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> That is not what I was saying. My argument is that there is a tradeoff.
> Diving multi-gas deep mix is more complicated than diving a single back
> mix. Therefore there is some point for which the benefit of simplicity more
> than offsets the "narcosis penalty" for using a less-than-optimum mix.
> After all, unless you have some kind of automatic mixer, if the number of
> different depths exceeds the number of mixes that you carry, you are making
> a trade-off and diving a less-than-optimum mix at some of those depths.

I generally agree with George on the deep air issues; in fact I agree with
him on a hell of a lot of things. However, in this case I agree with
Richard. Multiple gas diving DOES add a cost-of-complexity, which will
balance out with some unknown value of cost-of-narcosis.  In other words,
the boundary between what depths air should be used and what depths mix
should be used is fuzzy.  Another thing that bugs the hell out of me is
this Gleason-like line-drawing thing.  What's the deal with 130 feet of
narcosis?  Just where in the hell did that figure come from?  I know that
WKPP divers use this as a maximum, and they have very good reasons for
chosing it (lots of collective experience); I know that I use it as my
limit for rebreather diving for my own reasons. But come on!  There is *so*
much variation between individual divers, and there are *so* many variables
that can affect narcosis, and there is *such* a wide scale of how much a
given level of narcosis can increase the risk under a given set of dive
conditions....that there is *NO WAY* you can draw one line at one depth
and say this will apply equally well to all divers with all levels of
experience and in all diving conditions. For the sake of Honesty at the 
cost of Modesty, I'd be willing to bet that I'm more level-headed on a 
reef breathing air at 200 feet in warm clear water than many divers would 
be at 100 feet in <10 degree C murky water deep inside a cave.  If the 
130 feet thing is intended to be a "lowest common denominator", then it's 
WAY too deep.  My first dive to 120 feet I was in major la-la land.

Aloha,
Rich

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