Fabio Moretzsohn wrote:
> I took a quick glance at the article on rebreathers and thought it was
> nice. I guess I missed the part about the price, but if it is "just"
> US$6,000, it may be out of reach for the masses, but it is more
> affordable than previous models.
>
> And again, I may have missed the working (or maximum) depth that this
> model can work at. A friend of mine from Hawaii, Rich Pyle, has been
> diving and helping develop rebreathers in the past 15 (20?) years. I
> don't recall the brand of rebreather that Rich uses, but I do know that
> he can dive up to about 500 ft (about 150 m), and stay for a long time -
> as much as several hours depending on the depth. But the whole equipment
> and personnel support is very expensive, as is training (in the order of
> $10,000).

Pyle uses CIS-Lunar CCRs running tri-mix. CIS-Lunar has changed hands a
few times, and I don't know if Poseidon now owns it or is just
making/marketing the Discovery. The Discovery runs air (technically,
nitrox) which is why the relatively shallow max operating depth.
>
> Rich is an ichthyologist and he likes to dive in what he calls 'the
> twilight zone", which is deeper than scuba depths (about 40 m maximum)
> and shallower than the depths visited by research submarines. Rich and
> his colleagues have discovered and named many new species of fishes.
>
> Rebreathers started to be developed in the 1940's, but until recently
> (say 20 years) it was only available to civilians.

Actually, rebreathers for scuba go back to the mid-1800s (Sicard) They
were commercially produced for use in mines and smoke, but were not
commercially successful in underwater work until the Fleuss designs of
the 1880s were developed by Siebe-Gorman. The underwater work in Jules
Verne's "20,000 Leagues Under the Sea" (1870) was done with
Rouquayrol-Denayrouze compressed air/demand regulator scuba (which was
then commercially available), but the film (1916) was  shot using
Hall-Rees rebreathers, as were subsequent Williamson underwater films
The Submarine Eye (1917), Girl of the Sea (1920), and Wet Gold (1921).

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