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I posted the following in rec.scuba, in response to a posting made by
Mr. Mike Cochran about the new NEMESIS II lines of computers. I am
re-posting it here because (a) my questions were confined to the STANDARD
NEMESIS II. Techdiver readers may have similar questions about the
NEMESIS II Nitrox relative to the previous-generation (last year) NEMESIS
Nitrox. (b) Michael Heltemes who introduced himself as "New Kid on the
Block" (from my memory) on techdiver recently without identifying himself
as affiliated with any of the Cochran companies, may have some light to
shed on the subject.
-------------------- rec.scuba posting text below -----------------------
In article <3gjp32$sln@ix*.ix*.ne*.co*> in response to Thom,
MCOCHRAN@ix*.ne*.co* (mike cochran), aka
Mike Cochran (Cochran Undersea Tech.), says on 30 Jan 1995 22:26:42 GMT
> To be fair, you should be aware that our NEMESIS II Nitrox and standard
> NEMESIS II also figures temperature, breathing rate, ascent rate, and
> reverse profiles into the decompression calculations.
: ... advertisement-sounding material elided ... :
and concluded the post offering,
> Want more info, just ask.
To be fair to Mr. Cochran, I'll point out to readers that I had made one
very long (in two parts, totalling nearly 1000 lines) public post (in
SCUBA-L last year) detailing (and explaining) why there were numerous
"errors" made by the NEMESIS-PRO, and asked for public or private
response to those points but received none from Mr. Cochran, and
unsatisfactory answers from his staff. So, I'll state from the start
that I am NOT here to give testimony on how wonderful the NEMESIS family
of computers is. On the other hand, I am NOT here to rehash complaints
about what appears to be now an obsolete product either, the
NEMESIS-PRO, which less than 9 months ago was touted in UNDERWATER USA
ads as heavily as now the NEMESIS II line is.
I am here to ask some NEW QUESTIONS based on Mr. Cochran's present
posting. My questions are confined to the STANDARD NEMESIS II:
1. What's really NEW in NEMESIS II (over the previous generation NEMESIS
PRO)? To re-quote,
> NEMESIS II also figures temperature, breathing rate, ascent rate, and
> reverse profiles into the decompression calculations.
But those were ALREADY features in the NEMESIS PRO, and I had
previously carefully explained why the NEMESIS PRO made gross errors
(including a 54-minute ERROR in its diagnosed deco obligations) in
its decompression calculations.
2. To be explicit, is the decompression calculations in the NEMESIS II
based on a different algorithm or the same as that used in the
NEMESIS PRO (assuming the same aggressive/conservative settings) ?
If not, how are the algorithms different?
3. "NEMESIS II also figures ... reverse profiles into decompression
calculatons". HOW? Is the algorithm based on the result of any
published study (on how to incorporate reverse profile info into
NEMESIS II's deco calculations)? If so, can you point us to one
or more such scientific studies (empirical, statistical, or
otherwise) or a published class of algorithms that can be used to
to figure deco obligations (QUANTITATIVELY) as a function of "reverse
profile".
4. How is a "reverse profile" DEFINED or QUANTIFIED to enable its use
as CONTINUOUS INPUT (I presume, given the multilevel profiles of
many computer divers) to CONTINUOUSLY UPDATE the deco-obligation
schedule diagnosed by the NEMESIS II ?
5. Would my dive profile (which was the 2nd dive of the day on the
2nd dive day on the Cayman Aggressor, after a 15+ hour surface
interval overnight), a CLEARLY NO DECO dive in my book and my
other computers, be diagnosed as one with a MISSED 52 minute deco
on the NEMESIS II ? (Mr. Cochran has complete second-by-second
records of those dives from my personal disk returned to him).
If not, what would be the diagnosis under NEMESIS II ?
That should do for a starter. Thank you Mr. Cochran, for your offer
to ask for more info, and I thank you in advance, and eagerly look forward
to, your answers to the above questions.
Regards,
-- Bob Ling (aka Reef Fish (Large Nassau Grouper)) RFLNG@cl*.ed*
Ph.D. and Fellow of the American Statistical Association.
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