From: story@sgi.com (David (Duis) Story)
Newsgroups: rec.scuba
Subject: Re: Information about advanced deep diving course wanted
Date: 2 Sep 92 23:00:03 GMT
Distribution: usa
Organization: Silicon Graphics, Inc.

In article <BtytAH.GuD@apollo.hp.com> daigle@apollo.hp.com writes:
>
>I have a question about this that has been bothering me for quite some time
>if anyone would care to comment on it.
>
>
>What I want to know is why PADI does not teach you what to do if you blow your NDL.
>What would be wrong with them teaching some light decompression diving?  

PADI and DSAT created the definition of "recreational diving" which
you see bandied about so much lately.  The definition was created
purely for the sake of defining what profiles the DSAT "Recreational"
Dive Planner could cover.  That definition is "<130fsw, repetitive,
no-decompression diving."  This definition was necessary in order to
use a shorter half-time (60 minutes vs 120 minutes) which allows
"recreational divers" a LOT more bottom time because it assumes you're
offgassing more quickly than the US Navy tables do.  This is a big
sales advantage in PADI's eyes: an exclusive table that gives more bottom time!

From the day the RDP was released, PADI, a very-much-for-profit
organization, began selling the PADI RDP tables.  All their training
materials were rewritten to stop using the US Navy tables and to use
the RDP.  Decompression was no longer discussed.  For various reasons
including the fear of liability and desire to sell RDPs, decompression
has become a taboo subject.  Since PADI currently certifies about 70%
of US dive trainees, their word sets a big trend in the market.  Add
to that their willingness to team with specific manufacturers to
promote the DSAT model into dive computers which are then promoted by
PADI, and you have a perpetual circle which leads to decompression
falling off the map.  If you don't talk about it, it isn't there.

>If I stay down too long (OK, I know, never let that happen), then I
>am SOL when it comes to knowing what the hell to do now.  Saying that
>I shouldn't have blown my NDL is simply not acceptable at that point.

To be quite fair, PADI does allow single "emergency" decompression
stops on their tables.  If you look at the special rules you'll see
rules for 8 and 15 minute stops at 10fsw, if you've overstayed by less
than 5 or greater than 5 minutes, respectively.  Of course you have to
stay out of the water for 6 and 24 hours, respectively, which can put
a crimp in your diving.

But don't use the RDP for planning decompression dives.  The RDP is
simply not set up to handle decompression diving.  

The table's limiting compartment loadings are all 93-99% of the Navy
limits, and the controlling halftime (how fast you unload) is twice as
fast as the Navy's.  That means that the RDP is LESS conservative for
almost all repetitive diving than are the US Navy tables.

The bottom line is that if you want training on decompression diving,
you won't get it from PADI.  They're just not interested -- it hasn't
been proven to them that it has sufficient return.

If you simply want more bottom time, try a dive computer and do
multi-level diving.

If you really need to do decompression diving, find another table or
use a computer (or both.)  And understand how to add safety margins,
especially for repetitive diving.

Cheers,

David Story                        NAUI AI Z9588, PADI DM 43922, EMT
story@bent.wpd.sgi.com		   Oxygen is a drug in California.