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JR Oldroyd writes:
> Who did you do it with? Tom, perhaps, or Dustin? I was down in
> Branford only about 6 weeks ago, at Dustin's. I did Technical
> Nitrox while I was there. Good class. I enjoyed it a lot.
I did a nitrox class with Dustin. My trimix class was with Steve
Berman. I would recommend either of them. It would be great to take
a class with Tom Mount, though his classes are more expensive, in
part because (I believe) he does the dives in open water, requiring
a boat.
> ... Spent a
> lot of time in Little River; also did Peacock, and Devil's Eye and
> Ear. (Talking of which, which of the two is Devil's Eye, and which
> is the Ear - do you know, Bill?)
I find this confusing, too, but I'm pretty sure that the Eye is the
round spring right in front of the steps, off to the side of the river.
The Ear is the fissure which is out in the river. Great cave, as are
Little River and Peacock.
> Anyway, some comments about
> your class would be of great interest. Particularly about the
> instruction you received.
It was a three day class. The first day we did classroom stuff,
basic volume calculations, partial pressures, etc. in the morning.
This was done at Ginnie Springs. Then we drove a couple of hours
south to do a deep air dive at Ward Sink. Although we didn't need
them we carried two stage bottles to get used to that. (My buddy
hadn't done any stage diving before.) Max depth was about 190
feet. We also did a bunch of calculations on making mix, OTUs,
and gas requirements. The next two days we dove at Eagle's Nest,
with a max depth of about 240 feet each time. (As I said before,
there was an error in the mix because someone topped off tanks
which were already filled. Otherwise we would have gone deeper
the second day.) For about 30 minutes of bottom time this took
about 100+ minutes of decompression, using 36% trimix from 110
to 30 and O_2 at 20 and 10. The tables we used were Key West
Consortium tables, based on Hamilton's. These tables are based
only on the fraction of O_2, and can be used with any fraction
of helium from 17% to 50%. Hence they are conservative for mixes
on the low end of the helium fraction.
The mixes we used for the class were 17/17 ("poor man's mixed",
made without adding oxygen) for the first dive and 17/33 for the
second dive. The reason we got messed up on the second mix was that
we calculated 2700 psi in double 104s would be plenty for the dive we
planned. So we mixed that up late at night after getting back from
the first dive. We left the tanks at the fill station over night,
planning to finish topping off the nitrox bottles and analyze first
thing in the morning. An employee came in before we got there in
the morning, and finding these tanks with only 2700 psi in them
he decided to give them a regular cave fill. In retrospect we
should have labeled the tanks. Fortunately final analysis caught
the error, but too late to fix it.
The class cost $400, including all the gas, book (Gilliam and Mount's
"Mixed Gas Diving"), admission to Ward Sink, and certification.
> ...What I'm thinking
> is that if we can find several people who want one, we may be
> able to bulk order and get a great price. I can already get the
> MinOX for about $325ish, or the Teledyne for $395 (both list
> prices). With a bit of negociation, and with the weight of
> a bulk purchase, we may save ourselves some money here. Now,
> I'm not familiar with the Teledyne. Do you have any recommendations?
I'm not familiar with Teledyne, either. The MiniOx is much more popular,
probably because of the lower price. I've heard that Divers Supply has
them for around $300. List price, according to a medical supply company
I called to check, is much higher. I would definitely be interested in
a group purchase to get the best price possible.
Bill Mayne
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