I am considering getting a bivy but have a few questions about them. 1) I've read that they can add a few degrees to ones sleeping bag. (I've read anywhere from 5 to 15 degrees warmer.) Has anyone had any experience noticing any improvement with a bivy improving the warmth? 2) If I am using a sleeping bag liner already, will I still get any warming benefit from the bivy? 3)I've noticed on a lot of sites (REI, etc.) that condensation is listed as one of the problems with bivies. I've also noticed that most of these complaints come from the regular size models and not the large. Does the extra space of a large bivy help cut down on condensation?

Let's go

1. No more that a couple - few degrees warmer. You would be better off wearing a dry thermal base layer to bed
2. Yes, same amount as #1
3. Don't count on stopping condensation by buying a large sized bivy unless the bivy is a double wall tent. Exception, if the bivy is not water proof or water resistant, but then what good is it?

I have a bivy made with Epic and still have condensation issues in the wrong conditions, which is most of the time in the southeast. It is not my most used gear. There are better uses for money.

Egads

As Egads said.

I have a waterproof bag (at least the bottom part is....) which works fine with my bivy. That said, I primarily use it for sleeping out on my boat's nets. There's a lot of condensation out there, mostly outside the bivy.

The bivy is heavier than a tarp tent, by a fair bit. It has less ventilation and less room for clothes and stuff, there's no room for a pack. On a trail, take the tent; on the boat, mine anyway, use the bivy.

When I'm not in it, I keep the sleeping bag and pad in the bivy. Good protection for the sleeping bag, although it doesn't get much of a chance to air out until I get home.

Thanks for the information. I think I'll stick with my tent for now. I will keep on the lookout for lightening packweight, though. Bivy, maybe someday. Just not anytime soon.