Newsgroups: rec.scuba
Date: Mon, 17 Aug 1992 21:28:29 -0400 
From: "Peter A. Simon" <ps3p+@andrew.cmu.edu>
Subject: Re: Boyancy control with drysuits
	<1992Aug17.184531.15256@mksol.dseg.ti.com>

>I've always wondered if it would be feasible to place some sort of emergency
>release near one ankle, with a pull going back to the waist or chest.  Maybe
>even build in a pressure relief valve?  I know I'm not the first to think of
>this, so would one of the ice cube divers enlighten me?

While undergoing commercial diver training we were told horror stories
about "blow ups," i.e., uncontrolled ascents when wearing "heavy gear." 
If coming up at terminal velocity  head first we could dump air through
our helmet valve and get our ascent under control.  However, coming up
feet first we had the real problem that when upside down the exhaust
valve allowed the helmet to flood and the cuffs alone couldn't dump as
fast as necessary (assuming that we weren't in a Michelin Man
configuration anyway).

So, we were told, NEVER let your feet get above your head.  The U.S.
Navy mandated wearing heavy, lead shoes.  We chose to adopt four to six
pound weights on our ankles (taped on in such a way that they'd NEVER
come off).  I always wondered what the big deal was because I saw no
reason why one could not or should not incorporate some sort of dump or
over pressure valve in the ankles (20 years ago, Dillon).  I asked
various people (with years more experience than I had) at various times
why this wasn't done and never got a satisfactory answer.  Now *I* have
years of experience and if anyone were to ask me that question I
wouldn't have a satisfactory answer.  

Now, to dry suits.  Two years ago I dove four hours a day, six days a
week for six weeks.  I was frequently in a position where my ankles were
above my head.  Since I was finning (vs. walking on the bottom) I was
using only two pound weights on my ankles (held on by non-quick release
straps).  I was also using only my dry suit for buoyancy.  I had no
problems other than that my feet would feel uncomfortably light at
times, and that I'd have to do a tuck to get in a position to dump the
air in my feet.

Why did I not use my BC for buoyancy control, since it would have
eliminated both the light feet and dumping problems?  Simple:  I'm a
reactionary, old fart and I resent being told I have to wear "new
fangled shit" when I reckon old fangled shit will do just as well. 
"Being told to wear" does not necessarily translate into "having to use"
and I didn't.

Maybe using the BC for buoyancy would have worked just as well, maybe
not.  Maybe next time I'm in that situation I'll try it, just to see
what it's like, maybe not.  What I get a kick out of are the people who
post dogmatic statements like, "the dry suit must have just enough air
in it to prevent squeeze, while buoyancy is the exclusive provenance of
the BC."  Come on, guys, get a grip!  Who sez?  If *you* say give a
reason--a compelling one, not a "'cause I think it's reasonable" one. 
We all know that opinions are like ass...  Never mind.  

By the way, does anybody know (preferably by having measured it
themselves) the terminal rate of ascent of a diver wearing a wet or dry
suit?  I've come up at full tilt in a wet suit, no weight belt, full BC,
kicking for all I was worth (we're talking panic here, I won't hide it)
and I don't think I exceeded 100'/minute.

Peter Simon
NAUI Inst. #1434

-peter

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