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On Thu, 25 Jun 1998 Adriaan_Haine@ce*.be* wrote:
> Dear all,
> Having some idle time I decided to compare some decompression
> planners, on a theoretical dive to 30 msw for a duration of 60
> minutes. To keep things simple I chose air as my travel, bottom
> and deco gas. I compared the Buhlmann tables to the following
> programs: Proplanner, Abyss, Tausim and DECOMP.
> All programs are (more or less) Buhlmann based.
> The results were rather surprising (to say the least)
> 1.Using Proplanner :
> DECO:  4 mins at 9 msw
>       16 mins at 6 msw
>       33 mins at 3 msw
> total DECO: 53 minutes
> 2.Using Abyss : (abyss 100 algorithm)
> DECO:  2 mins at 9 msw
>       15 mins at 6 msw
>       39 mins at 3 msw
> total DECO: 56 minutes
> 
> 3. Using the IANTD tables (Buhlmann) :
> DECO:  7 mins at 9 msw
>        6 mins at 6 msw
>       46 mins at 3 msw
> total DECO: 59 minutes
> 4. Using Tausim : (freeware available on the INTERNET)
> DECO:  2 mins at 9 msw
>       24 mins at 6 msw
>       47 mins at 3 msw
> total DECO: 73 minutes
> 5. Using DECOMP : (freeware available on the INTERNET)
> DECO:  1 mins at 9 msw
>       12 mins at 6 msw
>       28 mins at 3 msw
> total DECO: 41 minutes
>

This doesn't surprise me at all, and I'm willing to bet
than any of them would get you out of the water safely.
The primary difference you see is that some of these
programs have default or "built-in-minimum" conservatism,
and some (like DECOMP) have absolutely none.  If I set
ZPlan with zero conservatism, I get 1,13,29 for a total
of 43 minutes.  Believe it or not, that is within a minute or two of
the value that Buhlmann intended you to get, which, you
will notice, is closest to DECOMP, the most un-padded
of the ones you list (variations of a few minutes are OK for
a dive like this, due to minor implementation differences).

BUT, if I stick in 15% conservatism, look what happens:
3, 17, 37, for at total of 57 mins.  Look familiar?
If you were getting money for your deco software, would
you add in 15% conservatism to cover your butt in
a litigous society?  90% do, and I can't blame them.

So what you should do is, instead of assuming all the
others are correct, and DECOMP will get you bent, is
realize that DECOMP is the only true one in the bunch,
and the others are overarchingly conservative to varying
degrees.

> 
> Ps: Will, I would have loved to see what Zplan 1.03 makes of this, but am
> unable to run it on my OS2/Windows 3.1
> based notebook.
>

s'OK, I did it for you. ;)

Regards,

-Will



 
> 
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