How do you deal with condensation in your bivy?

peaksandpotatoes · Post by **peaksandpotatoes** » Sat Oct 18, 2014 12:00 am

I love my OR Alpine Bivy. It's light and it is easy to set-up. I use it for all my backpacking and even car camping. However, when temperatures drop too low at night it gets pretty wet inside with condensation, and the soggy sleeping bag makes for a pretty miserable second night, especially if that next night is also cold. I'm thinking about just bringing a towel next time to lay over my sleeping bag. Any thoughts?

gary c. · Post by **gary c.** » Sat Oct 18, 2014 1:21 am

A friend of mine was having the same problem. When the gun show came to the local fair grounds he found what was labeled as an "emergency bivy". What it is actually is just a sack shaped like a sleeping bag made out of the same materiel as an emergency space blanket. He just puts his bag inside of it and the milar keeps the condensation from soaking his bag. He still has some moisture from his body now trapped in the bag but it's not too bad. I would think that just covering your bag with a milar space blanket would be simpler and work better.

Hobbes · Post by **Hobbes** » Sat Oct 18, 2014 9:14 am

Don't use a bivy - it's an obsolete technique for hiking. (It was lifted from climbers in one of the first attempts to develop ultralight hiking methods.) To control condensation, you need separation between you and your wind/rain shield. In other words, a tent or tarp.

Check out what PCT hikers use - they are the ultimate test pilots. 80-90% of the time, they simply cowboy camp sans bivy. The reason is because all new(ish) bags & quilts come with an excellent DWR (durable water repellent) embedded in the fabric. The technology is this area is amazing - basically, water molecules are larger than air. So, they've (that is, the MIC, but it's filtered out to the general public) developed materials and coatings that allow your skin to breath, but still block dew/moisture.

PCTers only put up their shelters in weather. Interesting, a lot of are re-considering the effectiveness of their tarps in favor of free-standing tents like the Big Agnes UL 2. The rationale is this: if you only put up shelter in weather, then it should be designed to withstand weather, right? QED

Here are two interesting reviews by PCTers who have thought about this issue, and describe their own (failed) experiences with tarps in extreme weather conditions:

http://lovelinepct.blogspot.com/2014/10 ... w-and.html" onclick="window.open(this.href);return false;

I saw a ton of traditional pole tents in the vein of the Big Agnes UL. Based on what I saw, they were the most common kind of tent, and the people who carried them seemed to really like them. They appeared to be fast to set up and hikers loved the free-standing function. I was jealous when I saw how they would just set up their tent and then move it around until they found a flat enough spot. The second most common tent I saw was the Zpacks Hexamid. Hikers seemed to like these as well, although, they had difficulty getting the stakes to stay in the ground and complained about them being a bit of a pain to set up.

http://bendbound.wordpress.com/2014/10/ ... -for-2015/" onclick="window.open(this.href);return false;

When I got back from my PCT section hike. I sold my Tarptent Notch and bought the Big Agnes Fly Creek UL2. I have only used it on two trips since my PCT adventure. It sets up way faster than the Notch. It can be moved around to find that “perfect” spot once the poles enabled free-standing mode. I am sold on this 2-1/4 pound tent.

I'm going to stick with my MYOG tarp-tent because it can be set-up at a very low profile and only requires a few guy line stake points. But, it does take longer to set-up, and that definitely something to consider if you need to quickly assemble something while you're tired.

Fly Guy Dave · Post by **Fly Guy Dave** » Sat Oct 18, 2014 12:24 pm

...and welcome to HST, BTW!

AlmostThere · Post by **AlmostThere** » Sun Oct 19, 2014 8:05 pm

gary c. wrote:A friend of mine was having the same problem. When the gun show came to the local fair grounds he found what was labeled as an "emergency bivy". What it is actually is just a sack shaped like a sleeping bag made out of the same materiel as an emergency space blanket. He just puts his bag inside of it and the milar keeps the condensation from soaking his bag. He still has some moisture from his body now trapped in the bag but it's not too bad. I would think that just covering your bag with a milar space blanket would be simpler and work better.

Mylar is not breathable at all. I suspect your friend has a tyvek/Mylar bivy, which also has a way of opening it up to vent it. Either way, tyvek is NOT waterproof, and Mylar isn't breathable - the hybrid (I have one) still manages to have condensation in the right conditions.

gary c. · Post by **gary c.** » Sun Oct 19, 2014 11:12 pm

AT, you are probably right. I'm not sure just what it is made out of. It is a dark color on the outside, maybe camo. The inside is metallic colored and why I just assumed it is all mylar.

AlmostThere · Post by **AlmostThere** » Mon Oct 20, 2014 7:00 am

peaksandpotatoes wrote:I love my OR Alpine Bivy. It's light and it is easy to set-up. I use it for all my backpacking and even car camping. However, when temperatures drop too low at night it gets pretty wet inside with condensation, and the soggy sleeping bag makes for a pretty miserable second night, especially if that next night is also cold. I'm thinking about just bringing a towel next time to lay over my sleeping bag. Any thoughts?

Just imagine waking up with a pound of ice all over your sleeping bag and the inside of the bivy. There is a reason most of the local SAR team started out with bivys and migrated into small tents and tarps....

peaksandpotatoes · Post by **peaksandpotatoes** » Mon Oct 20, 2014 2:14 pm

Thanks for the ideas and the welcome! Looks like maybe it is time to starting saving for a tent.

KathyW · Post by **KathyW** » Mon Oct 20, 2014 2:40 pm

Bivy sacks are great. I've not had too much trouble with condensation on the bivy sacks I've used. The one I have now is made of Event fabric and it has a hoop over the head - it's a Integral Designs (Rab) Unishelter that they don't make anymore. My old bivy was a fabric similar to the fabric used in Bibler tents - no hoop on that one, but there was a wire that kept it off my face. I actually liked that one better than the one with the hoop, but it wore out eventually. Bivy sacks are so easy to use - you can make and break camp pretty quick with a bivy sack. You can also camp just about anywhere with a bivy sack - if you're traveling cross-country where there aren't any ideal tent spots, having a bivy sack makes life easier. If the weather forecast doesn't look great I carry a tent, but when it looks like it will be mostly clear I'll pack the bivy.

I may be obsolete, but bivy sacks are not. Tents are not obsolete either. As far as tents, if it isn't free-standing I don't want to mess with it. I've never seen a free-standing tarp, but maybe I'm not up-to-date on the latest ones on the market. I've seen those tents/tarps that use a hiking pole for support - I don't get those ones because if you basecamp with one of those, you'll have to head off on your day trips without the pole(s).

Post by **markskor** » Mon Oct 20, 2014 3:08 pm

With all due respect, must disagree -

KathyW wrote:Bivy sacks are great...

Until you get stuck all day in the rain...can't sit up/ turn over...getting wet by just touching the sides - Too confining for me.

KathyW wrote: Bivy sacks are so easy to use - you can make and break camp pretty quick with a bivy sack. You can also camp just about anywhere with a bivy sack - if you're traveling cross-country where there aren't any ideal tent spots, having a bivy sack makes life easier. ...

Not true in my experience...Packing up a damp, soaked-through bivy - or waiting around till it dries makes breaking camp, for me anyway, a longer wait than just cramming my tarptent in a side pocket...ground cloth only has to then dry...and that folds up small...last thing that goes in my pack.

KathyW wrote:If the weather forecast doesn't look great I carry a tent, but when it looks like it will be mostly clear I'll pack the bivy...

Most of my hikes are in the 10 day - 2-week variety...Sierra weather can change daily. What then? Additionally, I use my tent for bug protection mostly in the early season...can get hot and clammy escaping bugs in a bivy.

KathyW wrote: As far as tents, if it isn't free-standing I don't want to mess with it.

IMHO, all tents need stakes...the old vestibule thing.
BTW, What do you call a free-standing tent that is not staked out?...a kite.

As always, hike your own hike. If a bivy works for you, Great!
...but for me...no use for any bivy.

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