Probably depends on the person, depth, mix and conditions.  I am far from an
expert, but I will relay a personal experience:

Some years ago when I was certainly less wise (read more stupid) and
experienced,  I used to feel relatively immune to narcosis and did an air
dive to 230' (been there and done that a few times previously), but this
time dropped down in well under 2 minutes and within 30 seconds felt like my
head was hit with a soft sledgehammer,  seeing spots and all.  Thank God the
(1) bottom was sand (2) the vis was 100+ ft (3) I had no equipment
malfunction (4) my buddies required no assitance (5) water temp a balmy 70F
(6) good ambient light and (7) no current.  If conditions 1-7 weren't as
good as they were I don't think I would be here today.  As I lay on the
bottom for a few minutes hanging by the proverbial thread and with the few
working neurons I had at my disposal, I knew I came very close to passing
out and biting the big one.

I was such a lucky SOB that I should have stayed home that day and played
the lottery because I would have won the big jackpot, instead I was a
living, breathing, prostrate and barely conscious STROKE.  While the
symptoms quickly subsided (<1 min) and I no longer felt very narced, this is
really where the insidious and even more dangerous nature of narcosis takes
over - at high EADs you are just plain stupid and relatively incapable, but
you just don't have the capacity to realize it.  Why not stack the deck in
your favor before getting in the water?  With an EAD of less than a 100'
just about any decent rate for just about anyone (unless really poor
conditions existed) would be unlikely to jeopardize the safety of the team.

Although I now believe that one's level of narcosis and the severity or
debilitating nature of its onset probably is affected by decent rates, ever
since I have adopted the philosophy to eliminate narcosis as a factor on any
dive by using only the appropriate mix to maintain a shallow EAD.  My life
and the safety of my buddies are worth the few bucks and simple hassles of
adding He to the mix.  Not to mention how much more one gets out of the
dive.

And so what if I can learn to adapt to high narcosis levels, I'm sure with
sufficient training I could probably learn how to drive a car pretty good
with a few six packs under (or over) my belt.  I wonder who would volunteer
to be my passenger during or after my training?  Discussing decent rates and
narcosis effects are sort of like asking "did you drink those six packs in
one hour or two?" as you volunteer to be my passenger.

I think with what is known today and openly communicated in tech diving
forums, high narcosis dives should really be regarded in the same light as
drug abuse.  10 years ago much less was known outside the commercial or
military communities.  The smarter ones picked up on this a least five years
ago and of course we have those that lag behind the rest of the class.  I
really don't care about the morality of this issue, it's really about what
expectations one should have of oneself and their team members.  I also
think this decision process says a lot about the maturity of a person.

My $0.02,  John


-----Original Message-----
From: Bruce R'. Miller 
To: Stephen Gillies ; techdiver@aquanaut.com

Date: Thursday, November 05, 1998 10:49 AM
Subject: RE: maximum descent rates


>> From: Stephen Gillies [mailto:max@ma*.ne*.au*]
>>  I'm looking at depths to around 50 metres for example. I've
>>  heard some divers say "we get down there asap to maximise
>>  bottom time". Is this a wise move?
>
>Some people become more narced with a fast descent.  Maybe
>it's the sudden change in pressure, or maybe the sudden change
>in ambient light.  Never happened to me.
>
>-bruce
>
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