[pct-l] RE: Bivy

[calliger at infolane.com (Richard)]

Bivy, in my experience of one month does not keep you any warmer than a
tent does...it keep the night breeze/wind off you is about all. At .1 mm
thick there is no insulative value in either a tent or bivy per se. Any 
heat trapped in via warmed air is de minimus as the rate of themral
conductivity out of the tent is about equal to whatever heat souce one
is putting into the tent. Hence there is no warmth retained per se.
The value and warmth that is achieved is from the lack of air flow
carring heat out. There still is conduction that "sucks" out the
heat attempting to be retained from the warming of the interior air.

Richard
At 10:39 AM 9/7/2004 -0700, Griffith, Paul C wrote:
>Consider the combination of a very light bivy and a poncho/tarp.  Google
"Equinox bivy" for reviews and ads for a 6.5oz bivy bag.  Combine it with a
7oz poncho/tarp for a total weight of 1 pound with a few light stakes.  If
you don't expect heavy rain, just use the bivy and save the effort of
rigging the poncho/tarp.  The bivy makes you sleep warmer, so you can carry
a lighter sleeping bag or quilt. The poncho replaces your rain gear, gives
you extra protection for heavy rains, and a tarp to sit and cook under.  The
bivy protects you from rain blowing under your little tarp.  And, if you
manage to lose one, you can survive with the other.  I've never had problems
with condensation in a water proof/breathable bivy.  I used a home-made
one-piece poncho/tarp/bivy in the Sierras last year, and a 5x8 tarp through
the Cascades.  The light bivy combined with a poncho would be twice the
protection I had.  Long rainy spells are best spent in a motel. :-)
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