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In a message dated 7/25/98 10:04:57 AM Eastern Daylight Time, cobber@ci*.co* writes: > Al, I am always thinking in terms of deco diving. If one aspires to > extend one's bottom time, then you are heading towards deco diving. And > if you want to deco dive and take on the risks that entails then you must > do it right. DIR = doubles, and that's that. > > I look at single tank diving as a transitory phase, something that should > be done with minimum investment of money. Sure streamlining is great, but > to me DIR is using a system, and the system depends on a doubles > configuration. I don't care how you setup a single, you screw up the > system unless you are diving doubles with an isolator manifold. > > IMHO for maximum survival, any dive where a problem can't be resolved by > a one-breath free ascent to the surface should use a doubles setup. Dive > shops should be renting doubles rigs rather than singles for 80'+ dives. > I see guys doing deco diving all the time with a single and a pony. Using > this rig with a backplate and singles wings does not make it right. I Jim, First all diving is decompression diving. All. From a physiological standpoint we know very little, and asserting that it is ok for divers to suck an 80 and blow and go by design is _ wrong _. * I do not think this is your position.* Blow and go is an emegency procedure, and any diver who uses such a plan as a primary needs serious help, in that they have abandoned all their training for luck and instinct. I would suggest that any diver who plans to dive in this manner needs some retraining by a quality instructor, or they need to take up golf. Once a diver has mastered basic scuba, they would greatly enhance their safety and comfort with a DIR style single rig. The reduced drag will allow reduced breathing rates, and if the diver increases their level of conditioning, they will see even more improvement. This diver should be diving in a buddy team and both should have a good handle on their gas consumption rates. Using nitrox for moderate depths, say 90 to 120fsw , they could easily reach or exceed their no deco limits, and do the deco and survive, if they are a disciplined team. They should not violate thirds in open water to have all the redundancy they need < long hoses >, and would be able to do it faster cleaner and simpler than two divers with iso doubles. Now if you have a long deco exposure in mind iso doubles are far superior to single/pony rigs. Too many divers use the pony as a smaller additional tank. This is also wrong. The pony should be only for an emergency, but all to often is not. Furthermore divers using this type of rig often have no idea what their sac rate is, or how long their gas will last. The first time i used a pony I let it get me into a place I had no business being, and i survived because I am lucky. It took half a dozen more or so similar exposures for me to think, I really need two big tanks. Then I was still diving stupid, only with more crap to haul around. It wasnt till I started to think about optimizing my gear to my plan, that i began to try to DIR, and i am not there yet. Thats why the single will always have a place, and every diver should have a single rig, because there will always be a dive which will require it. This is another reason for standard rigs, because the rig doesnt change much when your doing deep wrecks with doubles one day and shallow reefs with singles the next. Remember : redundancy always comes from the buddy first, then from the gear. regards, Al Marvelli -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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