Reconsidering Deep Air?

[scubadada]

What measures would that be?

Besides limiting depth and using helium, many things are often mentioned:

Limit CO2 accumulation by maintaining a normal breathing pattern with full exhalation, avoiding strenuous exertion
Stay warm, dive rested and sober
Avoid excessive task loading, dive your plan
Be competent and experienced in your skills
Watch yourself, consider slate reminders, gauge checks, trust your instruments,
Watch your buddy
If in doubt, ascend

Suggestions apply to suspected narcosis within rec limits as well as deeper. I don't disagree that one must be very careful with diving air or lean nitrox below rec limits, or within rec limits, if you are susceptible to significant nitrogen narcosis

 

[grf88]

Besides limiting depth and using helium, many things are often mentioned:

Limit CO2 accumulation by maintaining a normal breathing pattern with full exhalation, avoiding strenuous exertion
Stay warm, dive rested and sober
Avoid excessive task loading, dive your plan
Be competent and experienced in your skills
Watch yourself, consider slate reminders, gauge checks, trust your instruments,
Watch your buddy
If in doubt, ascend

Suggestions apply to suspected narcosis within rec limits as well as deeper. I don't disagree that one must be very careful with diving air or lean nitrox below rec limits, or within rec limits, if you are susceptible to significant nitrogen narcosis

Another thing I discovered is to avoid rapid descents.

 

[Celt]

What I’ve noticed in this tread is how quick people are to condemn someone making relatively deep air dives but not a word of criticism for the 800 feet dive described in the video where even trying to swim could kill you.

 

[PfcAJ]

What I’ve noticed in this tread is how quick people are to condemn someone making relatively deep air dives but not a word of criticism for the 800 feet dive described in the video where even trying to swim could kill you.

If you want to go to 800ft (oof), there's really no other way to do it. Gas density is just a thing at those depths.

If you want to dive to "deep air" depths, you could do it on trimix and reduce that risk.

 

[helodriver87]

The difference is risk mitigation. An 800ft dive is a massive undertaking and if someone's going to do that, they're going to plan it meticulously with precise gas mixtures, safety divers, etc... There will still be a lot of residual risk remaining, but that's the nature of the beast. Doing a 180-190ft dive on air is accepting additional risks that can be mitigated, but the diver chooses not to. So while the 800ft dive may be far riskier, it's riskier because of a level of inherent risk that can't be eliminated. The same is not true of choosing not to dive a better mix.

 

[Akimbo]

It is always reasonable to ask why you want to go deep on any gas. The answer to risk avoidance is stay shallow rather than use Helium. As most of you know, Helium will help reduce risk but is a long way from eliminating it. (Not everyone reading this thread is a trained technical diver)

There is a long history of working dives on air far deeper than modern training agencies like to admit. However most were accomplished using surface supplied systems and divers with literally months (8 hours/day and 5 days/week) of training and many years of experience. Surface supplied doesn't change the physics or physiology but dramatically changes the risk profile.

For perspective, all US Navy First Class Divers made dry and wet chamber runs to 285'/87M when the PPO2 limit was 2.0 instead of 1.4/1.6.

We were taught techniques to manage CO2, in the body and the gear, which produced nearly immediate results. Narcosis symptoms didn't disappear, but improved quite noticeably by the diver and topside support crews.

The US submarine F-4 sank off Pearl Harbor Hawaii with all hands in 1915. She was in 306'/93M of water. All divers survived though efficiency was severely reduced by Nitrogen Narcosis. The F-4 salvage was the leading motivator to develop HeO2 diving in the 1920 and 30s at the US Navy Experimental Diving Unit.

Obviously, deep air risks can be managed but it comes back to the original question, why are you making the dives? Exploring wrecks in remote locations with minimal facilities might be one reason for deep air. The cost and availability of gas might be another.

In my experience, slowly working deeper in order to learn to manage symptoms is a critical component. There is considerable debate regarding short term diver acclimatization to Narcosis. It may not be measurable by conventional cognitive tests, but higher work efficiency was consistently reflected in diver's performance on all the commercial deep air jobs I have been on.

 

[Celt]

Wow what a double standard, it’s justifiable to push the limits of helium but not air.

 

[jadairiii]

.....Surface supplied doesn't change the physics of physiology but dramatically changes the risk profile...... commercial deep air jobs....

25 year old commercial/navy diver, physically fit, with surface support and on an umbilical, vs 50 year old recreational diver, 30 lbs over weight on open circuit/RB. Not even a discussion.

 

[Celt]

If you want to go to 800ft (oof), there's really no other way to do it. Gas density is just a thing at those depths.

If you want to dive to "deep air" depths, you could do it on trimix and reduce that risk.

That’s just it, you don’t have to. It’s a personal choice.

 

[helodriver87]

You can use the same techniques to minimize narcosis when using trimix. You can also adjust the mix to further reduce risk. You can't do that with air. It's not a double standard when one choice can be made measurably less risky.