Posted by RaiderKarl on June 11, 2001 at 13:02:36:
In Reply to: You mean you have two tanks with one reg each? posted by Maciek on June 11, 2001 at 12:25:59:
soon to be 5 regs, all ScubaPro Mark 20s and S600s. yup, theyre expensive.
but the only thing that is different, to get back to your question, is that you have a separate SPG on each tank when you dont link two of them with a manifold. The number of regs is still the same.
rule of thirds without manifolds: use 1/3 of 1st tank, then switch to 2nd tank, use 1/3 of that, turn around & begin egression using another 1/3 of same tank, then switch back to first tank, use 1/3 of that, then dive should be over. you should have 1/3 full of air in both tanks as your reserve.
If you had to, you could swap out a malfunctioning reg underwater. When you cleared it, you would be running seawater through it. not good, but like I said, if you had to, you could do it in an emergency that you were trying to solve underwater. Thats the main disadvantage I see of not using a manifold, the possible reg flood.
the advantage of a manifold is that it allows to you isolate either a tank or a regulator, and to eliminate one SPG. but it seems like the manifold has weaknesses of its own as a failure point. at least, it seems like it to me. I have dived with manifolds and without them. And I like without them better. Although I am definitely not a cave diver, nor married to GUE/DIR.
Im not recommending this out loud, just saying that a manifold seems to have advantages and disadvantages all of its own.