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> > > >On Wed, 27 Sep 1995, Christopher M. Parrett wrote: > >thanx for the information, chris. > >> >> Problem is, as soon as we introduce the deeper stops, the shallower stops >> begin to change as a result of the extra ongassing/offgassing <G>!! >> > >i assume *change* means: *lengthen?* NO, quite the opposite. As Abyss computes all ongassing/offgassing in real time, the additional time spent at these deep stops often results in the next stop being negated or reduced to some degree, a situation that requires some artificial manipulation to correct. > >but this may be a result of using the buhlmann-like algorithm (no >iteration) and gradients that are set by tissue supersaturation rather >than O2 window. wienke fractions the gradients (or at least he did in his >work a few yrs ago) so that the critical gradients are somewhere in >between the supersaturation Ms and bubble Gs. That is case indeed. because Abyss is a buhlman based system, we must adhere to certain basic principles for the moment. > >when i run vpm code, then plug the deep stops the vpm gives in with a >bottom profile into zhl16-like code. i find only a slight increase in >shallow stop time. sometimes the stops shorten too. > >yount's vpm (non-repetitive diving rgbm) is considered dated >in it's approach to deco modeling. however, one tantalizing aspect of the >schedules produced by the vpm is that they get you out of the water in a >total ascent time less than buhlmann (this is an artifact of yount's >calibrating to the usn assent times). if there is sufficient "truth" in >vpm gradients, then perhaps an optimal model for deco will result. >that is, one that keeps you from getting bent--yet lets you out of the >water in as short a time as possible. The only problem becomes one of emergency gas switches. If you deviate from the anticipated gas regiment, your Screwed Big-Time, as the previous deco stops have now become dependant on the subsequent ones. With the Buhlman system, previous stops are independant of each other. Christopher M. Parrett, President, Abysmal Diving Inc. Makers of ABYSS, Advanced Dive Planning Software. 6595 Odell Place, Suite G. Boulder CO, 80301 Ph, 303-530-7248, Fx, 303-530-2808 ftp://abysmal.com/users/abysmal http://www.emi.net/boynton/abyss/abyss.html
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