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On Wed, 25 Jan 1995, Frank Deutschmann wrote:

> Ronnie Bell sez:
> > 
> > You are quite wrong if I may say so. When carefully reading THE BOOK I 
> > realized that I did not need to code for the descent (in my table 
> > generating program). Buhlmans model and all TABLES generated from 
> > a true implementation thereof implicity ongas "as if" you had made a 
> > instant drop to the bottom. Buhlmans model assumes a 60 fpm descent rate, 
> > and any descent faster that that reduces ANY conservatism that instant 
> > descent may have provided.  
> 
> I think you need to read "THE BOOK" again, if I may say so.
> 
> The MODEL makes no assumptions about descent rate; it simply describes
> the theoretical change in gas loading given a delta depth and a time
> period over which the delta took place.
> 
> The TABLES were generated with an instantaneous decent.
> 
> Oh, and by the way, can you PROVE (and by prove I mean proof by methods
> other than vigorous assertation) that descending faster than the descent
> rate built into a table decreases conservatism?  Of course, we all seem
> to assume this is so, but can you actually prove it?  Keep in mind that
> if you simply show an increased theoretical gas loadinggiven by the model
> that does not PROVE anything, other that ACCORDING TO THE MODEL conservatism
> is lessened.
> 
If you look at the incidences of DCS and the "bare" model you'll see whay 
it was added. I know that many divers feel DCIEM tables are too 
conservative, but if you review the process through which they were 
developed I think you'll see why the instant descent was incorporated 
into the model. Also, tink about this, now matter what the bottom time 
(well be reasonable) the added fluff will be there. Adjusting the A&B 
values will not give you that same fluff irrespective of bottom time and 
as a matter of fact seem to asymtopic at some point.
Other pertinent stuff in my other post to the list.
r.b.

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