NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/rec/scuba/6189

Text File | 1992-11-23 | 6.3 KB | 133 lines

Organization: Carnegie Mellon, Pittsburgh, PA
Path: sparky!uunet!cis.ohio-state.edu!news.sei.cmu.edu!fs7.ece.cmu.edu!crabapple.srv.cs.cmu.edu!andrew.cmu.edu!ps3p+
Newsgroups: rec.scuba
Message-ID: <[e-mail]>
Date: Mon, 23 Nov 1992 16:20:44 -0500
From: "Peter A. Simon" <[e-mail]>
Subject: Re: Free ascent
In-Reply-To: <[e-mail]>
Lines: 122

Excerpts from netnews.rec.scuba: 22-Nov-92 Re: Free ascent by William
[e-mail]
> In article <0f40=[e-mail]> [e-mail]
(Peter  > Simon) writes:
> >
> >I did my first emergency free ascent from 80' with no problem because
> >every time I ascended from the wreck we were diving on (three times a
> >day for 4 weeks before the incident) I did a free ascent "just for
> >practice."  I was damn glad I did when my reg finally self-destructed.
> >I remembered the only thing I had to and that was to EXHALE.  Luckily, I
> >didn't miss any decompression stops.
> >
> >The second time was from 200' where I had run out of air and believe me,
> >it was scary.  Again, though, successful, because I had continued my
> >practice to come up without the regulator in my mouth "just for
> >practice" from depths as deep as 150' to my first stop.
> >
> >I would be interested in reading comments (not flames) pro and con on
> >recreational divers practicing "just in case."
> >
> >Peter
> >NAUI Inst. #1434
>
> There may be a fine line between a comment and a flame here.
>
> I wouldn't think that practicing free ascents from deeper
> than some not very deep limit would be risky because you
> would either be ascending too fast for practice or practicing
> too slowly for a real emergency. Ascending from 150 feet to,
> say, a 30 foot stop should take at least 2 minutes. That is
> assuming an ascent rate of 60 feet per minute. Even slower
> rates are now advised for safety. (Yes, I know faster rates
> aren't so bad at greater depths.)
>
> But I expect that if I was really out of air slowing my ascent
> rate would be the last thing on my mind. It is more important to
> reach the surface, and I wouldn't take chances estimating how
> slowly I could go and still make it on the air in my lungs.
>

I should have made it clear that when I practice a free ascent I am
always following a downline up (although not pulling myself up by it)
and I have the regulator in my hand ready to use (it's not in my mouth
because it's too damn tempting to use!)

So, having the regulator and a downline at hand I am mentally easy about
coming up somewhat leisurely.  The two minutes sound scarier than they
are which is why I thought to do this to begin with--to find out how bad
it really was.  In fact, to find out if it was even possible.  Knowing
that it is increases my confidence hence the liklihood of panicking is
lessened.

You are absolutely correct about rate of ascent not being on the top of
your priority list when you run out of air. It sure wasn't on mine.  But
it had better be somewhere in the back of your mind!  You have to
remember that you don't want to drop your weight belt or there's a real
liklihood of being totally out of control, the same with remembering to
keep your hand on the dump valve of your BC.  That's one of the reasons
I practice.  I remember clearly a lecture by Glen Egstrom where he told
us that the leading cause of death of scuba divers was panic.

> For deep diving it is more appropriate to practice prevention
> than to practice free ascents. By prevention I mean things like
> good air (or gas) management, redundant breathing apparatus, buddy
> contact, and maintaining equipment to minimize the risk of
> equipment failures. (I add "if appropriate" to buddy contact since
> I don't want to appear to encourage reliance on buddies in extreme
> situations.)
>

You are absolutely correct that it is appropriate to practice
prevention, and to use gear and techniques that increase the liklihood
of survival.  But it is also appropriate to realise that it just may
happen that everything is going to turn to s*** all at once and you'd
better have a plan...

> At the risk of crossing over into flames, I'd like to ask: What
> kind of diving are you doing to have had to do not one but (at
> least) two free ascents from significant depth? How did you
> manage to run out of air at 200 feet? Think of this as accident
> analysis in the interest of knowing what to look out for rather
> than questioning your practices.
>

In the first case the second stage of my regulator, which was two months
old and had been well rinsed after every dive, began freeflowing.  It
was towards the end of the dive so I didn't have all that much air and
to make it worse I was in the hold of a ship and had to swim
horizontally to get to the hatch.  Although buddy diving, we were
working and tended to go our seperate ways once at the job site.
Visibility in the hold itself was zero.  By the time I got to the down
line I had no air. Since I had practiced the ascent I didn't bother to
see if I could get air from the reg without also getting a lungful of
water as I ascended.  We always had tanks suspended at our stops and I
was able to make it to ten feet and do my decompression.

The lessons here may seem obvious, and most divers would never have
gotten out of sight of their buddy.  However, in my line of work, while
one may always have a choice of diving safely or not diving at all, we
wouldn't be doing what we do if we didn't sometimes opt for the third
alternative of diving anyway.

The problem with the regulator was caused by electrolytic action between
two dissimilar metals creating corrosion by-products which jammed the
valve.  US Divers was reluctant to fix it under warranty even though the
dive shop said that they had seen this problem with this regulator
several times before.  Although this was many years ago and that
particular regulator is no longer sold, I have not owned a US Divers
regulator since (I'll forgive people their mistakes but not for not
admitting them).

I'll spare you the details of the 200' free ascent but the lessons there
are: NEVER dive without a buddy who's reaction to narcosis you know and
DON'T count on your ability interpret the dials of your watch and your
tank gauge, or even know the difference between them at deep depths.

But I'll repeat, given that I made the mistakes, my practicing free
ascents again may have saved my life.

Peter
NAUI Inst. #1434