From: johng@syacus.acus.oz.au (John GriffithsMel)
Subject: Re: Boyancy control with drysuits
Organization: ACUS Australian Centre for Unisys Software, Sydney
Date: Mon, 17 Aug 1992 03:14:42 GMT

Charlie_Gibbs@mindlink.bc.ca (Charlie Gibbs) writes:

>In article <1992Aug12.191716.11186@bmerh85.bnr.ca> scribler@bnr.ca
>(Dennis Richards) writes:

>>Can any of you drysuit experts explain how to handle
>>boyancy control with drysuits?

>     (I'm not an expert but I look good in a green suit. :-)

>     When ascending I try to be very alert for increasing buoyancy
>so I can react immediately by dumping air before things get away
>from me.  If I do start drifting upwards I can get a bit of time
>to hit my BC by exhaling completely (and why does my mask always
>flood when this happens? :-).

>     When I first got my suit I used it for buoyancy control almost
>to the the exclusion of my BC.  I've since changed my technique;
>when I first start down I put just enough air in my suit to take
>out the squeeze, then use my BC normally from there.  If I'm going
>deep I might put a little more air in my suit farther down, but
>that's about it.


I've been using a dry suit for about ten years and I still use it
for buoyancy control. I use an ABLJ (horse collar) so maybe thats the difference
The peole I used to dive with in the UK also all only used their suits no the
BC. I was wondering why you use your BC??. Down here I only use the dry suit 
in the winter :-)

>     Coming up I'm primarily dumping air from my BC to keep my
>buoyancy under control.  I don't usually have to worry about my
>suit until I'm up to about 30 feet.  It does take a bit of work
>to get air out of my suit sometimes (my valve is on my upper arm).
>If I have to do it I kick my feet under me to get my body upright
>and raise my left arm so that the valve is up high; this moves
>most of the air in my suit up to the valve so I can let it out.

I've a neoprene suit as well, but I don't have a valve and just dump the air
out of my left wrist, held aloft. 

The main 'problem' I've had is diving in string currents, over large ledges
where the cuurent pushes you up (away from the lobsters), so I'm always very 
conscious of any upward movement in those conditions, and ready to dump air 
as fast as possible.

>     Once I'm up to 15 or 20 feet I have to be careful, but by
>dumping air frequently I can keep things under control.  By then,
>though, both my BC and suit will be pretty much empty.  I have a
>neoprene suit; I suppose if anything it'll be a bit trickier due
>to its compression at depth (and expansion as I get shallow).


I used to have a membrane suit, and can't remember any difference but then 
its 7 years ago!
One advantage in only using the suit, is there's only one thing to adjust.
>     One more thing: Do you have enough weight?  Once you've run
>your tank down to 500 psi you're about 5 pounds lighter than when
>you started.  You should be able to comfortably stay at 10 or 15
>feet when your suit, BC, and tank are all empty (well, I might be
>a bit uncomfortable if my tank was _completely_ empty :-).

>     DISCLAIMER: I'll probably go out on Sunday, pay attention to
>what I'm doing for a change, and find out that this is all bunk
>and I really do it completely differently...

>Charlie_Gibbs@mindlink.bc.ca
>I used to be indecisive, but now I'm not so sure.

John Griffiths