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usmc_2tothetop
Nov 3, 2004, 3:36 PM
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So I got a new bag (down, -20) and a new bivy (OR gor-tex) I tested it last night in my back yard. I assume it got down to 35 maybe. Kind of windy and cold rain. My bivy did a great job at keeping the water out BUT the condensation build up was significant enough that my bag got wet. Though my bag is water-resistant you know how down is when it's wet. What can I do to prevent this.
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cologman
Nov 3, 2004, 3:43 PM
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Synthetics
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kimgraves
Nov 3, 2004, 3:51 PM
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I find down is only good for fair weather - car camping. It’s just too hard to keep it dry and functional in real life situations. I’m slowly moving to all synthetics.
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couchwarrior
Nov 3, 2004, 3:52 PM
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That's a losing hand no matter what your bag fill. Too much ambient moisture in the air, not enough breathability in your setup (bag shell + Gore) and a bag warm enough to make you crank out plenty of vapor that had nowhere to go.
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usmc_2tothetop
Nov 3, 2004, 3:55 PM
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Maybe I'll get a slightly cooler (0-15) synthetic bag. I'm hoping in the colder months I won't have this problem. It was pretty damp last night.
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couchwarrior
Nov 3, 2004, 4:00 PM
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I believe down is the best insulator 80% of the time for what I do, and probably 90% of the time here in Colorado. There isn't much moisture content in our snow, the summer is fairly dry, etc. But when the air is moist and above freezing and you're in a bivy sack and warm bag, synthetics have an advantage. I have shivered in drizzle and mist in a down bag / bivy while my friend slumbered dry and toasty in a synthetic bag and no bivy.
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sarcat
Nov 3, 2004, 4:08 PM
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I've had the same problem. I've done several things to help.
1. Leave a crack somewhere and breath in and out of it. Don't freeze your lips.
2. Get a fleece liner for the bag. You'll get as much condensation but the liner will hold most of it protecting the dryness of the bag.
3. My bivy is a North Face bivy that has the two poles that create a "head tent". I've used one of those little candle lanterns hanging inside = 0 condensation (safety issues aside).
4. Put several of those had warmers in the bag. They don't absorb water but they do seem to make it feel like there is less condensation.
Edit: I have both a NF Blue Kazoo and a Cat's Meow. One down, one synthetic for different applications.
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getout247
Nov 3, 2004, 4:14 PM
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I would bet that if you were in a 20-30 degree bag, down or synthetic, you would have slept just as warm and had considerably less condensation. I have the same set up and find that when used with appropriate temp. rated bags, the OR Gortex accumulates very little condensation. The opposite is definately true if your bag is too heavy. If it was truely -20 degrees outside, any condensation would most likely be frozen anyway, keeping your bag dry. Plus, you probably would have saved a couple of pounds on the long approach from the back door to the lawn.
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usmc_2tothetop
Nov 3, 2004, 4:17 PM
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I guess OR bivys' don't breathe well.
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climb513a
Nov 3, 2004, 4:22 PM
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When the temperature inside your bivy is relatively warm and the outside temp is lower than dewpoint (The point at which air condenses) - the rapid changing of temp from inside bivy to outside temp (when the warm moist air hits the shell of your bivy) - - we have condensation. Like others, the central north west is very dry and the dewpoint is usually very very cold temps thus less condensation (necessarily).
I worked in SW Utah for more than a year as a wilderness guide using a bivy extenisvely during all 4 seasons. Even though we have a dry arid desert region - the moisture influx is variable and extreme in some parts of the year.
My solution to condensation is (to concur with previous posts) SYNTHETICS is the answer - and dont use a bivy unless its raining. Otherwise a worn out blue poly tarp works better becuase it breathes much better while shedding an ample amount of snow. Just throwing your softshell stuff or fleeces inside between bivy and bag works well when you have a sunny dry day ahead of you. Microweaves and Microfibers are great until you find out your condensating like crazy becuase you are sleeping in your bivy when its not raining.
On the contrary to my weather dynamics previous - when the moisture content is high - dewpoint is high - thus condensation at relatively warm temperatures.
Well - even if everyone has said basically what I have said - I needed to get my post count up :lol:
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usmc_2tothetop
Nov 3, 2004, 4:23 PM
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I think getout247 is right. I'll try my jo-schmo bag tonight in the bivy and see what happens.
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jamescuth
Nov 3, 2004, 4:27 PM
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i find that lining the bag with a fleece liner helps a lot, but really it wont go away unless u can leave the OR open a little bit to get some air circulation. of course, that might mean u get a little cold.....
synthetics are prob the way to go,
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usmc_2tothetop
Nov 3, 2004, 4:37 PM
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Actually I had the bivy open alittle which might have let moisture in cause it was so damp last night. I didn't know they made fleece liners. Where could you pick one up. Any outdoor store?
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sspssp
Nov 3, 2004, 4:50 PM
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In reply to: I guess OR bivys' don't breathe well.
Naw, this is a problem with all bivy's. Any fabric has a tradeoff between breathability and waterproofness. Since you want your bivy to be waterproof, breathabiity is going to be limited.
Keeping a small opening in the bivy sack that you can breathe out of will help. Another item, which I am surprised nobody has mentioned is you can get a vapor liner that you put inside the bag. It doesn't breath at all, which means you will get wet, but it will keep moisture from your body getting your bag wet. Definitely some tradeoffs, but something to consider.
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murf
Nov 3, 2004, 4:52 PM
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In reply to: Actually I had the bivy open alittle which might have let moisture in cause it was so damp last night. I didn't know they made fleece liners. Where could you pick one up. Any outdoor store?
You're going to try a fleece liner ( which adds warmth ) in a -20 bag? When the outside temp is 35? It could have been dry as a bone outsite and a -20 bag in +35 is gonna be a sweat fest, bivy or no bivy. I'm guessing you could pour yourself out of that bag.
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usmc_2tothetop
Nov 3, 2004, 4:59 PM
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Yea it was pretty toasty. I was just testing the bivy outside. Didn't get the storm I had hope for last night.
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thegreytradster
Nov 3, 2004, 7:32 PM
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Been using an OR bivy for several years now and have had condensation problems with only two situations.
Raining like hell and the bivy zipped up tightly traping extra condensate from resperation.
Took the winter bag when I should have had the summer one. Outside of the bag hits dew point. If it's cold enough you'll get frost on the outside of the bag, but you'll usually get just as much or more with no bivy sack. Just shake it off in the morning before it melts.
There's a trick to tucking the fabric under the lower (away from head) hoop that keeps the lid folded back exposing your face and shoulders. (they should add a velcro tab there). That both allows for some circulation and keeps the condensation from your breath from being traped and the net off your face if it's bug season.
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shakylegs
Nov 3, 2004, 7:42 PM
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Instead of fleece, if you don't want to add too much more warmth to the bag, try a silk liner. Or save a few bucks and go with a synthetic liner.
I'm sure you could find them at REI or EMS. Or, since they're non-dealer, you can even order them from MEC.ca.
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usmc_2tothetop
Nov 3, 2004, 8:29 PM
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I'm going to try my cooler bag tonight and see if that makes a difference. I'll also try to breathe out of the bag. I'll post the "results" on this thread tomorrow.
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chriss
Nov 3, 2004, 10:14 PM
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In reply to: 1. Leave a crack somewhere and breath in and out of.
This is the #1 rule of bivys and most tents. No waterproof/breathable fabric will breathe enough to keep you alive if there is no vent. You MUST have a vent.
If you zip a bivy over your head, even with a vent, you have to expect some condensation from your breath. If the condensation appeared localized in the lower part of the bag, it is probably from being to warm in your bag.
chris
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punk
Nov 3, 2004, 10:28 PM
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my opinions are here
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climb513a
Nov 3, 2004, 10:46 PM
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Yeah - breathing out helps by lowering the temp inside the tent/bivy and decreasing vapor content in the air inside -- thus lowering dewpoint. The key is to keep the tent cool inside and low vapor content -- thus driving dewpoint down in temp lower than current temp.
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scott_davidson
Nov 4, 2004, 12:02 AM
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I don't know if i agree about all bivy sacks having problems with this. I have used my bibler bivy with a down WM water repellant 5 deg. sleeping bag and never woken up damp. 2 different situations have for example:
1- wall climbing on a rock ledge after snowfall was melting so there were puddles and dripping on us all night, inside bivy sack and down stayed totally dry. 2- on snow, probably 15 degrees and clear weather but no other shelter besides bivy sack, no condensation build up either inside sack or in down.
scott
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gumbyinahumvee
Nov 4, 2004, 12:48 AM
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gore tex is a horrible material for shelters, this is why single wall tents are not made of them, and this is why gor tex bivvies suck nuts. Bibler and Integral designs are two companies that i know of that make single wall shelters with a material that is fuzzy on the inside. the fuzz helps to collect moisture so it doesnt drip . the fuzz help draw moisture out through the material. if you dont know what kind of material I am talking, please go feel the inside of a bibler tent or integral designs bivy before you comment.
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jimdavis
Nov 4, 2004, 1:08 AM
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I just really used my bivy this past weekend for the first time in the rain. It was an OR Standard Gore-Tex bivy and a synthetic 25 degree bag that's seen plenty of abuse.
I hung the little loop on the top of the bivy from a branch to keep it off my face, and I kept the bivy open about 8 inches.
I discovered a few things with this setup. Stripping down outside your bivy getting ready for bed sucks. You have to "worm" into a sleeping bag w/o getting it and yourself wet, and there is no weather protection for your shoes and pack.
So, what I'm considering now is using a really small (5' x 5') tarp in conjunction with my bivy. By setting the tarp up over my head, I can have the bivy completly open by my head, I can sit up and stay dry, and I can keep my pack and boots dry easilly. This will reduce condensation, and make things so much more comfortable.
It'll add a little weight, but if you make one out of Tyvek or something it could be really light and comfortable. The MSR Alpine Awning would work well if you had another person with you that had a bivy too.
I'm sure I'm not the first one who's thought of this, but I think it's a good idea.
Cheers,
Jim
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