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Try it using a shallower profile, with an extended bottom time. Last dive I did was 60 minutes on a 150 ft profile using 26/15 in a stage, and 20/25 in my doubles. I did 55 minutes of deco for that dive. I don't have the *exact* deco profile with me here at work, but my deco stops from 70 to 30 ft totaled 25 minutes. Guess what; my 20 ft stop (did not do a 10 ft stop) was only 30 minutes. Bill Lais, E.I. - Engineer II Handex of Florida - Mt. Dora, Fl. 352/735-1800 ext. 166 -----Original Message----- From: Kent Lind [SMTP:Kent.Lind@no*.go*] Sent: Wednesday, March 17, 1999 2:37 PM To: cavers@cavers.com Subject: Re: o2 for ocean deco "Lais, Bill" wrote: > > This has to be a troll, but just in case it's not: > > You're probably going to be breathing the 50/50 deeper than the O2, and > hence you'll consume more gas. I think we learned about this concept in OW1 > if I'm not mistaken. ;-) > Bill Bill, what kind of deco schedules do you run that requires more consumption of 50/50 than O2? Out of curiousity, I ran a sample profile in Abyss of a square profile 20 min. dive to 200' on 19/30 with 50/50 and O2 deco gases. Using a RMV of 0.6 cf/min Abyss came up with deco gas usage as follows: 50/50: 22.3 cf consumed O2: 22.8 cf consumed On a typical deco curve, the shallow O2 stops are so much longer than the deep 50/50 stops that you end up consuming as much or more O2 than 50/50. Of course, a much deeper dive profile might produce different results. But for ocean diving with AL40s the above profile seems pretty realistic. So, I think Ted's question about bottle choice is quite valid, especially given that it's much easier to fill 50/50 to higher pressures and O2 is a more useful gas to have in reserve for surface emergencies. I happen to use two AL 40s for ocean deco but if I was compelled to use different size bottles, I'd chose the larger one for my O2. I can jam 50/50 up to 3000 psi no problem. But I'm very hard pressed to get more than 2000 of O2 into any bottle. Kent Lind Juneau, Alaska
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