Are there any entry tech courses that include Trimix?

[limeyx]

So you would advocate going from OW/AOW to mix instead of Nitrox?



Hmm ok. So lets both do a 90 minute dive to 100ft. I'll do it on EAN32, you do it on 30/30. Then we'll both ascend at 30fpm and get out of the water. Deal?

You can't do that ascent for *either* mix. No deco time would be 30 mins.

 

[limeyx]

I think this is an east coast/west coast difference in thinking. Perone if I read your previous postings right, you are in florida doing warm water/cave diving while Rainman is west cost, cold water diver so both of you are talking at a bit of cross purposes.

Ummm, not really

Hmm ok. So lets both do a 90 minute dive to 100ft. I'll do it on EAN32, you do it on 30/30. Then we'll both ascend at 30fpm and get out of the water. Deal?

Unless somehow warm water lets you ascend blowing off a huge amount of deco? (Or maybe it's the limestone in the caves?)

The profile presented was not a good choice for a comparison I think...

 

[limeyx]

Thanks for your measured reply rainman_O2,

I am a proponent of helium. Really. I have every intention of using it. However, in my experience, many of the divers I've seen recreationally, could not hold a stop without a line. Given that, I try to err on the side of caution.

The real question is though: Why is holding a stop (or not being able to) any different for Nitrox than it is for Helium? Is there really a difference?

So it's not so much about "Oh crap, Helium is too hard to dive, so let's go to 150 on 25% because it's much safer" which is ... crap (as RJack pointed out)

Also interesting to see someone not trained to dive with helium (or deco? -- not sure) propounding the pluses and minuses ....

 

[PerroneFord]

It is the opinion of my instructors, and others who I trust, that helium is less forgiving of poor ascents than air/nitrox is. Simple as that.

Probably the #1 argument here on SB is dive instruction. Yet comparitively few involved in those arguments are instructors. No, I am not yet certified to dive helium, because neither I, nor my instructors, feel it is going to be conducive to the dives I am doing, or should be doing at this time. When I have a need for regularly spending time below 100ft, I will take my helium coursework. And yes, for the record, I've done deco.

 

[KMD]

Yes, you're right. Cave divers sure do have it easy.

I don't know what I am going to do when I go up to the Great Lakes this year.

I think if you read my post carefully you will find I made no comments about which was easier. My point was that the conditions are different and thus lead to some different choices on which gasses are used.

For example, in high flow caves, why go through the work of taking a larger 70' bottle farther into the cave, when it makes more sense to bring a smaller 100% and be able to drop it off sooner.

 

[PerroneFord]

Because in talking about linear distance, sometimes getting to that 70ft bottle is VERY comforting! I've done both (though not in high flow) and there was always something VERY reassuring about getting back to that stage bottle in the Peanut Tunnel after failing to make the crossover! Believe me, when there's 1200+ feet to go between you and the exit, and you're swimming (not scootering) the closer that next bottle is, the less you sweat!

 

[wedivebc]

I certainly agree with Perrone on this point. Helium is less forgiving on missed stops quick ascents etc. A novice tech diver should be able to demonstrate mastery of controlled stopsn before injecting helium into the mix.

 

[amascuba]

I certainly agree with Perrone on this point. Helium is less forgiving on missed stops quick ascents etc. A novice tech diver should be able to demonstrate mastery of controlled stopsn before injecting helium into the mix.

While that's true, the diver shouldn't be doing any dive with mandatory decompression if the diver doesn't have proper buoyancy control in the first place.

 

[rjack321]

While that's true, the diver shouldn't be doing any dive with mandatory decompression if the diver doesn't have proper buoyancy control in the first place.

Bingo!

 

[limeyx]

I certainly agree with Perrone on this point. Helium is less forgiving on missed stops quick ascents etc. A novice tech diver should be able to demonstrate mastery of controlled stopsn before injecting helium into the mix.

I'd be interested to see any hard evidence to back up that point of view.
Or is it just "conjecture and gut feel" coupled with what instructors have told you?

Agreed on the stops, but I dont see that as any different on nitrox or 30/30 -- same thing applies (except I wouldn't be doing mandatory deco dives on 32% generally -- certainly not deeper than 100 feet)