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Unmanageable wetness this weekend
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Dave -
(FamilyGuy) - F

Locale: Up there
Unmanageable wetness this weekend on 10/04/2011 12:56:41 MDT Print View

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?

Rick Dreher
(halfturbo) - MLife

Locale: Northernish California
Re: Unmanageable wetness this weekend on 10/04/2011 13:10:18 MDT Print View

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.



Edited by halfturbo on 10/04/2011 13:11:07 MDT.

Ben Wortman
(bwortman) - M

Locale: Nebraska
Tent on 10/04/2011 13:12:20 MDT Print View

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.

Dave -
(FamilyGuy) - F

Locale: Up there
Re: Re: Unmanageable wetness this weekend on 10/04/2011 13:19:28 MDT Print View

@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!

Joe Clement
(skinewmexico) - MLife

Locale: Southwest
Unmanageable wetness this weekend on 10/04/2011 13:19:43 MDT Print View

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.

Dave -
(FamilyGuy) - F

Locale: Up there
Re: Tent on 10/04/2011 13:21:28 MDT Print View

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!

eric chan
(bearbreeder) - F
bivy on 10/04/2011 13:28:03 MDT Print View

which bivy?

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?

edit ...

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 hypothesis

Edited by bearbreeder on 10/04/2011 13:35:12 MDT.

Dave -
(FamilyGuy) - F

Locale: Up there
Re: bivy on 10/04/2011 13:41:58 MDT Print View

Eric -

-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.

Diplomatic Mike

Locale: Under a bush in Scotland
Perfect storm. on 10/04/2011 13:59:10 MDT Print View

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?

eric chan
(bearbreeder) - F
my WAG on 10/04/2011 14:00:40 MDT Print View

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 helps

Edited by bearbreeder on 10/04/2011 14:07:27 MDT.

Dave -
(FamilyGuy) - F

Locale: Up there
Re: Perfect storm. on 10/04/2011 14:07:10 MDT Print View

@Mike - I sure wish I had a tent this past weekend!

Justin Baker
(justin_baker) - M

Locale: Santa Rosa, CA
Re: Re: bivy on 10/04/2011 14:09:19 MDT Print View

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.

Mary D
(hikinggranny) - MLife
Re: Re: Re: bivy on 10/04/2011 14:46:49 MDT Print View

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!

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: bivy on 10/04/2011 16:55:32 MDT Print View

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.


Alex H
(abhitt) - MLife

Locale: southern appalachians or desert SW
Re: Re: bivy on 10/04/2011 17:15:54 MDT Print View

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?

Dave -
(FamilyGuy) - F

Locale: Up there
Re: Re: Re: bivy on 10/04/2011 17:38:42 MDT Print View

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.

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
Unmanageable wetness this weekend on 10/04/2011 18:06:04 MDT Print View

Roger, would have an eVent bivy performed any better in the same conditions/use?

eric chan
(bearbreeder) - F
Re: Unmanageable wetness this weekend on 10/04/2011 19:23:53 MDT Print View

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 ;)

USA Duane Hall
(hikerduane) - F

Locale: Extreme northern Sierra Nevada
Just like a ground cloth draped over u on 10/04/2011 20:31:02 MDT Print View

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.

Jeffs Eleven
(WoodenWizard) - F

Locale: Greater Mt Tabor
Re: Re: bivy on 10/04/2011 20:57:41 MDT Print View

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.