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From: <kirvine@sa*.ne*>
Date: Thu, 18 Mar 1999 05:51:00 -0500
To: Kent Lind <Kent.Lind@no*.go*>
CC: cavers@cavers.com
Subject: Re: o2 for ocean deco
Again, the schedule is wrong. Kent, I have done a few of these, just a
few. Honking on oxygen while not doing the correct deeper stops is not
the answer. Abyss is giving a worthless deco here.

Kent Lind wrote:
> 
> "Lais, Bill" wrote:
> >
> > This has to be a troll, but just in case it's not:
> >
> > You're probably going to be breathing the 50/50 deeper than the O2, and
> > hence you'll consume more gas.  I think we learned about this concept in OW1
> > if I'm not mistaken.   ;-)
> 
> > Bill
> 
> Bill, what kind of deco schedules do you run that requires more
> consumption of 50/50 than O2?   Out of curiousity, I ran a sample
> profile in Abyss of a square profile 20 min. dive to 200' on 19/30 with
> 50/50 and O2 deco gases.   Using a RMV of 0.6 cf/min Abyss
> came up with deco gas usage as follows:
> 
> 50/50:   22.3 cf consumed
> O2:        22.8 cf consumed
> 
> On a typical deco curve, the shallow O2 stops are so much longer
> than the deep 50/50 stops that you end up consuming as much or
> more O2 than 50/50.  Of course, a much deeper dive profile might
> produce different results.  But for ocean diving with AL40s the
> above profile seems pretty realistic.
> 
> So, I think Ted's question about bottle choice is quite valid,
> especially given that it's much easier to fill 50/50 to higher
> pressures and O2 is a more useful gas to have in
> reserve for surface emergencies.  I happen to use two AL 40s
> for ocean deco but if I was compelled to use different
> size bottles, I'd chose the larger one for my O2.  I can jam
> 50/50 up to 3000 psi no problem.  But I'm very hard pressed
> to get more than 2000 of O2 into any bottle.
> 
> Kent Lind
> Juneau, Alaska


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