From: njs@scifi.uucp (Nicholas J. Simicich)
Subject: Re: computer recomendations?
Organization: Nick Simicich, Peekskill, NY
Date: Sun, 23 Aug 1992 23:19:40 GMT

In article <9208211735.AA18890@shogun.smos.com> joseph@shogun.smos.com (Joseph Crunk) writes:
>
> 
># > I was at 170fsw, unusually well narced, when the computer began
># > flashing at me.  I noticed the light and picked up the computer to
># > figure out what it was saying.  Now realize that I've got 200+ dives
># > with my Delphi, both no- and decompression diving, and have seen
># > almost every mode (except ERROR, thank goodness!) that it has in it,
># > AND I'm a computer geek to boot. 
>
># Yes, I seem to have lucked out on the unit that I have as well. It's a
># Pro, that's been on well over 150 dives at this point, many of them deep
># (the deepest was to *****CENSORED*****, and believe me, having those big
># digits and easy to read display makes a big difference when you're
># *_HEAVILY_* narc'd).
>
>CAUTION! Your (mine, and everyone elses) computer is rated to a given depth
>by the manufacturer. This depth is the deepest that computer is KNOWN to
>function. Taking it below that depth may result in incorrect decompression
>calculations as well as incorrect depth sensing. For this reason, depending
>on a computer taken to *****CENSORED***** depth can be a really dangerous
>thing to do. I'd use every caution when even approaching the rated depth.
>
>Note: most computers are rated for a depth in excess of 130 fsw. I'd have to
>look it up but I think the Delphi was rated to either 190 or 200 ft. In the
>book 'Deep Diving' Gilliam notes that an Aladin accurately calculated the
>depth in excess of 500 fsw, altho it's rated to 330 fsw. Your computer's
>mileage may vary.

The Delphi, in particular, was rated to 200 feet, while the Delphi Pro
was rated to 300 feet.  Manufacturer's representatives informed me
that the Delphi was actually the same internally as the Pro, with the
exception of the fact that *the display driver* was hosed to display
'or' (for out of range) for any depth deeper than 200 feet.  I tested
mine significantly deeper than that, and then dumped it, and it did,
in fact, accurately track depths down to 280 (I've never been that
deep, this was done in a test chamber).

>Also, there's no military, scientific, or commercial applications for diving
>when you're *_HEAVILY_* narc'd. I'd be hard pressed to find a sports diving
>application, other than pure entertainment :-) All-in-all, this kind of 
>diving is a little to close to the edge for my comfort.

Here, I agree.  But degree of narcosis is quite damn hard to predict,
dive to dive.  Dave's post highlighted to me exactly why I teach that
divers must be very experienced before diving at narcosis depths.
Although a very experienced diver, and reliable on the (2) dives we
did together, and also experienced at these depths, Dave suffered a
common symptom of extreme narcosis, instrument fixation.  Had he not
been an experienced diver, he might not have been able to recover from
this at all.

My personal belief is that we all get narc'd from time to time,
including Navy divers who do dive on air in those ranges.  However,
their procedures are so different that fixation on the task at hand
may well be a positive thing, not a negative.


-- 
Nick Simicich - uunet!bywater!scifi!njs - njs@watson.ibm.com
SSI #AOWI 3958, HSA 318, NAUI #14065
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