Bivies…I want to love them…but…

[W I S N E R !]

. .. .. . …. ..

[W I S N E R !]

…I think I’m done.

Just returned from a Joshua Tree trip in which two of us had massive bivy failures.  No fault of the manufacturers (one MLD, one TiGoat), but troubles that can only be chalked off to switching conditions, inherent bivy limitations, and perhaps user error.

The night started off fine but ended with the worst condensation I’ve EVER experienced come ~2AM, to the point that it appeared someone dumped a bucket of water over my sleeping bag.  A damn-near supernatural amount of water if you ask me.  Which was of course followed by complete loss of bag loft….which was then followed by anything wet glazing over with ice.  Needless to say…it was a long, very cold night.

In retrospect, we were camped in a vegetated depression, but a steady breeze was blowing when we got in our bags, a breeze that had me assuming there would be enough air flow to keep dry.  Unfortunately, that breeze stopped in the night and temperatures started to plummet.  I wouldn’t have used the bivy at all were it not for that initial breeze.  By the time the damage was done and I woke up cold to find out how bad things had gotten, it was too late.

Our other partner in a Duplex stayed totally dry in his bag, though the shelter interior was soaked.

Ive been saved a few times by bivy camping and truly want to love it.  When solo hunting it allows me to tuck in on weird ridges, when desert camping it’s saved me in windstorms when shelters were having trouble.  I’ve used the bivy with success, surprisingly, on some surf trips in which we slept on the deck of a boat while anchored.

But is it pure luck?  After dozens upon dozens of nights in one, I’m beginning to feel like I can’t even pinpoint when a bivy will/will not work.  My experiences seem to run almost counter to what one would expect from conditions.

This trip had me seriously wondering what I have to gain by not just sleeping in my Solomid and skipping the potential condensation issues altogether.

 

[Adam White]

Was this under a clear sky?

I love a bivy, but I fear clear skies. I have no advice for the bivy sleeper on clear, cold, still nights.

[Jerry Adams]

yeah, clear sky bad because the fabric cools from radiative heat loss, then any water vapor will condense on it

did you breath into the bivy?  or was your head outside and breath blown away rather than condensing inside

[W I S N E R !]

Yeah, pretty clear sky.  But I’ve never noticed this being an issue in the past…a function of a particular temp/humidity combo?

Not breathing into it either.

[Alex H]

Sounds like you were right in the bad zone as far as temps and dew points.  I am increasingly looking at bivies with a strip of insect netting down the top but with breathable fabric sides part way up.

[Brad P]

Are these all weather bivies capable of being used without a tarp even in rain?  Would a bivy with more mesh used with a tarp alleviate the problem?

[Mike M]

these were lightweight bivies- waterproof bottom, water resistant/breathable tops

I’m leaning more towards poor site selection and possibly a “perfect storm” of environmental conditions

I pulled the bivy off of my bag (except the foot area) sometime around mid night; but my bag was further soaked as the night went on, thus thinking a heavy dew the major culprit

I’ve used that bivy on numerous occasions and while I’ve occasionally experienced some condensation, nowhere near what I experienced that night

night two, I took no chances and went higher and drier- no moisture/condensation issues whatsoever, just bitter cold with a too light quilt :)

night one

night 2

 

 

[W I S N E R !]

Nice ridge camp!

I was dry on night two, even sleeping down below.  That the breeze stayed up all night probably helped.

I guess the whole situation has me questioning why I should bother carrying a piece of shelter/sleep gear that has so much potential to cause trouble if conditions aren’t right.  As opposed to gear that I know will work in any conditions.  Perhaps better filed in a “Philosophy/Technique” thread.

[Jerry Adams]

I occasionally have severe condensation on inside of tarp.  Near 100% humidity.  Clear sky.  Tarp cools maybe 10 degree F from radiative cooling.  Severe condensation impossible to prevent.

I have had fabric suspended in the air, so there’s ventilation as good as possible.  There’s still severe condensation on the under side.  Maybe ventilation is actually bad because there’s a flow of near 100% humidity air.

If the wind picks up, a lof of the condensation will be knocked off the inside of tarp onto the outside of my sleeping bag – so it’s good to have a good DWR coating.  Or if it’s rainy and windy sometimes water will get blown onto outside of sleeping bag.

My bivy is M50 which has a good DWR but not real good breathability.  It’s tight around my shoulders so my breath and outside humid air is excluded.  I’ve never had any condensation on the inside.  The fabric is breathable enough that any insinsible perspiration from my body passes through the fabric.  I’ve been out many nights cowboy camping when it’s cold, 100% humidity, clear.  I’ve had a lot of condensation on the outside of the bivy.

This is inconsistent with reports of condensation on the inside of bivy which is confusing to me : )

I’ve tried bivy in the rain but that doesn’t work.  Either my face is open to the rain which isn’t good, or I have to breath inside the bivy which is a lot of water vapor and then everything gets wet.  I’ve tried mini tents over just my face.  There’s a good recent article (tivy).  But if it’s raining it’s difficult to get into sleeping bag, and then I’m stuck there.  I like to sit up, fiddle with stuff, run my stove,…  Pyramid tent is good.

[Nick Gatel]

It’s a common problem in the desert when temps get near freezing. Not unusual for me to get condensation on the top of my sleeping bag or quilt when cowboy camping without a bivy. I gave up on them about 10 years ago. IMO, they’re a bandaid for a poor shelter (small tarp) or trying to compensate for a bag/quilt that is not appropriate for the temperatures — and the disadvantages far outweigh the advantages. As a stand alone shelter I see no advantages at all — my Cuben shelters and tarps are lighter and more functional.

Four years ago I wrote that

For the backpacker who wants to supplement his or her shelter with a bivy, I would generally say the bivy is just a Band-Aid for an inadequate shelter or other gear. You (and me) are trying to compensate for a poorly designed shelter for the conditions you are in.

in this blog post, Are Bivies Obsolete

 

[Ben C]

I fall into Nick’s camp on this one.  High humidity here in the east often results in a soggy quilt in the morning.  The few times I have used one in the west have had similar results at times.  Solid tarp coverage works better for me.  In super high humidity that we sometimes see in the east (think sleeping in a cloud), you get damp no matter what.

The one time I did appreciate a bivy was a night in the Winds when a snowstorm came up and blew into the tarp all night.  I think that was the only time I have been happy to have the bivy.  It collects dust now.

[W I S N E R !]

Try as I might, I think I’ve come to the same conclusions Nick.  Little to be gained and much to be lost from minimal weight savings.

I shouldn’t have to consult oracles, astronomical data, or the fates to know if a part of my sleep/shelter system is going to keep me dry. : )

[Jerry Adams]

Good post

I found some polycro in the garage (for a window, wife bought from Goodwill).  That works really good, I’m a convert.  Thanks to Nick and others.

After a few trips it started delaminating.  No big deal, I have plenty more and can just replace it.  Oh, nevermind, I just never separated and was inadvertently using a double layer.  Wow, that’s really light, 1 ounce now.

Open tarps like yours – doesn’t work for me.  Occasionally it’s windy and rainy.  Invariably the wind direction shifts  Of course I live in the rainy PNW rather than a frickin desert.  : )

I like the tarp to go close to the ground all the way around – e.g. a pyramid tent.  Most of the time I leave the door totally open for good ventilation.  That’s functionally very similar to an open tarp.  Maybe 5% of the time it’s windy and rainy so I close the door.  That’s an important 5%.

Like I said, I’ve suspended fabric in the air.  6 feet up.  Four corners stretched out.  (actually, I was seeing effect of UV – after a summer it gets faded and weakened but not too much, my conclusion, I don’t need to worry about this for a backpacking tent.  If I had a basecamp tent for multiple years it would be a problem).  So, even with perfect ventilation, under the wrong conditions, the underside of the fabric gets severe condensation.  If it’s then windy, that will get knocked off onto the outside of my sleeping bag.  Conclusion – outside of sleeping bag needs to be water resistant.

Like you said “If either method appeals to you, whatever you choose is a good choice. There is no right or best way; there is only what works best for you.”  It’s interesting to read different people’s experiences.

[Nick Gatel]

A couple years ago I was backpacking in the Muddy Mountains Wilderness, which is high desert. It was December and the lows were in the high 30’s. I was cowboy camped in the open desert with very little shrubbery. I got up around 3am to pee and noticed the top of my quilt was covered with condensation. Shortly after a slight breeze started blowing. When I woke up around 6am my quilt was completely dry.

[dirtbag]

How about something like MLD duo mid with a Borah gear bug bivy? Gives you some options and minimal weight and minimal pack space.

[Jerry Adams]

yeah, same here Nick, outside of sleeping bag/bivy will sometimes dry out over night

there’s a thin layer of air just outside of sleeping bag/bivy that provides some insulation.  Because of body heat, the outside of your sleeping bag/bivy will be a few degrees warmer than the air, so water will evaporate.

If it’s clear, radiative heat loss will cool down the outside of sleeping bag/bivy a lot more than any warming from body heat so you get condensation.  If you sleep under a tarp or under trees this won’t happen.  Sometimes, if it’s clear and I don’t want to deal with dew in the morning, I’ll just put my tarp up.

Body heat will dry out clothing too.  I’ll wear damp socks and they’ll be dry in the morning.  This goes against most people’s experience on BPL.  If thesocks are wet, the down will get wet, lose loft, there’s not enough body heat/time to dry out socks, maybe over the next night if I have dry socks the down will dry out and regain it’s loft.  This is a screwup I rarely make.

[Erik Hagen]

I found this article that’s been passed around here a few times to be the most helpful on bivies: https://40yearsofwalking.wordpress.com/2011/07/04/the-bivy-condensation-conundrum/

I think if I move back to using one I’d be looking at the MLD Event offerings.

[Nick Gatel]

Event has the same problem as any WPB material… it doesn’t breath well, so moisture can get stuck between the sleeping bag/quilt and bivy. The MLD event bivy weighs more than my Deschutes CF and my Cuben 8′ X 10′ tarp.

[Jeffs Eleven]

jerry, you think maybe your tight shoulder fit keep the air in your bivy warmer since there is no escape except through the fabric.  That heat retention keeps it drier as your body heat expels condensation?  If the shoulders were lose then the heat would go out the top and dew would condense on your bag?

 

If this is so, it seems like a small temp/ humidity window for good performance.  (circling back to bivy not very versatile..)

[Jerry Adams]

that may be, mine is different than other bivies in that regard, tight around my neck

[Kevin Babione]

Just turn the bivy inside out so the moisture collects on the outside…Ha!

[Alex Wallace]

A bug bivy and mid work well for me. If weather is nice I just use the bivy and don’t have to deal with setting up the mid. No problems with condensation and, especially if there’s wind, it’s easier than dealing with a polycryo floor.

If weather is bad then the mid goes up and provides plenty of protection from above while the bivy’s floor mitigates ground level moisture.

When mosquitoes are expected to be bad I’ll swap the bivy for a mesh inner to keep my sanity.

 

[Serge Giachetti]

I bought a bivy a few years ago and experienced what you are talking about within the first couple of nights. In general I found that condensation was worse with the bivy, so I sold it and haven’t looked back. For cowboy camping, I do prefer using a sleeping bag though to seal out those drafts.

[Matthew / BPL]

I’ve spent 25-30 nights in my MLD SL bivy and never had more than a tiny bit of condensation on the breathable top portion of the bivy. I did not use a tarp for many of those nigh. Most of those nights are in AZ in the forest on top of the Mogollon rim with a few in the Sierra and a few in the desert. My bivy has the all mesh hood.

My son uses the Borah equivalent bivy and often wakes up with more condensation than I do. I have noticed that he ends up with his head down in the bivy pretty frequently whereas I try to not let that happen. Also, it’s possible that he sweats more than I do or that the top material Borah uses breathes less effectively than MLD’s.

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