From: dave@hpdstma.ptp.hp.com (Dave Waller)
Subject: Re: Information about advanced deep diving course wanted
Organization: Hewlett Packard
Distribution: usa
Date: Wed, 2 Sep 1992 16:43:44 GMT

In article <19859@fritz.filenet.com>, scotth@felix.filenet.com (Scott Hopson) writes:
|> In article <1992Aug30.044120.21177@mdi.gwinnett.com> ddt@mdi.gwinnett.com (Dusit Tansathein) writes:
|> >Hi
|> >
|> >I plan to dive the Wilkes-Barre this year so I would like to get more
|> >information and recommendation about dive shops that offer advanced deep
|> >(mixed gas) diving course in terms of quality and pricing.  In addition,
|> >if anyone on the net has previous diving experience on this wreck, I would
|> >like to receive some suggestions about equipments, diving, etc..
|> 
|> 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.

True.

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

This is not true. The 130 foot limit has little to do with safety. Rather,
it is a result of the fact that there is too little bottom time available
at depths in excess of 130 feet while diving air with no decompression
profiles to get any meaningful work done. This is why the US Navy set 130
as their original air limit for NDL dives, and this standard was adopted
by the certifying agencies as they developed. There was an interesting
article in Rodale's _SCUBA Diving_ by Brett Gilliam, deep diver
extraordinaire, that addressed just this subject.

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

This is misleading in the extreme. There is nothing magical about the 130
foot mark that makes diving deeper than that considerably more dangerous.
If I was asked for my opinion for where the risk starts to increase
substantially for the typically equipped recreational diver, I'd place it
somewhere between 80-100 feet as that is the point at which a free ascent
in the event of a total primary air system failure becomes a questionable
proposition. However, suitable redundant breathing systems (a pony bottle
as a minimum) can extend this range to 150 feet while maintaining safety.

|> If you get BENT once you can never dive again.

This is totally, completely false. I would urge you to study this matter
more extensively before again providing advice to others about this
particular area or expertise.

|> That's
|> assuming you live the first time.

The vast majority of divers who are victims of DCS do live, and fully
recover. DCS does not have a high mortality rate.

|> Once you've been BENT your chances of 
|> getting bent again, even in shallow waters is greatly increased.

It is increased, but not greatly so. Statistics tend to suggest that there is
an increased risk, but it is far from conclusive.

|> 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.

Good advice, and applicable to ALL aspects of diving, not just deep. However,
the bulk of the information you have provided in this article is quite simply wrong.

-- 
Dave Waller
YMCA Instructor
Newsgroups: rec.scuba