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David Story writes: >Keir Vaughan Taylor writes: >> >> The premise is that all dive tables have a certain bend >> percentage, e.g. American Navy tables at 5% >Where did you find this figure? I suspect Keir got this figure from the same place that (many) people (seem) to, just sort of an incomplete telling of the US Navy tables history. To quote Lippman (without permission) _Deeper into Diving_ pg 215. "At their acceptance trials in 1956, the schedules [USN tables] produced and overall bends rate of 4.6%..." and now the important part.. "... The schedules on which the bends occurred were then recalculated and tested again (involving very few tests) until no bends occurred. All schedules were then re-calculated in accordance to these modifications." Lippman goes on to say that a 4.9% bends rate was found in the repetitive schedules but he was unsure as to whether these schedules were also re-calculated. For this latter info Lippmann cites Thalmann, Butler (1983) "A procedure for doing multiple level dives on Air using repetitive groups" US Navy Experimental Diving Unit report no. 13-83 and Des Granges, (1957) "Repetitive Diving Decompression Tables". US Navy Experimental Diving Unit report no. 6-57. so it appears that a 5% bends rate on single dives by USN tables is an "urban lengend", but I am unsure what statements can be made about repetitive dives on USN tables. Perhaps someone can shed more light on this. Personally I always say that tables don't grant "permission" to do certain profiles, they just provide guidelines. It's a give and take. If you "take" by pushing to the table limits, "give" a little back with additional time on the safety and/or deco stops. Hope this all helps more than it confuses, Mike PS. One of the more popular scuba rags had the 5% USN DCS rate listed in their "diving myths" section. PPS. Sorry to add several more references to the recent flurry. The (inevitable) on-line access to all of these refs sure will be nice one day... -- Mike Zimmerman zimmmt@au*.al*.co* PADI AOW/deep/drift My opinions, not Alcatel's "make me an informed fool, not an ignorant one"
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