Posted by tleemay on November 14, 2000 at 14:57:36:
In Reply to: OT, but on the other side of the spectrum, posted by Eins on November 14, 2000 at 13:02:29:
I believe you are expecting too much from the added
air to the suit. The thermal property of a shell
suit (is this what you have?) is governed by the
undergarmet you use. Usually, the thicker the
undergarmet the more thermal protection is afforded.
The trade off is that the added bulk of the
thicker suit adds more airspace between you and
the shell, increasing buoyancy. It does not take
much space between you and the shell to keep the cold
away from your skin. The thicker suit really just
enables you to maintain the heat your body generates
and not let it conduct to the inside of the outter
shell.
Adding air to a shell dry suit to increase warmth
does put additional un-uniform space between you
and the suit, but will cause other problems with
buyancy. You only neeed to add enough air to take
the squeeze off and no more. If you are diving
and the squeeze is not an issue and you are still
cold, you need better thermal protection from
your undergarment, not more air in the suit.
If you were diving cold deep or long with whatever gas,
you will probably need to use argon as the inflation
gas because of it's molecular ability not to conduct
heat away from the body as He, N2 & O2 does. If there
was He in the X gas, the exact opposite would occur
since He conducts heat away from the body. One drysuit
manufacturer says that using argon as an inflation gas
increases warmth as much as 25%.
In my opinion, buy just continuing to add air to the
suit to gain warmth, you will be causing other problems
in the buoyancy department.