Conshelf Supreme first stage?

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rsingler,
By the way, breathing at 50 breaths per minute (BPM) is hyperventilation, and actually reduces oxygenation of the blood. This is because this rate dictates a very shallow breath, and you won't get the exchange needed. The use of 20 breaths per minute by Scubapro is based upon research results for active divers, and is more realistic.

SeaRat

Thanks, SeaRat! Your AIR-1 data was terrific. Luis' points about flow vs. inhalation resistance not being equivalent to a WOB loop are appropriate, but it's still fascinating data.

I just have to comment on the above. 50 bpm is only hyperventilation when it's not driven by demand. The decreases in oxygenation are driven by the pH change in blood from respiratory alkalosis, if you blow off too much CO2 by hyperventilating. The blood oxygenates okay, but can't offload to the tissues as well when the pH is alkaline. There's also some vasoconstriction that happens when CO2 drops. A big deal in neurosurgery.
But in max effort exercise, your CO2 production is huge, and you need to breathe that much to both acquire O2 for your tissues and to blow off CO2 to preserve normal pH (not including whatever lactic acidosis you acquire from anaerobic metabolism by being unable to breathe enough for the exercise load). So in the hypothetical "big Navy diver", my presumption was that he was breathing 50bpm because he had to. Sorry I didn't make that clear.

"Enough for the USN" was really just a cryptic reference to their standards for military regulator testing at extreme depth and max RMV. Again, sorry for not explaining myself. I certainly agree with the risk to the out-of-shape fat guy outstripping his ability to oxygenate his tissues! Long live drift diving! :)

Doc
 
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Doc Rob, at first I did not believe that 50 BPM were possible, and I cited a paper to you in a PM about that, but in the same PM I found this You Tube video of an 800 meter immersion finswimming event, and counted between 40 and 50 BPM. The amazing thing is that the winner swam the race in 5:59.98. Amazing.

https://www.youtube.com/watch?v=RSGpw-ZFWTc

I also note that it appears that the Poseidon regulator was used by at least one contestant. I have a publication comparing the Cyclon 300 with four other regulators, and finding some problems at very low tank pressures (300 psig). The Conshelf XIV, Calypso and A.I.R. 1 on the five port first stage fared well.

SeaRat
 
Doc Rob, at first I did not believe that 50 BPM were possible, and I cited a paper to you in a PM about that, but in the same PM I found this You Tube video of an 800 meter immersion finswimming event, and counted between 40 and 50 BPM. The amazing thing is that the winner swam the race in 5:59.98. Amazing.

https://www.youtube.com/watch?v=RSGpw-ZFWTc

I didn't know this sport existed- bizarre! Although I did a drift dive recently with a some German tourists and they ended up 1/2 mile further downstream, so maybe it was some of these guy's on vacation?
 

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