"Gary" wrote in message
news:tS%gf.578681$oW2.415490@pd7tw1no...
News f2s wrote:

What happens is that as you go deeper it becomes progressively
more difficult to breath in, because your lung pressure is at
atmospheric, whilst the water pressure is increasing at about
half a pound per square inch for each foot of depth.

Duh! Of course if the hose is reinforced and more rigid than
your chest walls the you could get squeezed if you are not smart
enough to hold your breath.

Gary, you also get squeezed if you hold your breath, though
slightly less.

This limits me to a depth of about 4 - 5ft. Any deeper and I
have a coughing fit after re-surfacing. Apparently that's
caused by bits of the lungs collapsing, and the coughing is a
reaction to the little subchambers unsticking again. Nasty
feeling.

The air needs to be pumped down at the ambient pressure of your
lungs. After a couple feet *most* people can't suck hard enough
to get air. You might be the exception.

We *were* talking about using a breathing pipe to inhale
uncompressed air. I've tried this, and found a technique that
allows me to breathe under a shallow hull, using a long pipe, just
a little deeper than with a snorkel. I don't recommend it. And
yes, I do have a tough rib cage. And yes, I hold my breath to go
temporarily deeper, and I do the breathing cycle at the shallowest
depth possible, and I usually work upside down - hands at 4ft and
lungs at 2ft. All of which makes it possible to work around a prop
wrapped with a fishing net without getting the tanks out.

However, there are serious hazards in playing this game without a
great deal of care, practice and preparation. Since you obviously
have enough under water experience to make rather patronising
comments, I'm sure you appreciate this.

JimB