Re: [Paddlewise] cold weather clothing

Have followed the meandering discussion of whether to wear something under a
wet suit, and if so, what.  Could be that some focusing on the mechanisms of
heat transfer would help.

1. Conduction:  use materials that do not conduct well.  Wet suit rubber,
and __dry__ fleece/cotton/whatever (so long as it has lots of tiny,
non-linked air spaces) are poor conductors.  Water is not a terrific
conductor, but it's better than air, so any lashup you have that is dry
underneath is better than the same rig wet.  Note:  "wet" suits are touted
as keeping you warm "... because of the thin layer of water."  That's
because all wet suits allow some water in -- so naturally it will be a layer
of water that forms part of the insulating (conducting) layer.  A "...thin
layer of air" underneath would be a better insulator, but no wet suit can
achieve that.

2. Convection:  make it so whatever fluid (air or water) is underneath your
outmost garment can not circulate.  __Anything__ with tiny spaces in it
(fleece, principally, for sea kayakers) will help minimize conduction.  So,
go ahead and wear some fleece under that wet suit -- it will help reduce
convection as well as conduction, even when wet.

3. Circulation (taken here to mean exchange with cold water __outside__ your
wet suit):  pretty simple:  avoid wet suit/bootie/top/headgear arrangements
that allow external water to freely circulate into your wet suit.  a "tight"
wet suit -- as Duane says-- is better than a loose one.  In addition, many
suits have leaky seams.  And, one small rip in the knee will really ruin
that insulating layer.

4. Radiation:  use materials that "reflect" your own heat __back__ to you.
Some of the newer varieties of wet suits tout "titanium" flecks or similar.
A shiny coating of metallized mylar would be better, but so stiff it would
not work.  Upshot:  not much improvement to be gained here.

5. Evaporation (from the surface of the wet suit to surrounding air; note
that evaporation __within the layers under the wet suit__ is negligible, ina
smuch as everything should be at 100% humidity, and there is no gradient of
humidity to drive any __net__ evaporation):  the only option is to select an
exterior material that __sheds__ water, and does not hold it.  Surfers or
yore used wet suits with __rubber__ exteriors (not nylon), for that reason.
Impractical, in my view, because the rubber tears and wears easily.

Bottom line:  Make your wet suit have:  No leaks; close fit; fleece
underneath; titanium (or similar) in the rubber mix.

That leaves out one main variable:  how "wet" your wet suit is inside:  and,
turns out that is moot:  it's gonna be wet from __you__ or the surrounding
water, so if you want to minimize this ....... get a bloody dry suit!

And, that's an entirely different kettle of fish.

--
Dave Kruger
Astoria, OR

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