Dan Mitchell describes a couple days in the Sierra in which he was obliged to ride out a rain shower in the close confines of a bivy sack. He also had to figure out how one inserts one’s wet body into a dry sack, to wit:
A couple minutes later it was raining enough that I had to stop and put a rain cover on my camera bag. As I dropped through a steeper section of the route between the middle and upper lake I realized that I was starting to get significantly wet. I found a partially fallen tree that provided shelter until the rain slacked off a bit, and then continued on for another 15-20 minutes in the drizzle to reach my campsite.
Fortunately, I had zipped my bivy up tight, so my camp was secure and dry. Now I had the opportunity to figure out how to try to keep it that way while getting out of wet clothes and into the bivy. It went something like this: Take boots off and stuff them into a large plastic bag along with pack and few other odds and ends. Move food canister close to bivy in case rain continues during dinner. Open bivy and push sleeping bag away from the opening. Standing in the opening of the bivy, quickly put on additional poly layers and put the damp pants and shirt on over them. Zip into the bivy while lying on top of the sleeping bag and let body heat do its work of drying the damp clothes. Listen to thunder and rain and hail on the bivy. When rain stops, sit up in bivy and fix dinner — and then zip up again for after-dinner showers.
I used a bivy on the White Mountain outing and had something interesting happen: In the middle of the night I noticed a bunch of condensation on the inside, confined mainly to one side (hey, I need something to keep my mind occupied while I’m lying there pretending to sleep for nine hours.) Then I noticed my sleeping bag was half open on the same side and I realized the body heat escaping my bag was causing the condensation. After I zipped up, it seemed to dry up a bit.
Something else I learned on this outing: you need to know alternative tarp pitches before you’re standing on a broad saddle between hills with 30 mph winds gusting through. You really need to know your knots and pitches by heart or you’ll just be casting about in the wind driving yourself nuts.
(The more I experience camping with alternatives to tents, the better tents look).