From: mayne@pipe.cs.fsu.edu (William Mayne)
Subject: Re: Information about advanced deep diving course wanted
Reply-To: mayne@cs.fsu.edu
Organization: Florida State University Computer Science Department
Distribution: usa
Date: Wed, 2 Sep 92 14:35:37 GMT

I don't mean to minimize the risks of deep diving or the need for training
(formal or not) and extra precautions, but I won't let some of the following
claims go by without objection.

In article <19859@fritz.filenet.com> scotth@fritz.filenet.com (Scott Hopson) writes:
>
>According to a Naui rep. which I spoke to, none of the Cert. agencies offer
>deep dive or mixed gas training. This is considered very dangerous and not
>recommended unless you go to a professional school. Some dive shops will
>offer deep dive training but they do it without the Blessing of Naui/Padi/
>YMCA or the others.

Trimix certification is available, through IAND, I believe. (I could be
wrong about the agency. I am only nitrox certified so far and I've never
done a trimix or heliox dive.) It is true that main stream agencies
devoted to recreational open water diving don't get into such technical
diving. But they aren't the whole world of scuba training and certification,
even for amateurs.

PADI's "deep diver" specialty sticks with the air-only, 130 foot, no
decompression restrictions and hence is not worthy of the name, IMO.

Some prominent and well respected deep mixed gas diving instructors I know
of are Sheck Exley, John Crea, and Tom Mount. All are cave divers but John
Crea and Tom Mount, at least, do courses for non-cave divers as well.
Billy Dean, best known for wreck diving, also does mixed gas classes.
I could also name some less well known instructors who teach trimix,
but this isn't an ad or a directory.

Sheck Exley is a school teacher, but a "professional" diver on the side
in the sense that he teaches courses for pay and is one of the most well
qualified and experienced cave divers in the world. He holds the cave
depth record, 870 feet.

In short you don't have to go to a school for professional divers, though
this is definitely advanced technical diving.  Quite a few people who make
their living at things other than diving get trained and do mixed gas diving
responsibly. They do certainly have a real commitment to diving, not just a
casual interest. Because someone isn't a professional doesn't mean that they
are qualified, even the best.

> The 130 feet limit is not an arbitrary limit created
>by these people.

It wasn't created by PADI or NAUI, but it is somewhat arbitrary.
My understanding is that it was originally the Navy standard for
ordinary operations because below 130 feet the no-decompression limit
is too short to get any useful work done. After a while it got to
be just accepted without much consideration of the reasons. There is
actually no serious problem going to 190 feet or so on air provided
you can handle moderate narcosis, have a redundant air supply, and are
prepared for decompression. I wouldn't just go to 190 without working
up, or rather down, to that depth, as well as taking extra precautions.
But you don't have to be Superman or even a super diver to do it with
experience and preparation. It shouldn't be taken lightly. Neither
should it have a macho or dare devil mystique which I fear exaggerated,
alarmist descriptions of the supposed dangers by people who haven't
done it may suggest.

> Most people are not aware of the potential dangers that
>exist below 130 feet.

Including many preach the 130 foot limit, I dare say.

> If you get BENT once you can never dive again. That's
>assuming you live the first time. Once you've been BENT your chances of 
>getting bent again, even in shallow waters is greatly increased.

Decompression sickness is seldom fatal, though it can be. One DCS hit
does not mean that you can never dive again. It is not clearly established
that getting bent once greatly increases your risk on future dives. It
may increase your risk. It may just indicate that you are unusually
susceptible. A minor hit may not have any long term consequences at all.
This is not as clear cut as you make it out to be.

> One deep
>dive is not worth your life. When doing deep and extended diving you need
>to seek professional training and be very aware of the dangers involved.

This is the only thing in this post which I agree with, depending upon
your interpretation of "professional training". If you mean training in
a school for commercial divers no. If you just mean well qualified
instructors for technical diving, yes.

>Scott Hopson   (scotth@filenet.com)

Bill Mayne