for Diver Magazine: http://divermag.com/high-pressure-neurological-syndrome
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.
Posted in Business of diving, Cave Diving, CCR diving, dive-related, Rebreather Diving, Risk Management, Scuba Diving, tech diving, Technical Diving, underwater Adventures
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.
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 dive… usually 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.
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.
Tagged Dive planning, Dive Tips, Risk Management
CCR Incident (Feb 2013) – Double Cell Failure, Human Factors – Inquest Report
Totally excellent article on the dramatic influences human factors can have on our behavior… both in and out of the water.
Cognitas Incident Research & Management
An instructor was teaching two students an advanced trimix CCR class. Unfortunately due to two of the cells being current limited and the voting logic voting out the 'good cell', and the instructor being a victim to a number of powerful human factor biases, they had an oxygen toxicity seizure at depth. One of this buddies took the diver to the surface but never recovered.
This incident happened in February 2013 and was widely reported in the (social) media at the time, especially as it quickly became known that the diver was using cells which were 40 months old (cells 1 & 3) and 17 months old (cell 2) and a significant amount of negative criticism raised, primarily how could someone so experienced undertake such a 'stupid' activity, using cells well past their use-by date. Immediately afterwards, AP issued a warning about using out-of-date cells.
Unfortunately a number of technical and…