Mailing List Archive

Mailing List: techdiver

Message Display

> >>
> >>Is that conclusion based on just theory, or do you have something more 
> >>substantial to go on?  If the latter, I'd like to hear about it. Or, do 
> >>you just mean it's better because you can start the O2 deeper?
> >>
> >>Rich
> >>

> We could add that by staying deeper, it is easier to prevent bubble
> formation (you know, the reason for deep stops?;).  Off gasing efficiency is
> constant regardless of the depth while breathing O2.  So the deeper you can
> stay (limited by O2 toxicity), the better it is.  

That's what sentence number two of my post was referring to.  I was asking
George about advantages over and above that.  He told me some bovine
excriment about uniform pressure over the body, and some other more useful
stuff. The problem with the "theoretical" advantages is that you can argue
it "theoretically" either way.  I could say that very high PO2s leads to
vasoconstriction and thus reduced perfusion (and reduced offgassing), but
being immersed does the same thing.  Which is the over-riding factor?  I
dunno....and I actually don't care.  What I'm interested in are the
anecdotal and insightful experiences that people like George can offer
after trying this sort of thing.  Lately I'm becoming a bigger believer in
looking at what really works, rather than trying to predict what works
based on our meager understanding of all the factors involved. 

> The DCIEM recommend only their SurD O2 (table 3) table for extreme exposure
> dives.  This involves decompression at a constant depth of 40 feet in a
> chamber, once a 30 feet stop is completed in-water.  Their in-water O2
> decompression table (table 2) involves decompression at a constant depth of
> 30 feet (with helmet).  For most of us, they adapted table 2 so it involves
> O2 decompression at a depth of 20 feet (table 2m).
> 
> I talked about that with Ron Nishi (DCIEM) a few years ago.  He explained me
> that bubbles have less chances to form as you stay deeper.  For myself, I
> always pull my 10 feet stop to 15-20 feet.

I always "clear" my deco time at 20 feet or deeper, and this seems to be 
an important factor in my experience.  I have a lot of respect for Ron, 
but I'm less and less enthusiastic about speklatin' what the underlying 
mechanisms are anymore - we just don't know enough yet.

Aloha,
Rich

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]