How much air in your BC?

[Hatul]

I'm actually fairly sure that I can dump faster from my rear dump than from my inflator hose, and in fact, tech divers are often taught that, in the face of a runaway inflator, the rear dump should be used for that reason.

Hi,
What I meant in my post about efficiency is not the rate at which the air vents from an inflated BC, which is normally not an issue, but getting the last bit of air out of the BC. This is important for fine buoyancy/trim control, minimizing the amount lead you need to carry, and to some extent air consumption.

The reason for this: if you raise the inflator hose above the bladder of the BC you get a pressure difference pushing on the air in the BC, from the height difference. It's a foot or a little more of sea water positive pressure pushing the air out, which you don't get just by opening a vent on the bladder. It's a way of getting trapped air out of the BC,

Adam

 

[dive_gorilla]

keep in mind the difference in buoyancy is still equal to the weight of the air used, whether the cylinder is steel or aluminum.

This hit it right on the head. Thanks Steve for simplifying it even more.

 

[Nemrod]

Another point relevant to this discussion is that it's more efficient to dump air from the inflator hose pointing up than from all the dump valves on the bladder, especially if the BC is prone to air trapping.

Adam

If there is any air in my wing to dump, then I use the rear dump 90% of the time.

N