eVent bivy + down sleeping bag

Dave – I have never had a problem, even on the very wet west coast. Perhaps over a trip longer than a week there will be some slow migration of condensation inside the down bag, but I have never had a noticeable issue. You will get some indicating that 'Technically speaking…' but I don't rely on that – it is what occurs in the field that is most important to me.

You won't be zipping that bivy shelter up all the way anyway. The awning allows the bivy to be opened.

Dave,

You will be fine with the down bag in the eVent bivy.

The biggest issue to deal with hopefully having a little bit of sunlight in the daytime to lay out your bag to dry off any possible condensation that accumulates on the top of your sleeping bag shell.

Heck, your own body heat might be sufficient over time to dry off any minor wetting from condensation.

This past weekend, I was with some friends at Mt. Whitney's Trail Camp (12k ft) and we were rained on for 12 to 13 hours.

I was using a MLD Poncho Tarp, MLD eVent Soul Side Zip, and Marmot Helium EQ Down 15 F Bag.

I was easily able to stay warm and dry the whole time….even after having to relocate all of our shelters in the rain after we found out at 1 in the morning that we were sleeping in a rain runoff ditch.

I was even able to crawl in to sleeping bag with damp clothing and my body heat dried off all the gear without collapsing my down bag's loft.

Anyway, my experience and result was that I had a minor amount of condensation on the surface of my bag….the amount of condensation really is a function of dew point.

In the 1.5 yrs that I have had my eVent bivy, the condensation was nothing so bad that 20 minutes of sunlight could not dry off.

MLD's Momentum fabric, which is standard on all their bivies is more breathable vs. eVent, but if you want bomber….eVent is the way to go.

P.S. When I bought my bivy, I was very paranoid about getting my down bag wet, as I have had the experience of sleeping in a wet down bag and shivering all night. My Marmot bag also has a waterproof shell and I have seam sealed it to. I guess I am really paranoid. :)

-Tony

Works great together! Far better then a regular bivy. Only possible issue is that sometimes, even when my head is zipped out of the bivy, near where I've been breathing the down is wet. The eVent is so breathable that my warm moist breath can travel back through the shell and wet my bag. Have not had that happen with a Tege-Tex bivy. Just a FYI, otherwise they are awesome

I have used a variety of down bags and bivies since my first in 1969, all over B.C. and for some extended periods, including in winter.

To me, a GOOD down bag and an eVENT bivy, with a good pad, are THE most comfy and enjoyable tools for snoozin' in the bush.

Integral Designs consistently makes the finest bivies I have seen and their down bags are equal to WM and FF and close to Valandre; a combo of the two plus an Exped pad or maybe the new NeoAir oughta make your bones comfy.

Just wanted to say a quick thanks to those of you who posted in response to my question. Much appreciated.