deep air

[DCBC]

So it is with the deep air. The management of gas volume, narcosis, acute oxygen toxicity, ascent behavior, and the optimal operational depth of one's dive gear (all factors in planning deep dives regardless of the gases used) are challenges that cannot be met with anything approaching a definitive, this is black, this is white, answer no matter how hard one tries.

Hey Steve, I agree with what you're saying, but each of these challenges may be met with training and experience, rather than prohibition. I think that some of the training agencies have promoted a negative attitude towards deep air as an unwise option. The desire to promote other programs may overshadow the "air envelope."

As a commercial mixed-gas instructor for the past 37 years, I understand the advantages of trimix and heliox, but although trimix is a solution for a 180' dive, it's not the only solution. I believe that TDI has shown air to be a valuable option and is one of the few organizations that offers instruction in narcosis management. I applaud these efforts.

 

[dbulmer]

What is narcosis management?

 

[DCBC]

What is narcosis management?

It's largely the knowledge that narcosis will affect you, checks that the diver does to quantify the degree the diver is affected and a technique used to reduce the affects of narcosis as far as decision making is concerned. It also involves dive planning (including minimizing the need for the diver to make creative decisions) and dynamic follow-through of equipment assessment/performance and other checks. Slates are also used as reminders of procedure.

I can't attest to the lesson plan of TDI, as I'm not a TDI instructor, but these are the areas that are included in teaching Navy and Commercial divers.

 

[JeffG]

Well, if I need deco training at least I now know where not to go.

 

[DCBC]

As a side-note, PSAI does Narcosis Management programs to 240'.

 

[DCBC]

Well, if I need deco training at least I now know where not to go.

Don't worry Jeff, you need to get some experience first.... (Just kidding buddy, I just couldn't resist)

 

[Steve SDI/TDI HQ]

What is narcosis management?

Just to expand on DCBD's posting (above) management in dive planning usually refers to a process of identifying, assessing, avoiding when possible, mitigating when not, and developing a strategy to deal with precursors and outcomes associated with the risk.

Narcosis management follows a similar paradigm. Narcosis manifests itself in a way that indicates there is more at play than a direct relationship with nitrogen partial pressure, which luckily is the closest thing to a constant in the equation. Therefore, part of narcosis management consists of identifying ALL factors that contribute to "diver impairment," and understanding the likelihood of each showing up on game day; and of course how compelling the effects of each factor may be. These steps completed one can plan to avoid what can be avoided, lessen the effects of what cannot be avoided, and in the case of a deep dive where inattention or lack of situational awareness will result in a cascade of potentially threatening events, falling back on experience, training, and the arguments of one's personal comfort zone to guide the dive's planning and execution.


Hope this helps

 

[Scared Silly]

Helitrox and Trimix and all mixed gases for that matter are great tools in the toolbox and I would love to dive them every day but they are not always available nor are they necessary from both a recreational and commercial/military/scientific standpoint.

Bingo, IMHO it is all about what arrows you have in your quiver at the time. And more importantly knowing how to utilize them properly.

Folks have been mentioning the depth limits for "deep air" and the depth limit for recreational diving. Given that there is an abundance of people who lack basic math skills I'll run through the numbers - in metric cause it is easier.

Rec limit 40 meters == 5 atm == 1.05 PPO2 (rounded down to 1.0 for discussion below).

A common deep air limit 55 meters == 1.5 atm == 1.37 PPO2 (rounded up to 1.4 for discussion below).

Now where have folks seen those magic 1.0 and 1.4 numbers before???????

Hmm, being at 40 meters on air is like breathing 100% O2 on the surface. And what PPO2 do most divers use for figuring out their MOD when using Nitrox?? Why it is 1.4. There are some who use 1.2 as their working PPO2 and a PPO2 of 1.6 for deco.

 

[rjack321]

One should learn to dive deep air before learning to dive deep on trimix. As well, one should learn to climb using hemp rope before "graduating" to modern synthetics. And before getting a driver's license one should learn to drive a horse and buggy with no brakes. Zeppelins before fixed wing. Paddle a birch bark canoe before driving a ski boat.

Yes yes yes!!!!
Run marathons barefoot like God intended the Greeks to!
Hang gliders by Icarus!
Abacus before Internet!

Trimix is for soft cushy sissies who don't know how to dive like a man.

 

[DCBC]

Trimix is for soft cushy sissies who don't know how to dive like a man.

This is the same childish argument that I heard earlier. It seems that if a diver has a trimix card, he's somehow insulted at somebody else diving to 200' on air and needs to throw stones and somehow defend his choice to dive trimix. Why is that? Because he isn't competent to dive air to that depth and is insecure? I dive both and I can deal with it. Move past it.

The sissies diving trimix argument is one that I'm happy to have, but this is not a trimix thread, but a deep air one. If the discussion is on air, I fail to see how talking about another gas adds to the discussion.