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> But I don't think that the phase-dynamics model has INVALIDATED the > concept of "accelerated" decompression (pardon me for re-using that term) > by switching inert gases. By the definition you just provided, I don't think it invalidates it either. I also doubt George thinks it invalid, but I'll let him state his own opinion. I might have missed what originally launched this dialogue, but my initial reaction to you was to suggest that the "real" decompression cost of breathing the bottom mix instead of the intermediate mix during the deep stop might not be as great as you seemed to make it out to be. I don't know what George said to suggest a gear configuration (or whatever) that might lead to breathing bottom gas on the initial deco stops; but knowing his insight into what works in rig configurations, I'd be willing to bet that the benefits of such a system would outweigh the costs, if the cost was merely to breathe bottom gas instead of deco gas on the initial stops. > It seems to me, as if you're proposing even more "conservative" > decompression - while George considers the tables by John Crea for > deco-weenies. So I'm not quite sure which view you're supporting or if > you're kind of between the chairs and doing your own thing altogether From previous posts, I know that George shares my recognition of the value of deep stops. I suspect he does not like John Crea's tables because they require very long shallow stops. I believe the shallow stops need not be so long in duration if the deep "safety" stops are incorporated, but unlike George I prefer to do the long hangs in shallow water anyway. The reason for this is that, also unlike George, I nearly gave up my ability to walk permanently because of a bout with blood bubbles. George thinks the long O2 stops can be harmful because of the big O2 doses. Although I don't have as great a concern of this as he does, I recognize its foundation. > Who does your tables or which software do you use? For OC mixed gas diving I used to use ProPlanner. For rebreather diving, I now use DCAP. In both cases, I modify the schedule by including one to three additional deep stops before my first "required" stop. These are generally about 2 minutes in duration; the first is done halfway between the bottom and the first required stop, the second is done at half the remaining distance, and the third is done at half of that remaining distance. This method evolves depending on the particulars of the dive - sometimes I use 2/3 the distance; sometimes I use 1/3 the distance. The point is to break up the long direct ascents - just like traditional "safety stops" used in no-decompression diving (as if there was such a thing). > How does your total > decompression time compare to someone using a modified Buehlmann algorithm? I'm not sure - has anyone ever used modified Buhlmann models to do constant PO2, constant PN2 trimix dives? That's the gas I breathe now. In any case, I'm probably in the water longer than most folks breathing the same mixes, because another of my modifications is an additional 15-45 minutes at 20 feet on 1.4 ATA O2 beyond "clearing" the required deco at 20 feet on 1.4 ATA O2. The cost of this is huge O2 exposures. "Air breaks" help, but maybe they don't help enough. It's a precarious balance between O2 problems and DCI problems. Neither seem very friendly to me, but having seen the wrath of DCI first hand, I tend to lean away from that more. On the other hand, O2 can be more insidious - I hope never to cross that one first hand. Aloha, Rich Richard Pyle deepreef@bi*.bi*.ha*.or* ******************************************************************* "WHATEVER happens to you when you willingly go underwater is COMPLETELY and ENTIRELY your own responsibility! If you cannot accept this responsibility, stay out of the water!" *******************************************************************
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