Helium prices ...

[rjack321]

I think there is no scientific data to support this, but my gut feeling is that, over time, you don't develop a "resistance" to narcosis, but you can get better at functioning at a near-normal level, as you get more experienced with narcosis.

In other words, whatever signs or symptoms you have noticed in yourself that caused you to conclude you were "pretty narced" at 42m are things that, if you keep diving at or near that depth range, with no helium, over time you might eventually notice that those same signs or symptoms are consistently lessened.

But, that is just an unsupported-by-any-science-that-I-know-of feeling that I have.

This was actually investigated with multiple divers and multiple metrics of narcosis over a decade ago and there's zero evidence to support your feelings. In fact, there is good evidence that lots of experienced divers feel that they are improved/adapted when they actually aren't. So you are in good company.
Dissociation of the behavioral and subjective components of nitrogen narcosis and diver adaptation. - PubMed - NCBI

 

[stuartv]

This was actually investigated with multiple divers and multiple metrics of narcosis over a decade ago and there's zero evidence to support your feelings. In fact, there is good evidence that lots of experienced divers feel that they are improved/adapted when they actually aren't. So you are in good company.
Dissociation of the behavioral and subjective components of nitrogen narcosis and diver adaptation. - PubMed - NCBI

If the Abstract is accurate and reflective of the whole study, I'd say it does not refute what I said whatsoever.

The study was performed over 5 days, using 11 "experienced divers", compressing them once a day.

The study does not offer any scientific support whatsoever for whether a "new" diver might achieve some behavioral adaptation over a period of, say, 100 dives, as they go from "new" towards "experienced".

The 11 experienced divers in that study might have already all achieved their maximum amount of behavioral adaptation before the study started.

It might take more than 5 dives to achieve quantifiable behavioral adaptation.

Show me a study that starts with new(-ish) divers and covers 100 dives.

 

[Kyle0692]

Narcosis is so variable, at least for me, that I don’t really think I would ever be able to confidently say for any given dive that I would be able to function just fine and have no uh-oh’s while being impaired.

This thread definitely has me interested as I am a new technical diver with only a handful of dives so far at the AN/DP level (deepest 155’). I was narced pretty severely on the 155’ dive and also have been to 130’ and not really felt anything with warm water, little current, and good viz. My instructor is proposing I take Extended Range with him in the future when I am comfortable, but I’m leaning against it due to the high variability of experiences I have personally with narcosis. I am leaning towards going to Trimix in the future and skipping Extended Range as I see it has more utility, however, helium prices are pretty rough too lol. I do typically 100+ rec dives a year in South Florida so if I did 15-25 tech dives a year I think I would be doing pretty good. I could handle the helium bills for those dives. Safety first!

 

[Jared0425]

Pure grade Helium in the Detroit area is now $3.00 per foot. Deliveries are sporadic and deliveries to non essential businesses are on hold. Welders grade is also hard to come by. A friend bought a K-bottle of welding gas for $470.

 

[abnfrog]

the only difference is the cyl is cleaner in 100 %

 

[Valyngar]

Narcosis is so variable, at least for me, that I don’t really think I would ever be able to confidently say for any given dive that I would be able to function just fine and have no uh-oh’s while being impaired.

This thread definitely has me interested as I am a new technical diver with only a handful of dives so far at the AN/DP level (deepest 155’). I was narced pretty severely on the 155’ dive and also have been to 130’ and not really felt anything with warm water, little current, and good viz. My instructor is proposing I take Extended Range with him in the future when I am comfortable, but I’m leaning against it due to the high variability of experiences I have personally with narcosis. I am leaning towards going to Trimix in the future and skipping Extended Range as I see it has more utility, however, helium prices are pretty rough too lol. I do typically 100+ rec dives a year in South Florida so if I did 15-25 tech dives a year I think I would be doing pretty good. I could handle the helium bills for those dives. Safety first!

Or you don't go to Trimix class and switch to ccr now and save money on long run. Check out TDI helitrox course for ccr, gives you helium at start.

 

[abnfrog]

+1 for the ccr way

 

[Dominik_E]

Personal opinion (not a CCR diver): sustainable use of helium means CCR. Not advocating OC trimix for ever shallower depths.

 

[Jared0425]

Bring down the price of a CCR and improve their safety features and maybe they'll catch on.

 

[helodriver87]

I've got a couple thoughts on this. I did the GUE thing (T1 to CCR1). So I did a decent chunk OC mix dives in the normoxic range. Still do occasionally. There's value in seeing gas consumption at depth on OC and getting a feel for it. There's value in doing gas switches during a multi stop ascent. Because these are all things you'll have to do in a real bailout situation. That said, CCR2 was introduced in place of T2 in part because people were doing big CCR dives that, while they were technically certified for (via T2), they weren't ready for on a CCR, but also because helium is crazy expensive many places and the cost of doing 25 proper T2 dives was nuts.

For me personally, going straight to CCR without any real technical training beyond an AN/DP ticket still seems irresponsible. But I do think it's getting harder to justify extensive hypoxic OC trimix experience as helium goes up and units get more reliable.

I'm still undecided on T2. I know there's still value in it, but with how CCR2 is structured, it almost seems redundant. And for the cost, it's tough to justify.