Agency choice and helium in 1st CCR class

edster

He will bend you a lot more nasty if your bouyancy goes tits up.... which it might early on.

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Joe

I suppose there is some truth to that but He, while most probably less forgiving then N2 in that instance, is not quite as unforgiving as it has been made out to be.

For it to be an issue you would have to do a Polaris Missile type ascent, in which case I'd be worring about quite a few more things than a He vs N2 bend...especially if it was after a long exposure.

nigelh

No. If you're taking a course you play by the course standards.
Give the instructor a break. If the book says air dive air.
If something did go wrong it's his neck when they ask "who is responsible?"

There is a difference with helium. Do a fast ascent and helium is not your friend. Starting out on a rebreather I was really rubbish at buoyancy. This is just the way things pan out. Some people convert faster than others.

I looked up my dumps from my MOD1. Max depth 21.6m on a seawater computer in fresh water. Even I'm not narked there. Mod 1 is not a deep water or a deco course. The skills you are learning could be done in 10m or less. Going to 20m actually made the new buoyancy stuff easier. Heck - even now holding at 3m is something I can only do if I don't think about it. If I let my brain in it all goes yo-yo on me.

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nigelh

Joe

I agree. Rules and standards should be abided by but I didn't suggest that anyone do anything contrary to course standards. I also agree there is no need to go deep. I have too much respect for anyone I take instruction from to do anything contrary to our agreed upon rules and standards. That said, if I want to dive He in training (BTW, I used air) and TDI says no and IANTD says yes I'll just go where I get what I want.

With respect to the buoyancy, my thoughts are that until you have it dialed in at 10 feet, you don't need to be at 20. Buoyancy is different and none that I know of were initially as proficient on CCR as on OC but that should be limited to being a bit higher or lower than we want to be and not trimming out as easily or as nice as we'd like. I can't imagine a diligent instructor allowing a student to do a training dive at a depth where a rapid ascent is an issue if he does not have adequate buoyancy to do the dive so (hopefully) a rapid ascent from depth isn't going to happen. That is when the potential issue of He vs N2 comes into play, in which case nitrogen isn't your friend either.

Genesis

That's fine - everyone should make their own choice. That's the point - banning something makes another's choice for them. I do it too for dives in the 80-140, but mostly due to cost.

I used to be one of those guys who thought that He was for "really deep" stuff and that I wasn't stuffed at 140 on a cut Nitrox mix. Then I filled up with 21/35 and well, I only had to do it once to understand. Then I went back with a pony full of 21/35 on some 100' dives and switched at depth (yeah, I know, don't do that when you have a significant load) and noted the immediate difference there as well.

Were there no issues with cost I'd do all my OC dives below 60' on 30/30, 21/35 or something similar. But, of course, cost on OC is an issue, even if you're filling your own tanks.
The other side of this is that you're less likely to do one since your head will be more clear.
Because there really isn't a difference in theory. How is the fact that Helium is a "faster" gas materially change anything?
A believe a greater risk is being effectively drunk when you're not totally "dialed in", having a small problem, and having it turn into a really big one because half your brain is intentionally tied behind your back.

My buoyancy sucked when I started on OC and it'll suck on CC too I'm sure. That'll pass, but until it does, why not do a bunch of 20-30' dives where you have no decompression issues to worry about at all, and your "rapid ascent" big issue is not holding your breath.

Useless MOD 1 is going to be redefined to be 10m/30', I simply think its foolhardy to limit a student's decision to use a safer gas, especially post-class.

I have no quarrel with people choosing that if they so decide. But I believe that, as with virtually all things diving, the only person qualified to make that decision is the person sucking on the hose.

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