Oct 4, 2011 at 11:56 am #1280165
This past weekend, while sleeping in a water resistant bivy under a pyramid tarp, I got wet. VERY wet. It was raining with temps around 2C and 100% humidity for over 8 hours. I used a thin polycro groundsheet that covered most of the pyramid but the moisture in the air was significant. My bivy was completely soaked, which collapsed the down in my quilt, which became almost useless 1/2 way through the evening. I also slept in insulated synthetic clothing (top and bottom) which quite frankly, saved me.
What did I do wrong? The ground was obviously soaked and contributed to the moisture issues, but should I have used a waterproof bivy? Should I have just used a tent with a floor?Oct 4, 2011 at 12:10 pm #1786589
@halfturboLocale: Northernish California
My sympathies. Rainy and just above freezing are pretty much my textbook definition of miserable, and reminiscent of the PNW. What kind of bivy is it? Was dew soaking through or were you getting hit by rain spatter or dripping condensation? Does the pyramid have top vents and how close to the ground was your bottom edge?
With that shelter system I'd have wanted a WPB bivy and synthetic bag. Otherwise, I'd have preferred either a large open tarp to maximize both protection and ventilation or a more traditional tent.
RickOct 4, 2011 at 12:12 pm #1786592
Perhaps a tent with a floor would have kept the condensation moisture from the ground out of the shelter. Without a bivy, if there were not drips falling from the tarp, you might have been better off since it is possible with the high humidity, that the bivy trapped too much of the moisture inside insted of letting it escape. I heard somewhere, that once the outside of a bivy or jacket gets wet, it essentially forms a barrier/layer that moisture cannot pass though and therefore holds all the vapor in.
I once spent the night in a tipi in similar conditions to you (all night rain, high humidity, out in a meadow with long grass at 11,500'). In the morning, the inside of the tipi was super wet (did not drip though), but my down bag was just slightly damp on the outside.Oct 4, 2011 at 12:19 pm #1786599
@rick – thanks. Yes, the pyramid has an upper vent and the bivy was an MLD SL with momentum top. There was decent coverage so it wasn't rain splatter and although there was condensation on the inside of the mid, the bivy had a thin layer of wetness from top to bottom.
I thought I may have encountered the perfect storm so to speak. Looks like you have confirmed it. It sucked!Oct 4, 2011 at 12:19 pm #1786600
I'd guess the bivy trapped moisture, but it's only a guess, since I've only seen 1" of rain in the last 12 months.Oct 4, 2011 at 12:21 pm #1786601
Thanks Ben – I was at similar altitude. As you say, the bivy may have been more of an issue than first expected. While used to keep moisture off, it may have kept it there. I wish I had more time to experiment but it was time to get off the mountain!Oct 4, 2011 at 12:28 pm #1786605
and was the moisture mostly on the inside of the bivy, the outside of the bivy or the inside of the tent itself …
did you wear the synth cloths inside the down bag, or layer em on the outside?
also was the moisture on the outside shell of the bag or inside the outer shell, which bag, and how much down collapse did you notice
i suspect i have an inkling of the problem … but with any troubleshooting one needs to know the info before making a hypothesisOct 4, 2011 at 12:41 pm #1786613
-the bivy was an MLD SL with Momentum top.
-Moisture was on the outside shell first and then appeared to wet through to the down quilt.
-Substantial loss of loft. Maybe from 3" to 1". Quilt was a Golite 3 Season quilt with WP ends but 20D (I believe) nylon in the main part.
-I was wearing my synthetics under the quilt.Oct 4, 2011 at 12:59 pm #1786623
@mikefaedundeeLocale: Under a bush in Scotland
By an amazing coincidence, 3 of us had exactly the same experience here in Scotland this weekend. We even used the words 'perfect storm'!
I was using a Stephensons 2R, Ed Hyatt (member on here) was using a Scarp 1, and Mick had an Akto.
We were stopped by a river in spate, and forced to pitch on saturated ground, with all night rain. The difference was that our sleeping bags/quilts stayed dry, but everything else was soaked. It was the worst condensation i've ever seen.
As we were in enclosed tents, the condensation was far enough away from our bags/quilts to stay dry. I can only think that it was because your bivvy was touching the quilt that the condensation transferred to the quilt?Oct 4, 2011 at 1:00 pm #1786625
david … heres my WAG
1. condensation from the ground … i would rule it out as a major factor unless there was a lot of condensation on the inside of the tarp which dripped onto the bivy itself … this does not seem to be the case … if it was, then thats an issue … note that higher humidity inside the tarp can contribute indirectly and this could add to it
2. rain leakage … again from what i understand it wasnt a major issue … you should have seem splitter splatter onto the bivy if it was
3. condensation from body vapor … from yr description this appears to be the main cause, no doubt the high humidity helped as well … the bivy likely trapped body vapor and contributed as the dew point was very possibly inside the bivy, or even inside the quilt at times … also using synth inside a down bag is not advisable IMO, more on that later … was the bivy all zipped up? … you may want to use an unzipped or mesh bivy next time, or even forgo the bivy if dripping condensation are not issues
now to the synth inside, i generally use synth as the last layer because
a. body vapor will move outwards, and the dew point is usually somewhere in the outer layers … if using down bag, ill put the synth jacket drapped over the outside, that way the dew point is more likely to be in the synth jacket … if using a synth bag and down sweater, ill wear the down inside the bag for the same reason
b. outside condensation such as drips, splashes, or just condensation from yr bivy will end up on the synth rather than the down shell … protecting yr down bag better
c. generally you want the "warmest" layer next to you, same concept as you dont want air pockets in yr sleeping bag as youll need to heat them up and they are less insulating than yr bag … synth is generally less insulating than down, so you want the down close to yr body
i would recommend layering the synth over the down, ventilating the tarp as well as possible, unzipping or even not using a bivy
with a fully protected pyramid tarp you could probably get away with just putting yr synth jacket and a layer over the bag … if you do use a bivy, keep yr synth jacket between yr quilt and the bivy for the reasons mentioned above … and take off all wet clothes before getting into a down bag, just layer them on top of yr synth jacket of needed
you can also use a hawt nalgene for pushing out the moisture out of the system … also try renewing the DWR on yr quilt with spray on, might help in the future …
or use a cats meow like i do ;)
thats my opinion anyways without seeing the actual conditions and setup
hope that helpsOct 4, 2011 at 1:07 pm #1786627Oct 4, 2011 at 1:09 pm #1786630
@justin_bakerLocale: Santa Rosa, CA
A synthetic bag or quilt might be a good investment if you are expecting such conditions. In some places where just leaving your bag or clothing exposed to the air will get it soaked, I have even carried a wool blanket. Heavy, I know but it will keep you alive. This insulation wont collapse the the fibers naturally retain heat even when wet.
Either way, this shows the importance of being able to make fire in any weather for your own survival. I have rearanged my tarp in the middle of the nigh, flipped on my headlamp, and got one going in a storm. It is well worth it when you are wet and cold.
Hopefully you figure out your problem. It sounds likely your bivvy was the biggest issue.Oct 4, 2011 at 1:46 pm #1786656
@hikinggrannyLocale: Gateway to Columbia River Gorge
It really sounds like body moisture going through your bag, condensing on the inside of the bivy and, because of the direct contact, being rubbed back into the down. If the clothing you wore to bed was damp, that would have made things worse. It might have been that at the start you were too warm and did some sweating, which would of course exacerbate the problem.
Even though it was a little above freezing, a vapor barrier might have been a good idea to keep your body moisture out of the bag. I've done this on cold, wet nights and it does help. Of course you wear your insulating clothing outside the vapor barrier to keep it dry, too!
Without a bivy, and while above freezing, the moisture would have condensed on the inside of your pyramid, which might have been a preferred alternative. You can wipe off the excess and if the DWR on your sleeping bag is good, a few sprinkles won't penetrate. The few times I've tried bivies, I've had very poor luck with them–either condensation inside or compression of the down on my sleeping bag as a result of the twisting from my tossing and turning. YMMV, of course!Oct 4, 2011 at 3:55 pm #1786730
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
Mary D is about right.
The vapour from your warm sweating body condensed on the inside of your bivy *because* the outside of the bivy fabric was so cold and the external humidity was so high. That water then wet out your SB.
You were above freezing, so I would not recommend a VB liner. It might work – maybe.
About the best you can do in these conditions is to use a large-enough good double skin tent and to sleep cool with NO wet clothing inside the bag. The inside of the fly will still get wet. Hopefully the inner tent will not get too wet from the drips of water, but will let the water vapour through to the fly.
UL bivies etc in these conditions simply do not work. Trying to dry clothing inside your SB does not work either. Understand that, accept that, and deal accordingly.
CheersOct 4, 2011 at 4:15 pm #1786746
@abhittLocale: southern appalachians or desert SW
Eric's comment #3 is correct as is Mary D's. I have had similar results with my MLD SL as I commented on in my bivy condensation piece.
David I thought you were an eVENT bivy owner?Oct 4, 2011 at 4:38 pm #1786761
Thanks Eric, Mary, and Roger – makes perfect sense. And is quite upsetting as well. I should have known better.
Alex – I do – an ID eVent overbag but I wasn't expecting it to be cold so took the more breathable bivy. I haven't had such issues with the ID in the snow so was surprised at what I experienced with the SL.Oct 4, 2011 at 5:06 pm #1786770
@thomdarrahLocale: Southern Oregon
Roger, would have an eVent bivy performed any better in the same conditions/use?Oct 4, 2011 at 6:23 pm #1786794
im no roger … but no IMO
the problem is condensation from the inside of the bag, not the outside … a single DWR bivy is likely as breathable as an event bag or more so …
the problem IMO is two fold … using synth under down (there are threads where people have come out with damp down using a down quilt/bag over a synth bag) and the lack of airflow inside the bivy (again there are threads about this), possibly damp clothes as well … the dew point IMO was effectively inside the bivy or the quilt
while its great to bring a double wall tent and a synth bag for such conditions … IMO on should know the steps to minimize the problem without relying on such, as you could be on a trip already and the weather changes for the worse …
one smart think david did was not to depend on down exclusively IMO … its nice to hedge yr bets sometimes
or just use a cats meow ;)Oct 4, 2011 at 7:31 pm #1786820
USA Duane HallParticipant
@hikerduaneLocale: Extreme northern Sierra Nevada
Sounds like what I experienced slightly on a Pacific coast trip to the Mendocino area here in CA. Had never camped on the coast, we were a mile or so inland in a CG. A warm night so I just draped half my ground cloth over me to keep dew/fog off. The next morning, the gc was dry on the outside, but between my down bag and the gc it was wet from condensation. At least my bag was not soaked, just the material was wet.
DuaneOct 4, 2011 at 7:57 pm #1786831
What Mary and Roger said sounds right to me about the bivy rubbing it back into the bag. That happened to Darin Banner on Crater Lake a couple years ago.
IMO Eric has the solution with synth on the outside. Dew point management. I'd be hard trying to keep clothes on your bag but the theory is right. At 100% humidity its gonna condense somewhere- the further from your body/ and SB the better.
The danger is not having enough heat to push the moisture out. Darin did situps at night but with only a ridgerest on snow he evidently couldn't create enough heat to get the moisture through the bivy. Not for long- anyway.Oct 4, 2011 at 8:11 pm #1786835
So….drop the bivy, use down clothing with a synthetic sleeping bag. Use a tent with floor if possible, preferably double walled.Oct 4, 2011 at 8:13 pm #1786837
@davidadairLocale: West Dakota
Sometimes I just fire up the stove with an empty Titanium pot on it. The radiant heat drys things out pretty fast-at least for a while. (make sure you leave the lid off and don't turn it up much) Sometimes a candle helps-sometimes not. Sometimes I wish I had my little primus lantern. Need to remember to stuff any wet clothes in a plastic bag so they don't add to the problem. Usually just suffer through it like everybody else. Type 2 fun eh?Oct 4, 2011 at 8:15 pm #1786840
You gotta admit, this is pretty fascinating, from a technical point of view.Oct 4, 2011 at 8:26 pm #1786844
Joe – I agree. Things got so bad for me, I had to trek out early – less a planned day. I could not spend another night out.Oct 4, 2011 at 8:27 pm #1786847
jeff … hot nalgene … which is why i love having one despite the weight , and love the jetboil for the fuel efficiency should i need to boil more water than expected … also cords can help keep yr clothing in place … or at worse some medical tape (which should be in yr 1st aid kit or something similar)
joe … says the guy who lives in new mexico …
david … im not saying synth bags are the only option … but if you do use down id suggest learning every trick in the book to dry out yr bag and prevent moisture … like anything else sometimes the weight savings require more skill and fuss .. also consider that 900 fill down is effectively 700 fill at 50% humididity, never mind 90%+ … so youll likely need a heavier down bag to make up for the loft loss
heres a good link for the oh shiet scenario … also there are the old excellent BPL articles on condensation
and the excellent pictures at pages 6,7 here for clothing … same applies to bags
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