On Tuesday, October 29, 2002 7:52 AM, Michael Doelle, wrote:

>  I certainly don't know the details on the majority of these incidents.
But
> here's my guess: very few happened on a type of dive where someone decided
> to have just a quick look-see down the wall to the 200 range for about a
> minute or so.

As a person who usually has a low tolerance to narcosis and has always
required a few dives to work up to depth and reach the stage where I can
perform meaningful tasks, I have little doubt that there's a huge difference
between spending time at depth and a quick bounce dive.  Both, of course,
have the same inherent dangers in terms of pressure differences and the fact
that water is not a good breathing medium!  But the risks associated with
narcosis, (as opposed to O2 toxicity) are, to my way of thinking, increased
exponentially with time spent at depth.  Not least because of the insidious
effects of narcosis.  The fact that no discernible - or incapacitating -
effects were experienced on one dive is not sufficient to say that they
won't leap up and bang you around the back of the head on a subsequent dive.
And that, sadly, seems to be the case in many instances where supposedly
experienced divers have come to grief.

Similarly, I have little doubt that some individuals do have a very high
tolerance that almost borders on immunity.  (To relate this to
decompression, a prominent hyperbaric Doc stated just recently that some
people seem to be almost "un-bendable"!)  But they're rare people.  :-)

As Mika's already pointed out, helium - where it's readily obtainable - can,
in some parts of the world, be hideously expensive.  But cost should never
be an issue in diving.  And if something's worth exploring and diving deep
for, then, as M2 and Billy Deans wrote many years ago, "if you're not
prepared to do it right, don't do it." :-))

Despite what a hyperbaric physician stated some years ago - when nitrox was
the 'devil gas' - that, as air-breathing mammals, we were intended to
breathe only air, (he conveniently seemed to overlook the fact that we were
intended to breath it at atmospheric pressure!) air - apart from being
cheap - is not a good mix for diving.  And bounce dives ain't diving!
:-))))

Strike