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> Ok, if I can paraphrase - The deeper one is the more nitrogen is being 
> absorbed because of the higher PP. What you (Buehlmann?) seem to be 
> saying is that the intention of the faster ascent rate from depth is to 
> get the diver into a shallower depth, where the PP of nitrogen is less, 
> in the quickest but safest time then slow the ascent to allow 
> off-gassing to take place. That's probably a bit simplistic but in broad 
> terms is that correct?

Yes, that's what the compartment-based models sa - get the hell out of
deep water quicklyy.  George is right that Eric can explain the bubble 
physics better, but here's my visialization of it: 

The slow initial ascent is to keep the bubbles (which exist already 
anyway for a variety of reasons) relatively small.  A fast ascent in deep 
water will allow the bubbles to get larger, and large bubbles take longer 
to "offgas" into the surrounding blood/tissues because the pressure 
inside the bubble isproportionally less.  It's much more complicated than 
this, but you can think of compartmentt-based models (like Buhlmann) as 
managing dissolved gas molecules, and bubble-based models as managing 
dissolved gas molecules in additio to gas-phase molecules (bubbles).  The 
upshot when you work out the math is that the bubble models suggest a 
need for much deeper initial decompression stops (= slower deep ascents).

But again, this is all theory - as Robb put it, our lab-coat 
rationalization of how it works.  All I know for sure is that I feel much 
better after long deep decompression dives if I interject additional deep 
stops.

As for computers - I just spent more money getting two EDGE computers 
overhauled than it would have cost me to get any one of the fancy new 
computers.  Why?  Two reasons.  One, the EDGE is the only computer that 
displays whiat I consider to be the only useful information - the tissue 
graph.  And two, after thousands of dives I have come to learn how to 
modify my decompression profile based on what the EDGE tells me - I'm not 
sure if my modification algorithm will work on a different computer.  
Tables are swell for certain dives, but they are useless to fish-nerds 
(like myself) diving all over the place on vertical reef walls.

Aloha,
Rich

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