Triggers of Dive Accidents

[Ken Kurtis]

From what I can relate to as a diver with less the 20 dives is that, there is a lot of multi-tasking with unfamiliar equipment, in an unnatural environment (for humans) in a position (horizontal) that human beings don't spend much time in. 1.Looking at gauges with lots of changing numbers, 2. Buoyancy control (inflate deflate), 3.Location/Navigation, 4. Buddy location, 5. The reason we are there looking at the sea life. For some (me included) it's a lot to take in and keep track of. I'm sure with time all of this becomes 2nd nature.

Excellent observation and comment. The other thing to take into account would be to look at all the OOAs and break them down by experience level. (Disclaimer: It's usually info we don't always get.) But that would give us some idea as to whether this is happening across the board, to newer divers, experienced divers who get more complacent, solo divers, etc.

- Ken

 

[spoolin01]

You might be surprised. SPGs are notoriously inaccurate ... I own 11 of them and can tell you ... because I've done this exercise ... that I can put them all on the same tank and measure a 300 psi variance on the low end of the scale (i.e. high reading 500 psi, low reading 200 psi). This inherent inaccuracy is one reason for the 500 psi rule of thumb in the first place.

This is true, nevertheless as a first approximation to the challenge, true 0 psi is plenty of air to safely surface from 15', as a matter of mundane human accomplishment. That was my point. That some are more challenged by this and that training may strive first to lose no one doesn't change the fact that at some point (soon?), virtually all divers will have the luxury of entertaining other considerations, and likely find this one to be among the easiest to adaptively manage.

Again, you might be surprised. Stress does interesting things to people's thought process ... particularly when they find themselves in a situation they're not sufficiently practiced to deal with. I know of cases of divers who make it to the surface OOA and end up drowning, because it never occurs to them to drop their weights ... or that they have an option of manually inflating their BCDs. One of those cases was a former member of ScubaBoard, in fact.

There're a thousand ways to die, most of them aren't new object lessons for most people. Not that this shouldn't bear on training curriculum, as you point out.

You can define anything in whatever way you please. My insights are based on working with new divers regularly, helping them remediate what I consider inadequate training for diving in local conditions ... and it's given me an insight into how new divers tend to deal with certain situations. That experience has led me to conclude that, given the choice between skipping a safety stop and risking an OOA ... even at shallow depths ... the safest option is to make a controlled ascent to the surface as expeditiously as possible

Of course, as in all things scuba, it always boils down to the specific situation ... but for new divers, rules of thumb are intended to give them a decision path that they can follow when stressed, and to do so in a way that provides the highest probability for a happy outcome.

 

[spoolin01]

There's a big informal epidemiological study that has been going on with divers for decades, and there's no evidence that divers who did what we'd consider to be rapid ascents on a routine basis had sufficient damage to affect their lives.

I'd be interested in a pointer to this study, if you have any more info. Googling brings up too much stuff to wade through, including small studies that appear to contradict your assertion and indifference.

 

[boulderjohn]

I'd be interested in a pointer to this study, if you have any more info. Googling brings up too much stuff to wade through, including small studies that appear to contradict your assertion and indifference.

I don't believe that he is talking about a formal, published study but rather to the fact that millions of dives have been performed following a certain protocol with known results. It is like saying that although there are no formal studies proving it, the fact that millions of people swim in public swimming pools every year without contracting tuberculosis is a good indication that swimming in public pools does not cause tuberculosis. Millions of people doing something with almost no indication of risk would constitute a large study, even if it was not done with someone with a white lab coat in attendance.

 

[danvolker]

DanV - I appreciate that you continue to indulge this discussion civilly (mostly). I'm trying to do the same, though Lamont is tempting me :mooner:. I pounced on your original comment to the new diver mostly for its vehement certitude, in light of my take on the situation he brought up. I hope at least we can agree that in weighing risks and responses, one protocol does not fit all divers, even new ones. You've defended your thinking, I just don't agree that the anecdotes and observations you cite have more than passing bearing on the issue of the health consequences of chronic absorbed gas exposure from NDL diving. Some life-long smokers/drinkers/etc. live to a ripe old age, and many don't show extreme overt signs either, until autopsy. What you do with the information is another thing, but the fact of physical change from chronic exposure to those substances is proven. Apparently there is evidence of tissue damage in recreational divers, and the dimensions of the syndrome are only partly explored. You may have made up your mind about that, my point was that a dead-ended absolutism forecloses them from that opportunity themselves. I'm not talking about the dictates of limited bandwidth during formal instruction, this is not that.

One thing the WKPP discovered/proved, was that individuals with very high VO2 max scores ( from elite level cardio sports) had much higher rates of perfusion ..as a result of peripherol adaptations to training....while in gassing could be said to be more rapid in these individuals, offgassing was far more rapid, and an entirely new set of tables was created ( George Irvine, Bill Mee, Jarrod Jablonski, Dr Bill Hamilton) to allow indivualized tables for highly fit divers doing extreme exposures...

You might consider that an enormous safety benefit could accrue to you and those you care about, if a priority is given to obtaining elite level cardiovascular fitness.
Not only would your ability to offgas be enhanced, but the recovery potential of an extremely fit diver will be higher than an unfit one--degree of inflamation response, and your ability to quickly recover from this. You could certainly relate this to the studies on recreational diver populations where you believe some tissue damage was evident.....there would be two entirely separate populations, with entirely different effects on their tissues.... However, based on the very large number of recreational divers in the 1960's, 70's and 80's that did not suffer a horrific, diving induced infirmity in their golden years, any correlation you find in autopsies is "functionally irrelevant"...if no health complications were known of, and no lifestyle modifications forced on them, then the enjoyment of the diving lifestyle is going to trump your tiny tissue anomalies.



I still think you should read the DIR link of the article on George and the WKPP decompression strategies. You should enjoy the level of science acheived, WHERE ideas were tested with hundreds of man hours, reshaped, made better, retested, and so on until the achievements of today....over 4 mile long penetrations at depths around 280 feet, with run times over 6 hours....decos from 12 to 17 hours where Navy tables would have you at multiple days, doing mass deco from your deco.....

The deep science for this can be discussed....I could get Bill Mee to answer some good questions by email, and I could post here....

Let me know.

Regards,
DanV

 

[Scott L]

Dan, you really know how to motivate a guy to get back into shape.

 

[danvolker]

Dan, you really know how to motivate a guy to get back into shape.

The reality is that fitness is probably the hardest thing for most divers to change ( to the level where a big return can be realized in diving) ...When I did most of my tech diving, I was also a bike racer, and between that, the gym and a few other sports, my body fat never climed above 11%, and was often around 9 or 10. Nowdays, I am training way harder ( perceived effort) than I ever did in the 80's or 90's, but I am having a hard time getting my bodyfat levels below 15 %... I would want to be closer to 12% or below to do the big dives I used to do, the way I used to do them.....I am still working on it....5 to 6 days per week on bike, 25 to 35 miles each day, structured rides each day ( ATP sprint day/interval day/aerobic zone 2 day/easy day/ aerobic day with a couple of jumps, and then the Saturday simulated race day with the big pack on A1A Diet is hugely important, maybe far bigger than the structure, but so far it is a slow road to get back to where I want to be....Maybe in another 4 months....

Where I am, I think I am still way out of the normal recreational population, as far as aerobic fitness and diving physiology is concerned, and and I can tell I am still a very fast off-gasser....I used to do the same exact decos George did on our dives like the RB Johnson and other 280 to 300 foot stuff...right now, those same profiles might still work, but I'd feel alot smarter doing them after I get back to 12% or below....


For Spoolin, if he is concerned about bubble damage, then he needs to start doing race level training on the bike....and, if he wants even more "safety", he should dive with a 20 cu ft bottle of O2 slung DIR style, and after each 60 for 55, or 80 for 15, or whatever the he** he is doing, he could then suck oxygen at 20 feet for 12 minutes.... and get a massive reduction in the bubble damage that he is so concerned about. Relatively speaking, the 3 minute safety stop is just pissing in the wind, if you are as serious as Spoolin about having a perfect autopsy some day

Regards,
DanV

 

[Scott L]

The reality is that fitness is probably the hardest thing for most divers to change ( to the level where a big return can be realized in diving) ...When I did most of my tech diving, I was also a bike racer, and between that, the gym and a few other sports, my body fat never climed above 11%, and was often around 9 or 10. Nowdays, I am training way harder ( perceived effort) than I ever did in the 80's or 90's, but I am having a hard time getting my bodyfat levels below 15 %... I would want to be closer to 12% or below to do the big dives I used to do, the way I used to do them.....I am still working on it....5 to 6 days per week on bike, 25 to 35 miles each day, structured rides each day ( ATP sprint day/interval day/aerobic zone 2 day/easy day/ aerobic day with a couple of jumps, and then the Saturday simulated race day with the big pack on A1A Diet is hugely important, maybe far bigger than the structure, but so far it is a slow road to get back to where I want to be....Maybe in another 4 months....

I am also battling back into some semblance of former top-shape. I believe I stumbled upon a descendant of Dr. Joseph Mengele as my new trainer.

 

[Diver0001]

Ken and Diver0001 -- I, for one, did not take Ken's original post as a "proposal" for a change in training as opposed to a thought experiment as to "What would we (instructors) need to change IF we didn't teach OOA procedures -- that we 'make stupid hurt.'" And I, for one, merely took it as a thought (what if) experiment. [Ken, if you meant it to be, in fact, considered in reality, hmmmm.]

that's how I took it too, Peter. I guess that didn't come across.

because it elequently states my own belief. And the essence of how brilliant someone may be is how much they agree with me!

Hear you there! LOL

R..

 

[spoolin01]

I don't believe that he is talking about a formal, published study but rather to the fact that millions of dives have been performed following a certain protocol with known results. It is like saying that although there are no formal studies proving it, the fact that millions of people swim in public swimming pools every year without contracting tuberculosis is a good indication that swimming in public pools does not cause tuberculosis. Millions of people doing something with almost no indication of risk would constitute a large study, even if it was not done with someone with a white lab coat in attendance.

We were talking about epidemiological studies of sub-acute effects, not anecdotes about who dies or gets plainly crippled. Tuberculosis is tested for and tracked, a key distinction one would think you would get. If sub-acute DCS is not being looked for, then there's no data and you're just guessing and hoping. There's a reason the only studies worth listening to are done with white coats in attendance.