sixstringsteve
Well-Known Member
- Location
- UT
Gotcha. I'm going to have to try that next trip out.
Bivy Sacks. Feedback?
- Thread starter sixstringsteve
- Start date
kd7kmp
Registered User
- Location
- Springville, UT
Condensation in confined quarters--like a bivy--during winter camping conditions will always be an issue...especially when it's very cold. The limited volume in which you are sleeping concentrates exhaled water vapor. Because of the low temperature there is very little time for water vapor to move out before it condenses (freezes) to the inside of the bivy even if the foot vent and head vent are open. It's just the nature of the beast. You would need fairly good air flow (usually provided by wind) to remove the water vapor, but bivy sacks typically restrict air flow due to the confined quarters. If you spend time researching lightweight camping/backpacking gear you will find that many people prefer a lightweight tarp to a bivy for the simple reason that a tarp allows much more airflow than any bivy while still providing the necessary shelter from the elements. Some will combine a lightweight tarp with a very breathable bivy--one with a breathable top and waterproof bottom--to keep the warmth advantage a bivy provides while still combating condensation.
Kevin
Kevin
sixstringsteve
Well-Known Member
- Location
- UT
interesting. Thanks Kevin.
In order for a waterproof down bag to be effective they need to have a vapor barrier lining. Otherwise imagine the frost that was in your bivy on the inside of your sleeping bag. Not good.
Yes with vapor barriers your skin collects all the water instead of the bivy or sleeping bag, they are not comfortable for everyone, but they are effective. You do not cool down from the water on your skin. The water doesn't move through evaporation or convection so you stay warm and the water stays out of your bag and off of you bivy sac. You still have to breathe so there will be condensation from that no matter what you do. If you are relying on you tent system for any amount of warmth you will get condensation. Even super high dollar double wall tents get it. It just condenses on the outer wall so you don't notice until it is time to pack up. A heater, eVent, goretex, synthetic, down, whatever will not stop ice crystals in cold weather. A long as there is moist air on the inside of the system it will condense on the cold shell of the system. It will condense at every temperature differential. Body to sleeping bag shell and the sleeping bag air to tent/bivy wall. You can't stop it and have yourself covered up. As long as you remove the ice crystals before they melt it shouldn't be to big of an issue with wetting out your bag.
Also if you are getting a ridiculous amount of condensation then you are sleeping too warm.
This is why I bought the annex. I put the heater outside on the floor and all the heat comes up into the tent. Don't have to worry about it melting anything. Never ran it all night but for several hours for sure.
JL Rockies
Binders Fulla Expo
- Location
- Draper
Dontcha think my idea would work? I think it would.
sixstringsteve
Well-Known Member
- Location
- UT
Yes, with one or two exceptions:
- May cause mechanical irritation to the eyes and skin.
- May cause irritation of the digestive tract if ingested.
- Dust is irritating to the respiratory tract if inhaled.
- Prolonged exposure to inhaled dust may cause delayed lung injury/fibrosis (silicosis).
Though it might provide the same result as Cody's suggestion to stop breathing.
JL Rockies
Binders Fulla Expo
- Location
- Draper
Don't eat it. I bought a ready-made dessicate pack in the laundry section at WalMart when my Jeep got swamped and ended up with 2" of water inside. In the FL heat, the windows would fog up all the time days after the stanking water was removed. The thing I bought were like pellets ina small bucket. After a week, the bucket was full of water.
STAG
On my grind
- Location
- Pleasant Grove
Fwiw I run my Mr Buddy all night with a vent cracked open. I do have a carbon monoxide detector and it never alarms.
I wouldn't worry about carbon monoxide with one of those but they do eat up the oxygen and you could suffocate, your alarm wouldn't detect this.
- Location
- Grand Junction, CO
The Mr Heater Buddy has a low oxygen sensor which will shut it off when tripped.
- Location
- Grand Junction, CO
I read this and had dirty thoughts
I had the same thought, but wasn't going to take there.
I have a Mr. Buddy heater that I've used when I was fishing on the lake. Our season was from November 1 through the end of February, so some of the coldest months. I was generally driving a speed boat which I also slept in the cabin of, but had to be able to hear the radio at all times. As a result, I'd sleep with the door wide open and the Buddy Heater blasting away. Kept things nice and warm even in the coldest weather.
sixstringsteve
Well-Known Member
- Location
- UT
Dragging this up from the dead. I'd love a bivy for quick overnighters where i don't want to pitch a tent. If you were go get a bivy for winter, what would you get? My army bivies are great for when the temps are above 20*. Below that they get condensation on the inside. I'm thinking about an all-eVent bivy. Thoughts?
rondo
rondo
- Location
- Boise Idaho
I don't know a thing about civilian stuff but have spent more time the than I care to share in my military sleep system. nice thing about it is it drys out quickly when needed, you can take all of it or parts of it, and it packs up tight. The older system seems a bit lighter than the new stuff.some Soldiers I've seen will put their sleep pad inside the waterproof cover, with 1 or 2 bags in it as well depending on the weather.
one of my good friends is an outdoorsman, runs marathons, hikes, jumps off of cliffs (I forget the name of that sport but I think its called dumbf##$%ery) etc and he never uses the army sleep system haha
I have frozen my rear off in the thing however in the new mexico desert so i'm not too impressed. not that cold out I think, its just I could not get warm no matter what. of course we had drank a lot of that Mescalero apache fighting whiskey the night before
An event bivy will be better for condensation than your goretex bivy, but you will still get condensation. It will probably just be frost which is much more manageable in the real world.
I use a bivy with an m50 top which is super breathable, but not waterproof. It is a Borah gear product and they do great work. http://www.borahgear.com/sidebivy.html
If I were going to do an event bivy it would be this one http://www.borahgear.com/eventbivy.html They are a great company with great cusomer service. They even built my bivy custom sized for me to fit my thick pad and loft bag. (and lofty belly). Borah is affordable and good quality. (steve you know how picky I am)
Cruiser
look what i can do!!
I have Used a Bivy sack many times in AK... Great for death march hunting, the only problems are the ground is not always that comfortable, and condensation in the bag can be a problem.. We built rock walls shoulder width apart to put our packs on so that our heads could stay dry underneath.
sixstringsteve
Well-Known Member
- Location
- UT
Darn. I don't care if it's waterproof so much as it allows the frost to pass through my bag to the bivy, so the frost collects on the outside of the bivy. I'm not worried about getting rain or snowed on, I can carry a tarp for that.
I may have to check this out next time I'm at your house. The price is definitely right on these! Do they have zippers to get in, or do you have to climb in through the hole where the head is?
Basically, I want a sleeping solution that allows me to be able to sleep under the stars in the snow or cold and not have to worry about my bag being covered in ice or water droplets the next day. I imagine I need the bottom of the bivy to be waterproof enough that snow or rain doesn't soak through and get me wet from underneath. I don't need the top to be waterproof, I can use a tarp above me for rain/snow conditions (not too frequent here in Utah).
It's probably obvious that I still don't understand dew points or how at certain temperatures you can get condensation/ice in the middle of your bag, before it even reaches the outer shell. Davy (or anyone else) can you explain that to me?