trimix training

[DevonDiver]

I think some deep air experience really drives home the benefits of trimix. I don't think it's 'necessary', just useful (especially for those who can't believe advice unless they've seen it with their own eyes/experienced it themselves - there's a lot of people like that).

I've always toyed with the idea of either:

1) Taking a stage of TMX on a deep dive

2) Taking a stage of Air on a deep(ish) TMX dive.

Rather than doing the whole dive on deep air, just a controlled, short exposure (to either, from back-gas to stage gas) so that the impact of narcosis/gas choice can be experienced in stark contrast.

 

[Peter69_56]

Possibly it's because I am used to drinking pretty hard and used to a good buzz???? But I have never thought I felt narced at even 130ft on air. I certainly haven't felt narced on shallower dives. I have done a bounce dive down to 182 ft in COLD water and I didn't feel narced then either. I felt as if I was in total control and very aware of my gauges and what I needed to do to make sure I didn't hit the need for decompression. I'm sure everybody would agree that at 182ft I MUST have been feeling narcosis but I had no feeling of confusion and knew what I needed to do. I guess some people must experience narcosis different? I haven't had that much experience that deep so I am open to the idea that narcosis may be quite a bit more disabling at that depth had it not been a bounce dive. For those with more experience... with more time at a particular depth does it become more disabling (let's say 10 minutes at 180ft instead of just a bounce)?

And yes I just signed up for AN/DECO and hoping for trimix soon after so I have not and will not make a habit of these deep dives. Just a little experimentation to learn a little on my own.

I must admit I am the same, I feel no difference. My wife on the other hand has had N2 hits at 40+ and clearly felt them.

I know there must be an effect however I cannot feel it and can remember the dive (but I suppose how much is questionable, as I probably don't remember what I don't remember). This is down to 52 metres (172'). Much of my diving is from 35+ and I too do drink regularly although not excessively, and don't drink more than 2 drinks after diving and before the next day. Everyone is clearly effected differently. I guess I worry at what depth am I going to become sufficiently stupid to make a significant mistake due to being narc'd.

 

[Adobo]

I think some deep air experience really drives home the benefits of trimix. I don't think it's 'necessary', just useful (especially for those who can't believe advice unless they've seen it with their own eyes/experienced it themselves - there's a lot of people like that).

I've always toyed with the idea of either:

1) Taking a stage of TMX on a deep dive

2) Taking a stage of Air on a deep(ish) TMX dive.

Rather than doing the whole dive on deep air, just a controlled, short exposure (to either, from back-gas to stage gas) so that the impact of narcosis/gas choice can be experienced in stark contrast.

Great if they "experience narcosis" enough that the point sinks in.

In some cases, like a few of the replies we have on this thread, people claim that they don't feel the difference or they don't feel narc'd or whatever. They might even walk away with the impression that they are not affected to the same degree if at all as other people when deep air diving.

The thing about the exercise as you describe it, is that it does the trimix vs nitrox comparison under more or less ideal circumstances. The dive is going well, they are with an instructor and so on. But in my opinion, this is the best its on going to get. The real question is, what is the difference between trimix and nitrox when things are not ideal? When there is an issue that needs to be dealt with and conditions are demanding. When divers are now working hard and breathing hard and CO2 and gas density is also coming to play.

 

[DevonDiver]

Great if they "experience narcosis" enough that the point sinks in.

To be honest, I never really "felt" any narcosis effects up to the point I was confronted with the stark reality of partial-full amnesia. Those were dives (on air) in the 70-80m range. Even after that, I could still delude myself it was all "manageable"... I ran a complex profile, even did some penetration, and got back safely...???

The biggest reality slap came when I first used a normoxic mix on a wreck I'd dived previously hundreds of times. I could barely describe how much more I was aware of... lots of details that had previously been an haze (that I was unaware of).

I still have to balance cost versus narcosis risk (He is eeeeeeexpensive on a dive instructor salary), but the advantages are undeniable. It took me a long time, and a lot of deep dives, to accept that. The undeniable argument was the comparison in situational awareness between identical deep dives, with drastically different ENDs.

 

[nimoh]

So you're saying that if 21/35 weren't an option you'd simply refuse to dive? I'd also much prefer to have a little helium in the mix, but it's hardly impossible to manage deep air diving.

Well, technically PPO2 of Air is 1.4 ~187fsw...

Correct. I find helium to be readily available for my diving, so not an issue. Perhaps in the future as helium becomes more rare, I may begin to deep air dives, but don't see any need to start now.

Sure thing: you get separated from your team due to current and low viz on a large wreck in the 180'-240' range, have one of the various problems that can cost you a lot of gas quickly (free flow, injured hose, take your pick) and run into someone like me with double 130s of air and 50% and 80% deco mixes. Is it unlikely to happen? I hope so, for your sake. Is it a real possibility? Yes.

In your scenario, once I got the reg, wouldn't we begin our ascent? Or would you rather continue the dive?

My guess is that we would begin our ascent and be at the first deco stop around 100' in a few minutes making the narcosis minimal. This scenario hardly necessitates the need for deep air training.

 

[Mike Walsh]

If you like to find out the true benefits about trimix talk to John Chatterton. He is living in South Florida . He is the 1 to talk to & the most qualified to talk to ................. God luck ..........
scubadmike

 

[waterpirate]

You played the " hero worship " card??? I sincerely hope there is some sarcasm or humor in your statement that I missed.
Eric

Seriously, everything I learned about helium and trimix was on you tube watching the deep creek detectives.

 

[elan]

One of the reasons I did not go with TDI was that AN/DP was required prior taking trimix and my potential instructor wanted to do the DP dive on nitrox to 150 ft. I knew that was too much for me and refused to take the class.

I wonder if deep air is optional for these trimix classes. I mean, if one has already come to the conclusion that they are at their limits with nitrox at say 40m/133ft, is there any point in doing the deep air dive as part of the class? Or mandating extended range/deep air training prior to taking trimix training?

 

[rongoodman]

That ruled out a number of rebreather programs for me. There's no way I wanted to be trying to deal with learning to dive CCR while narced(it was hard enough sober). I did it with an IANTD instructor, and it was 21/35 all the way. When I did AN/DP with TDI they had started allowing some He in the mix and we did no deep air dives.

 

[Hydreliox]

I gained benefit from deep air on my ER/Trimix class. For a very similar reason to Andy, it was nice to be able to remember extra details. However, I would still choose to dive air to 55m, but I am very aware of my functional differences, and I only dive tropical waters. The other divers in my team feel comfortable with this and do the same. I would, however, be prepared to dive mix if the rest of a team refused to dive air....either way, I still want to be getting wet.

I also found it of benefit after my advanced trimix class. When you get into -100m dives it can sometimes be beneficial (depth and run time dependant) to increase the END instead of just pumping in the He. A couple of percent change in either direction with gas content may have significant detriment or benefit. It's up to you and your dive team to manage the risk.

Take it to the extreme....21O2/79He MIX - 50/50 and 100% - now, what about that O2 narcosis....?

We should each be able to learn and accept our different responses to increased gas partial pressures (irrelevant of what that gas may be). It is easy to forget that some of the 'legends' of our sport and founders of various agencies were once doing what we now consider as absurdly dangerous dives. Maybe they are, maybe they aren't.....each to their own is what I'm getting at.

As for EANx to from 0 to -30m....well, I'll let you guess where I stand on that one