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On Mon, 03 Nov 2003 11:48:30 -0800,
Lloyd Sumpter wrote:
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


There are two problems.

1) Unless you have a seperate exhaust path (usually via a valve directly
into the water) you can't push the "bad" air, out of the snorkle very
far. If the volume of the snorkel tube is a significant fraction of your
lung volume, you just pusþ the air up the tube, and then draw that same
air, back into your lungs.

2) The pressure at say, 7 feet depth, is about 1.5 atmospheres, so you
will be drawing in 1 atmos air, against 1.5 atmos pressure on your
lungs. Try it. Take a garden hose down to 7 feet, with the other end in
the air, (of course, keeping the water out of it) and try taking a
breath through it. You will be able to do it, for a while, maybe a
minute, by exhaling through your nose, but you'll give your diaphram a
real workout.

The usual solution, is either a tank+reg with a really long hose in
between or a hookah setup. The tank's a lot cheaper, especially if
you allready have the tank and the regulator, the hose isn't too
expensive.


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--
Jim Richardson http://www.eskimo.com/~warlock
"What I look forward to is continued immaturity followed by death."
-- Dave Barry