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Hi John: > > In the ScubaPro '95 catalog they advertise the DC-12 Dive Computer > and state that it's based on Max Hahn's P6 algorithms which > "utilizes both dissolved gas and bubble mechanics". Nothing is > said about Doppler testing. It's funny, with all of the MK 10/G250s and other excellent ScubaPro products that the deco diving public uses, I've NEVER seen a DC-12 setting the stops.... So, what's going on here? Here's my warped version of pure, unsubstantiated rumor: References to bubble mechanics being involved in the DC-12's algorithm are pure marketing BS. In the early '90s, S.Pro-USA worked with Wienke to develop a bubble model-based computer that would use his RGBM (the RGBM extends Yount's VPM to repetitive dives). Business (rather than technical) "difficulties" prevented production of a product. Meanwhile, S.Pro-Europe wanted to go with Hahn's P-6 (no Buhlmann involvement) for the next generation computer. So, a 50/50 compromise was reached.... The bubble model stuff was used for ads, marketing, etc, while a "traditional" supersaturation algorithm set the stops. As far as I'm aware, no bubble-calculated schedules are publicly available. Wienke was involved in developing recent versions of the Abyss desk-top-deco software product. Although I don't own Abyss, I know that it does not use the full iterative calculation scheme required to calculate VPM schedules and that for a single dive it does not produce a bubble-like ascent. To wit: Reference aquaCORPS #10 article "MATTERHORN." Therein is detailed a multilevel dive and a deco schedule calculated by Abyss. (Please jump in Chris!) As best as I can make out it goes like this: DEPTH(ft.) RUN-TIME(min) -------------------------- Dive on Air Descent 3 200 13 160 26 130 37 Stops on air 40 41 30 50 Stops on O2 20 58 10 75 0 76 Yount's VPM algorithm (as detailed in Yount&Hoffman 1986) Produces the following schedule: Depth(ft) RUN-TIME (min) -------------------------------- Descent 3 200 13 160 26 130 37 Stops on air 80 41 70 44 60 47 50 53 40 61 30 70 Stops on O2 20 77 10 87 0 88 Note that the VPM starts your stops much deeper than Abyss and gets you out of the water a bit later (the Abyss schedule seems a bit aggressive). This isn't to say one way is good or bad...hell, neither the VPM or most desk-ware has been "tested," so watch out, be careful, etc--but mostly be critical! Regards EM _____________________________________________________________ Eric Maiken email: ebmaiken@ea*.oa*.uc*.ed* Dept. of Physics o: 714 824-6621 U. of California fax: 714 824-2174 Irvine, CA 92715-4575
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