Sep 9, 2010 at 5:29 pm #1263138
When the mercury drops, I still like to hike and camp. I really like settling down all cozy, dry, and warm in my bag each night.
But the mornings are different. The vast majority of mornings I wake up with noticeable condensation in my down bag. It's not uncommon for me to sit up in my bag, and where the crease is near my waist, visible water is forced out. Well, enough to make the shell fabric damp. I actually thought I spilled some water on my bag one morning.
It's also bad near my feet. I can just feel the moisture if I squeeze the footbox.
I can't find a pattern to when this happens either. I try to vent my bag as much as possible, but when its really cold, I have to zip up.
I'm using a Marmot Pinnacle 15F bag.
I'm normally not an overly-sweaty person, but I do tend to sleep warm.
Winter season is coming and I'd like to try and remedy this. Must I get a VBL system? Is this normal?Sep 9, 2010 at 5:40 pm #1644339
John NausiedaBPL Member
What kind of tent/tarp are you sleeping in/vents? near water or vapor?temps?Sep 9, 2010 at 5:41 pm #1644341
@mikeclellandLocale: The Tetons (via Idaho)
This is absolutly NORMAL.
You will ALWAYS have a little condensation on your sleeping bag. More in a tent than in an igloo.
As soo n as you get up in the morning – set your sleeping bag out in the sun – or breeze – or even light snow. Hang it in a tree, or on your skis.
Give your sleeping bag 20 minutes, it helps a LOT.
Some folks like VB liners, but I find they are a real-deal hassle. THe best solution I have found is using a super light synthetic sleeping quilt INSIDE or OUTSIDE your sleeping bag. The lightweight BPL cocoon is PERFECT.Sep 9, 2010 at 6:19 pm #1644359
On 99% of mornings I have zero condensation except for very mild condensation only on the footbox.
Bag- RAB quantum top bag (hoodless)
Sleeping bag cover- Equinox
Shelter- Golite Hut 1Sep 9, 2010 at 6:21 pm #1644360
John, do you attribute your condensation-free mornings to your bag cover?
Mike, I'm guessing you're suggestion to use an over-bag to help push the dew point out of the sleeping bag?
Oh, forgot to add…. I either sleep in a Double Rainbow, or under a Trailstar. I try to pitch them open/high as much as weather and wind permit.Sep 9, 2010 at 6:24 pm #1644361
Condensation free (except footbox) due to bag cover and hoodless bag so there is no way I am accidentally breathing even slightly into the bag. The pertex quantum fabric of bag and good breathability of the equinox cover are also contributory. I am not an overly warm sleeper.
That was for three season (missed that part initially).
In winter I have used a neatsheet as sleeping bag cover (because equinox is not for winter) and get no condensation even on footbox, but maybe a little frost around the bag opening. I have only about 10 bag nights of winter experience though.Sep 9, 2010 at 7:40 pm #1644378
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
Inside the bag: 38 C and 90% RH
Outside the bag: -10 C and negligible humidity
Guess where the dew point is going to be? Inside the bag of course.
It does help if you sleep cool instead. It won't kill you, but it will cut down the amount of water vapour you give off. That may help a LOT.
VBL works, but is a hassle. Try sleeping cool first, and do air your bag in the sun.
CheersSep 9, 2010 at 7:51 pm #1644383
I wonder how skurka makes VBL work so good, does anyone know a place where he discusses-perhaps a thread-his VBL solutions?Sep 9, 2010 at 8:01 pm #1644384Sep 9, 2010 at 10:42 pm #1644405
. .BPL Member
@biointegraLocale: Puget Sound
Can you elaborate on the reasoning behind a synthetic quilt INSIDE a down bag? I can understand it outside, because of migrating the dew point to the outside of the down, but how would this function well in reverse? I have a BPL Cocoon quilt, but it is too narrow in the foot-box to fit well outside of a bag, so I am keenly interested in what you have to say.Sep 10, 2010 at 6:37 am #1644451
Jim MacDiarmidBPL Member
It does help if you sleep cool instead
By sleeping cool, this means not using a bag overly warm for conditions( a -10*F bag in 10*F temperatures), thereby preventing excessive sweating?
As I also tend to 'sleep warm', this would seem to be a point in favor of a quilt, which would allow some of this excesive heat to escape rather than be trapped in a sealed bag.
Can you elaborate on the reasoning behind a synthetic quilt INSIDE a down bag?
I'm interested in this as well. Except instead of using the cocoon quilt, I'd be using the Cocoon pants and parka. I really like the idea of wearing synthetic insulation to bed, as it makes getting up for those middle of the night bathroom trips a lot easier.Sep 10, 2010 at 6:56 am #1644459
Steven EvansBPL Member
A VBL will help for sure, as will the other suggestions.
I'm a VB user, and looking from the opposite point of view from Mike and Roger (who are no doubt much more experienced winter campers than me, so this is just my opinion), I find it a hassle to get up in the morning and dry my stuff out before hiking. Mornings are stinkin' cold up here in the winter, I want to spend as little time in camp hanging around and more time moving to warm up. I use a VB system and this lets me do that. No hot drinks or cooked meals in the morning either – I just get moving.Sep 10, 2010 at 8:13 am #1644480
Dale WambaughBPL Member
@dwambaughLocale: Pacific Northwest
Camping on the West slopes of the Cascades in any season can find you waking to 80% plus humidity and 45F-50F temps. Think cold steaming jungle :) Your perspiration and respired moisture simple has nowhere to go, let alone ground moisture captured under your shelter and condensed. Campsites can vary a lot too. I've had dew-soaked brush on the trail get me as wet as any downpour. That's why I leave down for my lightest bag for SUL "height of summer" overnight trips in my area. Getting the bag out in the sun/wind before packing and on rest stops is about all you can do once it is wet. There is virtually no direct sun on the west side of the Cascades in Winter and lots of drizzling precip, so the drying option is really a hallucination. Body heat will help with mildly damp insulation. Many a good bit of equipment has been fried around here while trying to dry near a campfire.
Answers? Ventilation, campsite choices, breathable but water resistant bag fabrics.Sep 10, 2010 at 11:23 am #1644538
eric chanBPL Member
my questions is how to deal with down in periods of extended rain like Dale mentioned above
we get rain and humidity and possibly no sun for days on end hereSep 10, 2010 at 11:33 am #1644543
@owareLocale: Steptoe Butte
In continuous damp conditions, a liter bottle of boiling water in the sleeping bag will drive out a lot of moisture.
VBL's are very helpful.
Synthetic overbags are luxurious.
A waterproof and breathable bivysack also helps move the
dewpoint outwards and keeps stuff dry (including the
pads) from external moisture.
In sub zero Cascade conditions, I may use all 4 things
together.Sep 10, 2010 at 2:49 pm #1644600
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
> By sleeping cool, this means not using a bag overly warm for conditions( a -10*F
> bag in 10*F temperatures), thereby preventing excessive sweating?
Exactly. If you are hot you will sweat. But there seems to be a temperature range where you can sleep comfortably while not sweating very much at all. After all, what is 'sweating' but a means for your body to cool off when it is too hot?
> Can you elaborate on the reasoning behind a synthetic quilt INSIDE a down bag?
Sorry, but I would NOT do this. I would put the down bag inside and the synthetic outside, in the hope that it is the synthetic bag which cops the dew point. That keeps the down bag dry – always a Good Thing!
The one place where what I am suggesting is not effective is when the synthetic bag is so heavy it squashes the down bag. Well, just don't take cheap heavy synthetic bags into extreme conditions.
CheersSep 11, 2010 at 8:56 pm #1644862
@owareLocale: Steptoe Butte
What do you think about the view that down reaches a better
insulation efficiency when compressed to a certain point?Sep 12, 2010 at 12:05 am #1644881
Here's a long shot, and I might just be grasping at straws…
But how does your body react when your top insulation (sleeping bag) is warm enough, but your bottom insulation (sleeping pad) is barely adequate? Does your body try to produce more heat to compensate for the coolness on your back resulting in excess heat on top?
I'm just wondering this because on the winter nights where I experience this condensation, I don't feel "hot." I usually go to bed warm, and sometimes even a little to cool for my taste, but never hot. And the few times I've tried to vent my bag, I just end up feeling cold.Sep 23, 2010 at 9:44 am #1648204
Travis, yup. I've noticed that inadequate insulation underneath begets more sweat; although I might not feel particularly warm (or even a bit cool), if I think about it I can detect sweat up top. Confused me until I figured out it was because I didn't have enough insulation underneath. Better insulation underneath fixes much of the problem for me. I do also use VBL in colder weather.Sep 23, 2010 at 10:58 am #1648227
I used to use a BA Insulated Air Core, but have since switched to a Kooka DAM. I haven't tested the DAM in anything below the upper 20s yet, but I'm hoping it will make a difference this winter. Man, it'd be great if that solved this issue!Sep 23, 2010 at 11:09 am #1648230
@mikefaedundeeLocale: Under a bush in Scotland
I'm happy to use a torso pad in warm temps, but switch to a full length pad when the temps drop. I used to get dampness at the footbox using a torso pad, and blamed it on condensation from the cold ground. It doesn't happen with a decent pad under the footbox.Sep 23, 2010 at 11:40 am #1648238
Hmmm, does anyone else have scientific proof or personal accounts of inadequate insulation below the body having an effect on condensation levels?Sep 24, 2010 at 8:56 am #1648499
@davecLocale: The West Slope
Travis, I don't have hard data on that, but it makes sense from an intuitive level.
I don't think there's a real solution for this. Oftentimes I pull my bag out and dry it during a mid-day break, ideally in a windy spot.
Sometimes (like during Le Parcour race last fall) you don't get a break in the rain/snow, and just have to deal with a bit of dampness in the bag. Having a bit of leeway in your total insulation setup is rather nice here.Sep 24, 2010 at 9:50 am #1648513
Nick GatelBPL Member
@ngatelLocale: Southern California
I can avoid the condensation with a VB liner. But as mentioned, they are somewhat of a hassle, and you have to almost sleep nude and you will feel clammy.
From what I have read, the body is going to produce about a pint of vapor overnight, and it has to go somewhere… seems it likes to travel to the foot box.
Also from what I have read, the vapor will move up through a quality bag, and up to the top. I have a REI minimalist bivy, and the moisture stay inside of it. My MLD Soul Bivy in Momentum top does much, much better. Also my Nanatak Arc Specialist breaths much better than my WM Ultralight. All of this is variable depending on conditions.
Regarding ground insulation. It seems to me, that if you are sleeping on the cold side, the body will react and might produce more vapor (but much less than if you are sweating).
So here is what I will be experimenting with this winter.
Insulation pad: Big Agnes Insulated Air Core mummy 72". In the past I have used full length foam pads with a BPL Torsolite or similar.
Quilt: Tim Marshall cuben with 2" of insulation. Should be good to 25F. If it gets colder I can add down layers, but that might be problematic, as the cuben will act like a VB liner. I have a BPL UL quilt (the lightest model) and I plan to play around with it in conjunction with the cuben quilt, but there is the chance that sizes might not match up, which could compress the down.
Bottom line is that I can avoid condensation with a VB liner, but would like something different that does not feel clammy.Sep 24, 2010 at 10:09 am #1648516
Nick, I feel the same way about VBLs. I experimented with some large trash bags that I had taped together just so I could get an idea of what it was like. While I could "deal" with the clamminess, I'm hoping to find a system that doesn't require VBLs.
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