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Date: Wed, 07 Jun 2000 08:30:22 -0700
From: David Chamberlin <dwc@na*.co*>
To: Paul Braunbehrens <Bakalite@ba*.co*>
CC: techdiver@aquanaut.com
Subject: Re: Oxygen Toxicity - using 100% in open water
Paul Braunbehrens wrote:
> 
> Dave, thanks for the reply!  At what point do you worry that O2 is
> going to kill you?  How closely do you monitor your depth?

Well, since you're asking me, I'll tell you what I do and think - but
compared to the vast majority on this list I'm a newbie at this, so
don't take what I say as gospel.  Wait for the "big guns" to weigh in on
it.

I actually try not to monitor *too* closely.  It makes the hangs seem to
take even longer (that whole watched pot never boils thing).  I
generally make sure I keep it between 22FSW and 18FSW, which I find is
pretty easy even if I'm not monitoring that closely.  However, one time,
I'm ashamed to say, I kind of fell asleep on my stop (never listen to
that guy with the pointy horns and tail sitting on your shoulder when he
says it's OK to "rest your eyes" for a few seconds) and awoke to find
myself at 25 FSW.  I was concerned, but not enough to spit out the reg
or even to hurry back to 20FSW.  In fact, I think the latter is
definitely the wrong thing to do.  Exertion is a contributing factor to
CNS tox.  So I just adjusted my bouyancy and worked my way back to 20FSW
as quickly as I could without exerting myself.  

Considering the dives I expect you to do, and for that matter most any
open water dive in the conditions we have, the decos aren't going to be
too severe, which means as long as you don't push your PO2's for your
bottom gas, then your body hasn't been too "beaten up" by O2 by the time
you get to your 20FSW stop.  Given that, I think *short* periods of high
PO2s shouldn't be that much of a concern.  If while trying to maintain a
20FSW stop on O2, you find yourself down at 25FSW, I wouldn't find that
cause for alarm (except as an indication of bouyancy control...), I
would just make sure I got myself back to 20FSW as quickly as possible
in a relaxed fashion.  Now if I were to find myself at 30FSW, then I'd
be a little more concerned (for multiple reasons) and would probably
switch to backgas while I got myself back up to 20FSW.  

>  I'm thinking about a reel as well,
> but I'm not sure which one to get.

I wouldn't be too concerned about a reel yet, especially with the type
of diving we do.  The spools should be just fine (though I'd get two if
I were you - one that you can dedicate to your sausage as a deco line
and one for everything else).  If you do want/need a reel, the EE reel
is a fine reel (of course).

> BTW, when you do a hang from your float, do you have a weight
> attached to the float?

Technically yes.  One of Phil's friends came up with a pretty cool
little contraption for the spool attached to the lift bag (or safety
sausage).  Go down to REI and get a one pound exercise weight.  Take the
line off your spool (or just save yourself some money and buy raw caving
line instead of buying the line on a spool) and wrap it around the
exercise weight (make sure you attach the line to the weight!).  Attach
the line to the bag/sausage and wrap the bag/sausage around the weight. 
Now when it's time to deploy, you grab the bag, let it unroll and let
the weight and line fall out.  Add air to the bag/sausage (don't hang on
to it as it ascends! :-).  When it hits the surface, start your ascent.

-Dave
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