Diver dies on 60m deep air dive

[Bob DBF]

A frequent buddy is my recently certified 14 yo daughter, and I have to admit that I approach diving with her not as a buddy dive but as a solo dive as well, I assume she will need my help but won't be able to provide me assistance, until she is a bit more experienced.

Just because ones buddy is not an equal partner, does not mean you are a solo diver. As a matter of fact the buddy system is more important, especially to the less skilled. As a solo diver one would swim away from a crowd.

As for her not being able to help, you may find yourself supprised. Of course that would depend on the quality of her training.


Bob

 

[mafi]

I had never noticed the increased gas density issue before on deep air dives so I watched out for it on last nights dive. Still didn't notice it even though I was looking for it. St. Lawrence river, 160 feet, occasionally swimming against ~2knot current in full tech gear with 2 stages.

I think, just like almost everything else in diving, it can be an issue for some but not for others. So it is inappropriate to make blanket statements

I thought the same thing, as the has density grows gradually. I can assure you that in 160feet the gas denstity and hypercapnia can quickly become an issue should you get stressed or working hard.

Gas density is not subjective.

If you could switch to helitrox for just a few seconds, you’d realize how much easier it is to breathe.

 

[beester]

I had never noticed the increased gas density issue before on deep air dives so I watched out for it on last nights dive. Still didn't notice it even though I was looking for it. St. Lawrence river, 160 feet, occasionally swimming against ~2knot current in full tech gear with 2 stages.

I think, just like almost everything else in diving, it can be an issue for some but not for others. So it is inappropriate to make blanket statements

I'm not making any blanket statements... I'm basing this on fact. There is proof that your risk level suddenly really jumps once you increase gas density above 6gr/L. (which is 40m on air)
Gas density guidelines

Does that mean that there is no personal variability in place... yes for sure there always is... we are humans. But I have enough deep experience on air and trimix to know that variables can suddenly change deep underwater, and what was maneagable just 1 minute ago is no longer maneagable the next, just with a sudden shift of workload, increase of breathing, etc.. I mean I've personally have seen this effect at only 40m while working hard... WHAM! Why take the risk when there are alternatives?

Anyway the context of this was a death at 60m, on air, single tank, no experience... and a lot of people (also I) contemplating what might have caused this, and for me together with the failed BCD the elephant in the room is deep air. Doesn't mean you can't dive deep air, doesn't mean I'm attacking your personal liberty to do what the hell you want... but I find it funny that divers doing it always come up with the same response to scientific study and deep air diving:

- I'm different (maybe better, more experienced?), it doesn't apply to me
- I've been doing it for years, it hasn't killed me so I'm right.
- My personal circumstances are such and such that trimix is not possible (gas logistics, money, training, buddies)
- JJ Cousteau (insert whatever big name old school diver from the past) did it so it can't be wrong.

I mean come on guys... just for the sake of this forum, and for new divers making up their mind on things... at least own up to what you do! I'll dive to 40m on air, and maybe even to 45m if it's just a tropical bounce dive in the red sea, yes I've done deep air dives, yes I liked being narced out of my mind at a certain stage in my diving career... yes I felt special doing those dives on air... but at least acknowledge what is being proven the last decade (PPO² limits, EAD limits, Gas density limits), instead of above excuses.

 

[dmaziuk]

Why all the hubub about gas mix? The article made it sound like a heart attack. Did I misread?

Because of the assumption that high WOB caused hypercapnia that caused loss of consciousness. It's plausible though nothing in the linked articles indicates there was over-exertion at depth or anything other than "she had a problem on descent but decided to continue".

Edit: as in, trimix would have lower WOB due to lower density of helium. Plus less chance of nitrogen narcosis, and, with hypoxic mix: less chance of oxtox.

 

[Dan]

Because of the assumption that high WOB caused hypercapnia that caused loss of consciousness. It's plausible though nothing in the linked articles indicates there was over-exertion at depth or anything other than "she had a problem on descent but decided to continue".

The BCD power inflator was found to be restricted and slow to inflate. If she had to fin & pull herself up the rope, that would increase her workload.

 

[dmaziuk]

The BCD power inflator was found to be restricted and slow to inflate. If she had to fin & pull herself up the rope, that would increase her workload.

If she were diving wet, I forget at what depth a 7 mm wetsuit wiuold lose all its buoyancy -- I think I've seen the number posted around here once or twice -- but anyway she would have been heavy on the way down. That may or may not have been "the problem" on descent that she decided to continue the dive with.

However if she was neutral at target depth, as @Ayisha said before: she'd only be venting on ascent and inflator would be irrelevant. Similarly if she were diving dry and adding air to the suit, BCD inflator should not be relevant.

 

[Dan]

If she were diving wet, I forget at what depth a 7 mm wetsuit wiuold lose all its buoyancy -- I think I've seen the number posted around here once or twice -- but anyway she would have been heavy on the way down. That may or may not have been "the problem" on descent that she decided to continue the dive with.

However if she was neutral at target depth, as @Ayisha said before: she'd only be venting on ascent and inflator would be irrelevant. Similarly if she were diving dry and adding air to the suit, BCD inflator should not be relevant.

Venting what, if there were no air in BCD at depth?

 

[TrimixToo]

I remember very clearly the sentiments many expressed when seat belts were introduced for cars, and not too far afterward when they were made mandatory for all new cars. "I am a safe driver, I don't need them," and "I'd rather be thrown clear" were common phrases when I was a small child. Today, seat and shoulder straps form a part of a restraint *system* that is itself part of a car designed to absorb energy and shield you from injury. They protect people so well that fatal accidents are a far smaller percentage of accidents, and few rational people would dream of setting out without having them fastened.

Does that mean "you're gonna die!" if you take a spin in a 1940's-era car that has no restraints at all, or one from the 60's that has only seat belts? Of course not. What it means is that if a crash happens, the combination of lack of primary and/or secondary restraints and belt pretensioners, a solid steering column, no padding anywhere except the seat, no crush zones, no door girder, and so on, dramatically increases the risk of serious injury or death.

We have learned.

We have also learned a lot about diving. We have known for a long time that narcosis happens and worsens with depth. We have long known, too, that the perception and reality of narcosis often differ markedly. We know now that high gas density increases the risk of hypercapnea, which exacerbates narcosis in addition to increasing the work of breathing. We know the density of air at 60m/200' is about 8.5 g/liter, and we know the risk curve inflects at 6g/liter.

Does that mean "you're gonna die!" at that depth on air? Again, of course not. Does it increase the odds of getting hurt or dying? Yes, also of course.

If you drive without belts fastened, you increase the risk of death, injury, and in many jurisdictions a ticket. I believe adults should be free to make the choice, personally. Likewise, I think adults should be able to make an informed choice about what gas to use at 200'/60m.

That does not mean I do not have a strong opinion about the advisability of some of these choices.

 

[Celt]

Home Office pathologist Dr Stephen Leadbeater said that a precise cause of death could not be determined from the post mortem. While not dismissing the possibility of lung injury, he suggested that it could have been either the heart attack, a cerebral gas embolism or a combination of the two.

 

[dmaziuk]

The air did not kill but I sure as hell would bet it was a trigger or very unfortunate chain reaction.

No: if the running hypothesis were correct, the trigger would be the decision to continue the dive with malfunctioning inflator, made before the WOB, the narc, the air, and so on. I.e. what John said.