Deep Air Diving - thoughts

[Air One]

Deep air diving is a part of our diving culture here in France. Many divers do it with small tanks ( 15 or even 12 l on 60 m-200 ft).
So, I did it, I was narced, feeling very well, but OMHO, unable to manage any serious problem.
So, after about 20 dives under 50 m( 150 ft) I've decided to go for a trimix course.

2 weeks ago, we went diving on a wreck in Brittany, 58 m , we were a group of 4 diving with Tx 18/35, 3 friends with rebreathers, and a group of 4 divers with air that we didn't knew.
We had double 10 l tanks of tx and 2 S80 (Nx 40 and O2), when the air divers had 1 single 15 l tank and a 6l O2 pony bottle for deco...

They were supposed to dive first, stay 12 mn on the wreck and come back.
So we jumped 10 mn after them, after 10 more mn we've seen one of them coming to us, she was panicked and apparently narced, shouting in her regulator.My buddy and me we've tryed, but without any succes to save her. We also could be dead now, I had to breath my Nx 40% on 50 m ( no more trimix).
This diver had a good experience of air deep diving, she just went too late to bed the day before. Then she lost her buddy and forgot to surface...

Avoid deep air diving.

 

[Thalassamania]

That study doesnt appear to just talk about perceived effects, it talks about objective judgement. I would be interested in reading a copy of the full paper if anyone has it, or a link to to it? ...

Gilliam, Bret. (1995). Deep Diving: An Advanced Guide to Physiology, Procedures and Systems. San Diego: Watersport Publishing.

 

[peterbj7]

2 weeks ago, we went diving on a wreck in Brittany, 58 m , we were a group of 4 diving with Tx 18/35, 3 friends with rebreathers, and a group of 4 divers with air that we didn't knew.
We had double 10 l tanks of tx and 2 S80 (Nx 40 and O2), when the air divers had 1 single 15 l tank and a 6l O2 pony bottle for deco...

They were supposed to dive first, stay 12 mn on the wreck and come back.
So we jumped 10 mn after them, after 10 more mn we've seen one of them coming to us, she was panicked and apparently narced, shouting in her regulator.My buddy and me we've tryed, but without any succes to save her. We also could be dead now, I had to breath my Nx 40% on 50 m ( no more trimix).
This diver had a good experience of air deep diving, she just went too late to bed the day before. Then she lost her buddy and forgot to surface...

Avoid deep air diving.

So are you saying a diver died? And the other three air divers were OK? What happened?

This to me is not an example of how dangerous deep air diving is, but how dangerous it is to dive deep, especially in those waters, inadequately equipped and (probably) inadequately trained. 58 mtr with a single 15 ltr and a pony is way too little gas regardless of experience level, and it sounds as if these divers weren't very experienced.

I presume you changed from your dive plan to search for or help others? Depending on the circumstances it's very risky going off your plan when you're on mix. And breathing 40% at 50 mtr? - you're very lucky not to have become a statistic yourself.

 

[Air One]

So are you saying a diver died? And the other three air divers were OK? What happened?

This to me is not an example of how dangerous deep air diving is, but how dangerous it is to dive deep, especially in those waters, inadequately equipped and (probably) inadequately trained. 58 mtr with a single 15 ltr and a pony is way too little gas regardless of experience level, and it sounds as if these divers weren't very experienced.

I presume you changed from your dive plan to search for or help others? Depending on the circumstances it's very risky going off your plan when you're on mix. And breathing 40% at 50 mtr? - you're very lucky not to have become a statistic yourself.

Yes.
The 3 other air divers were OK.

She was inadequately equiped, that's a fact.
Those divers experience is about 1000 dives each.
Of course I changed my dive plan ! And not to try to find the others.
Of course I had to breath my Nx 40 % at 50, it was nitrox or nothing.
Deep diving with air is much more dangerous because of narcosis, and narcosis can provide panic. Me and my buddy, we've talked a lot about that, about what we should have done. We have no clear answer, but we heard quite a lot of bull****.

Of course it was risky but we did not have any choice... of course we are lucky.
This is a kind of "what if" that has no good answer.

Before I was saying "I won't dive anymore under 45 with air" now I say that I even won't do it if some other diver are going on the same spot with air.

 

[peterbj7]

Diving to 58 mtr on air (properly equipped) is WAY less dangerous than breathing 40% at 50 mtr. That's a pPO2 of 2.4! And you were in what must have been a very stressful situation, in cold water. IMO you were incredibly lucky not to get an oxygen hit.

Can you say what actually happened, and how it came about that she died?

 

[Air One]

Diving to 58 mtr on air (properly equipped) is WAY less dangerous than breathing 40% at 50 mtr. That's a pPO2 of 2.4! And you were in what must have been a very stressful situation, in cold water. IMO you were incredibly lucky not to get an oxygen hit.

Can you say what actually happened, and how it came about that she died?

No, I'm not incredibly lucky, I was ascending when I finished the Tx, so only few seconds with such a Ppo2, it is acceptable for most of the people.
I can't tell this storry on internet, it's a nightmare. You just have to know that she was diving with air at 60 m, she was panicked and very probably, may I say obviously narced.
A rescue on a panicked diver is like a fight and the Tx goes quickly, when it's finish, you really have to breath something, anything...then you quicly go to 30 because you think that you're gonna have an O2 hit.

But this is not the problem, the problem is that I was in this situation because she was diving with air so she was narced and she was panicked.
We all learn to surface when we loose our buddy. She did not, she stood on the bottom and she was still on the wreck 10 mn after she lost her buddy !
This is narcosis, this is the consequence of air at 60...
I know that many people go for deep diving with air, at 60,80 or even 100 m, they say they don't feel narcosis...all right !
My feeling at 60 m with air is a very good feeling, I don't feel in danger, not at all.
But I am in danger.
So I prefer to go with trimix now, and I won't change my mind after this terrible accident.

If I talk about it, it's just because I hope that 2 or 3 people will believe me and do like me...that's all, I have no illusion.

 

[wedivebc]

We had double 10 l tanks of tx and 2 S80 (Nx 40 and O2), when the air divers had 1 single 15 l tank and a 6l O2 pony bottle for deco...

Then she lost her buddy and forgot to surface...

Avoid deep air diving.

So let me get this straight, you are doing planned deco, trimix diving and your response to a lost buddy, should have been to surface?

 

[Thalassamania]

Diving to 58 mtr on air (properly equipped) is WAY less dangerous than breathing 40% at 50 mtr. That's a pPO2 of 2.4! And you were in what must have been a very stressful situation, in cold water. IMO you were incredibly lucky not to get an oxygen hit. ...

Not really, in the bad old days when oxygen tolerance tests were still required of rebreather candidates everyone had to breathe 100% at 60 FSW to qualify. Most did fine, that's 2.8 ATA. We used to dive oxygen rebreathers at 2.0 ATA all the time. I would neither make a habit of, nor hesitate to breathe 40% at 50 MSW.

 

[sheck33]

In recreational diving people are taught to look for a min or so, then surface to re unite with your buddy. This obviously is not possible if you have a deco obligation. Of course you should not have lost your buddy in the first place.

 

[peterbj7]

Not really, in the bad old days when oxygen tolerance tests were still required of rebreather candidates everyone had to breathe 100% at 60 FSW to qualify. Most did fine, that's 2.8 ATA. We used to dive oxygen rebreathers at 2.0 ATA all the time. I would neither make a habit of, nor hesitate to breathe 40% at 50 MSW.

True, but the incidence of hits with casual divers increases rapidly once you're past pPO2 of 2.0. It's a considerable risk.

You say "most did fine". What happened to those who didn't?

When you were diving an oxygen rebreather weren't you a Navy diver, young, fit and well supported?