Tarp without a bivy?

I used to have a Beeline, and I think the Pertex shell is pretty water resistant. If worrying about a wet bag is keeping you awake, a bivy should be the hot ticket. I keep looking at the Equinox bivy, which should be good for sleeping under a tarp and getting splashed. Those bivys are $60 and 6.5 oz.

I work for a guiding operation that uses tarps exclusively, year round. Clients are not issues bivies. I carry one during the winter.

One can stay dry under a tarp easily, provided that the tarp is actually waterproof and offers sufficient coverage. When it snows however, I find great luxury in a bivy. Mostly, I like that I can zip up and stop wind blown snow from hitting my face. It also keeps my bag drier. Though there are condensation issues which lead to wet bags anyways. Last week we had a five day long snowstorm (dropped 1.5 feet of snow) and my down bag got somewhat wet from sitting in the bivy but it was drier than the non-bivy user's bags.

For rain, I don't think that a bivy is important. I'd rather carry the weight in the form of a larger coverage tarp (if your coverage area is minimal) or a heavier duty fabric (if it's waterproofness is marginal like old or poor quality silnylon).

bivy advantages:

1) bug protection
2) increased "splash" protection
3) the ability to use a smaller, hence lighter tarp(see #2)
4) The option of not setting up the tarp at all if not needed
5) wind protection (from under the tarp)

– number 3 is not a real advantage on its own because of the added weight of the bivy itself.

and some more:
6) keeping moonlight out of the eyes
7) it's warmer
8) keeps your stuff drier and more organized in a snow storm

I guess the trick will be to test it out a few more times in rain. Hopefully this spring… and then I can decide on what to do next.

So is the condensation on the inside of the bivy really significant? I've never used one at all, but it's also been so long since I've used a walled tent that I haven't had any condensation problems in a while.

It looks like another thread on "which tarp to buy" just started in another forum, which was going to be my next question. Thanks for the useful info.

The bivi allows for a lighter sleeping bag, so you can still stay with a really light sleep system.

I worked for NOLS where we used tarps for decades – an we never used bivy sacks, and it was fine.

Good point, Mike. A semester at NOLS is where I decided to go with a tarp in the first place, as well as where I first heard of you and your illustrations. NOLS seemed to discourage down sleeping bags a lot when I was there four years ago, probably because winter expeditions and wet down do not mix very well. Just an extra precaution they took? I'm still cautious to the point of paranoia with my down sleeping bag, hence the sleepless nights.

So it sounds like winter tarping and tarping under a small tarp call for bivies more than a big ol' tarp. Any times when a bivy is a definite no-no?