PfcAJ
Contributor
OK, so what do you consider a "balanced rig" in 23C-27C waters, when all that are available locally are AL80s [and maybe AL40s . . . or maybe not] for divers who use wetsuits?
Try swimming up 2x AL80 twins, plus 1x AL80 travel gas bottle, plus 1x AL80 bottle of EAN50, plus 1x AL40 bottle of O2, in a wetsuit, at the beginning of a dive when all cylinders are full -- I doubt you can do it without a lot of effort. I've tried it wearing a full-body 5mm wetsuit plus a 3mm hooded vest. That wasn't enough buoyancy for all 5 full bottles plus me, even though several DIR divers had done a lot of math to advise me about a "balanced rig."
AL bottles are quite buoyant when empty. They're really heavy when there are 5 of them and they're all full. Tech divers need to be adequately weighted, and that's hard to ensure when diving with a lot of AL cylinders while wearing a wetsuit.
If a diver uses a single-bladder wing, it can't hurt to know how to use a bag for redundant buoyancy.
---------- Post added March 25th, 2014 at 02:16 AM ----------
Sorry, let me clarify: I am not at all against a "balanced rig." In fact, I am trying to achieve a balanced rig. It isn't always easy in 3rd World places with limited equipment options.
What I meant to say is that achieving a balanced rig is not always possible . . . and in any case, isn't it a good idea to know some useful techiques one might use in an emergency?
If you're diving with a "travel gas", you're diving a hypoxic back gas. If that's the case, the double al80s are probably positive or at worst ~ neutral. So that's not an issue. The "travel gas" would be something like 35/25, and that too is right at neutral when full. So your negative tanks are 1 al80 of 50% and 1 al40 of oxygen (and that might be neutral unless you're boosting o2).
Ditch your weightbelt and move your flippers. thats how you swim it up.