I believe that trimix can be the recreationnal diving.
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Correct me if I am wrong, but I am under the impression that because helium is lighter than nitrogen, it on gasses and off gasses much faster. That property makes it desirable during long deco dives, but also makes it less "forgiving" than nitrogen. For example you may be able to spend more time on the bottom and less time at each stop, but that your ascent rate and stop times MUST be followed with more accuracy, otherwise your risk of dcs increases.
Correct me if I am wrong, but I am under the impression that because helium is lighter than nitrogen, it on gasses and off gasses much faster. That property makes it desirable during long deco dives, but also makes it less "forgiving" than nitrogen. For example you may be able to spend more time on the bottom and less time at each stop, but that your ascent rate and stop times MUST be followed with more accuracy, otherwise your risk of dcs increases.
If I had the time/money for the course and gas, I probably would use it on some of our more tricky wreck penetration dives in the 30-40m range.
These dives aren't really "recreational" dives, though.... dark, murky water and penetrating beyond the light zone..
There's also the whole question of He being less narcotic than N2, which is very attractive even on dives that do not involve deco, and He being lighter than N2, which makes it easier to breathe at depth. But as you say, the speed of off-gassing is a reason to think very carefully before considering something like this "recreational."
Maybe I should have used the phrase "no-deco." The other agencies suggest you need some experience before taking their "recreational" trimix courses. I was just wondering whether TDI had such a thing under wraps somewhere or had a strong opinion against it.
I've read alot of conflicting information on whether or not oxygen is as narcotic as nitrogen, so I am not sure you are really gaining much with helium. A diver who experiences less narc on helium may be feeling placebo. Or maybe not, I don't know, just throwing it out there...
I've read alot of conflicting information on whether or not oxygen is as narcotic as nitrogen, so I am not sure you are really gaining much with helium. A diver who experiences less narc on helium may be feeling placebo. Or maybe not, I don't know, just throwing it out there...
No helium significantly reduces narcosis regardless of your position on oxygen narcosis. My feeling is helium is expensive, and getting harder to aquire both by cost and by gas suppliers recent policies. Helium is a tool that is very useful in deeper dives and aids in certain deco schedules but to just throw some HE in a tank so you can go a little deeper for a very short time seems a waste.I've read alot of conflicting information on whether or not oxygen is as narcotic as nitrogen, so I am not sure you are really gaining much with helium. A diver who experiences less narc on helium may be feeling placebo. Or maybe not, I don't know, just throwing it out there...
I had heard helium was less narcotic, just curious about whether or not the effect is reduced, depending on how much narc comes from O2 versus N2.You do actually gain quite a lot with helium. Have a look at the results of the Meyer-Overton study, which shows a number of things... Oxygen is slightly more narcotic than Nitrogen, Carbon Dioxide is about as narcotic as Nitrous Oxide (laughing gas) and Helium is significantly less narcotic than either Nitrogen or Oxygen.