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At 06:15 AM 10/11/00 -0400, Trey wrote: >Kent,come on - one hour at 85? On 21% that is barely a deco dive to start >with. Why would one want to red line the ppo2 to shave a few minutes off of >what they "think" the deco really is? That is pretty piss poor risk >management, and basically clam stupid. I never do that , and the fact is I >do longer cave dives than anyone out there as a matter of routine. Cobb is >right on the money here. The risk is in the exposure, not DCS , and for more >DCS coverage, the deco can be redone - the tox can not be redone, and the >pulmonary damage of an exposure to red-lined ppo2's takes several weeks to >fix. The main problem, as I see it, is the rec community's insistence on "no-stop". I played with the hot trimix concept on several dive planners and found it pretty hard to avoid deco. In fact, I'd much rather keep doing what I do -- bring a small stage with deco gas and accept a 5 - 15 min deco. But then, you can't sell this to mainstream sport diving since any deco is THE thing to avoid. I remember in the early 90s when nitrox was new to most of us. We did PO2s of 1.6 to avoid deco and I soon found that it was better to go a lower oxygen bottom mix and accept a few minutes of deco. Thus, the "hot" nitrox was replaced by a lighter blend and we carried deco stages instead. One might think that a no-stop dive of EAN 40 to 100' gives an oxygen stress similar to EAN 30 at 100' + the EAN 50/oxygen deco required but it doesn't feel that way. A high bottom PO2 gives shortness of breath and a tense feeling if there's any work involved while a high PO2 for deco is no problem. There's more to this than summing up OTU numbers. As long as sport diving thinks of deco as an emergency rather than as a safe landing there will be an incentive to "up" the oxygen of bottom mixes. regards, Hans -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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