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On Wed, 25 Jan 1995, Leslie Wilk wrote:
> I'm puzzled by your final comment. As you state, Buhlmann's tables are 
> built from the algorithm by forcing the initial descent to be instantaneous, 
> but they are USED by including the descent time in your time-at-depth. 
> From a TABLE point of view that is conservative. With respect to the
ALGORITHM, 
> if you constrain it to a fixed descent rate (say, 60 fpm), shouldn't
exceeding 
> that rate get you to depth with a lower tissue-load than the algorithm
computes, 
> thus also being conservative? 
> 
Wel, IMHO not really. It seems you are making the assumption that the 
consarvatism added to the true dive time/depth gas loading calculations 
is "fluff". What if you look at it as integral to the validity of the 
tables generated from Buhlmans formula? Remember that this was 
empirically developed. It would appear to me that the formulae accurately 
describes the gas loading/unloading mechanism. So why was instantaneous 
descent included? My guess is that first, the formulae does NOT truly 
describe the entire body with respect to loading/unloading, second, that 
if it was exactly descriptive then you would be at the "exact" edge of 
bubbling at the start of every deco stop (do we really want to be there?), 
third, the instant descent was added to create a workable table with a 
relatively low incidence of DCS. I know that ANY reduction in 
conservatism is also an increase in percentage of DCS occurance. Where 
you want to draw the line is up to you, it's your body.
I believe that  the formulae as published (including instant descent) 
works. I don't criticize this who lop of deco times, but I will snicker 
while they are in the chamber.
It all boils down to the fact that tables are educated estimates or a 
fancy crap shoot. I prefer to reduce my exposure but not to the extent 
that I won't dive.
Rambling on too much so I'm gone!
r.b.

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