Oct 30, 2011 at 8:19 am #1281308
Over the last couple of days (Oct 27-29) I had a chance to hike a 40 mile section of the AT (Carvers Gap to Kincora Hostile) testing out the latest round of my cuben projects. My base weight was right at 4.0 lbs.
I wanted difficult weather and I was not disappointed. I hiked with precipitation most of the time, both rain and snow. The temp typically hovered in the high 30's to low 40's, but was 28 the last day. It rain through out both nights. I camped at Doll Flats the first night and at Laurel Fork the second. Both spots were nice places to camp. Here are some pics.
Cuben Tarp (2.7 oz) and Cuben/M50 Bivy (3.2 oz)setup at Doll Flats
Doll Flats, me in my MYOG M50 Down Jacket and Blackrock Hadron. The jacket and cap performed extremely well.
Laurel Fork camp – day 2
Laurel Fork camp – close up of Bivy, MYOG M90 800 fp down 3 season quilt isnide (18.35 oz)
Cuben pack (4.25 oz) on the AT in snow
Cuben pack hiking in the snow
Cuben pack straps
Last, but not least cuben rain skirt (1.25 oz)
I have posted these before, but in case missed there are instructions to making the bivy and tarp on my website.
JamieOct 30, 2011 at 8:26 am #1796608
@thomdarrahLocale: Southern Oregon
Very cool. Did you use your own quilt also, if so what did you take on this trip? With the wet weather did you have any condensation issues?Oct 30, 2011 at 8:31 am #1796609
Eugene SmithBPL Member
@eugeneiusLocale: Nuevo Mexico
Great stuff Jamie. You're continuing to go lighter and perfecting your kit and process along the way.
Yeah, what Thom said, how was it managing the condensation?Oct 30, 2011 at 9:18 am #1796623
@xpatrickxadLocale: Upper East TN
Jamie, we seem to be in the same place at the same time pretty often. Its a miracle we've yet to run into each other. haha
That pack looks great! …and that bivy isn't half bad either.Oct 30, 2011 at 10:17 am #1796638
Patrick, I was a bit surprised I did not run across one of us out their. My guess is a few days before with nice weather I would have. I only saw a few hardy shelter campers in the 40 miles though in the rain and snow.
Yes I did use my own quilt, but I modified my original 3 season quilt. I cut the length down 6" (cut out one 6" baffle section) and cut 2" inches from the width. This took the weight from about 20.5 oz to 18.35 oz. The length is just long enough for me. I removed the side width without loosing down so it lofts just a tad more.
The condensation story is interesting. I intentionally used M50 for the bivy as I believe that internal condensation management is more important than splash management. The first night was a real challenge. The fog was thick and it rained all night. My pants legs bottoms were very wet and most of my other clothes were moist.
I slept with the bivy fully zipped, mostly on my stomach with my head turn to the side. During the night I noticed moisture forming by my face. When this happens in the past with my MLD superlight I would open up the hood to help the moisture. I intentionally stayed buttoned up with this bivy to see what would happen. Well I woke up with significant mositure inside. So much that my quilt was damp. I was a little disappointed, but this was an extreme situation.
The next night was almost an exact duplicate with a few exceptions…my bag was now starting out wet, my legs were dry because I hiked in shorts only, and I slept with my head out of the hood. It again rained all night and the ground around me was completely soaked, compared to damp for the night before.
What happens was even more surprising. The temp was mid 30's and I started out chilled as my bag was maybe 50% of its orighinal loft. When the morning came I was warm. My bivy was bone dry, I mean BONE DRY and my bag had largely dried out too. I would say this was probably the best night for moisture management in a bivy I have experienced.
I wish I knew the secret to what made the difference. The second night showed me that M50 can indeed make a great bivy material for challenging rain/moisture. Does sleeping with your head outside the hood really make that much difference?
One other item of note for moisture management is the rain skirt. Where else can you cut weight in such a significant way with little or no performance loss for small cost. During high wind and rain my pants bottoms got wet, but the rest of me stayed dry. The legs dried easily in camp. Consider that most rain pants weigh 5-10 oz and that a kilt is just over an once and can be used as a small tarp to sit on it is definately a keeper.
My rain skirt is real similar to the cloud kilt. I would highly recommend folks considering using one over rain pants.
JamieOct 30, 2011 at 11:18 am #1796653
Daryl and DarylBPL Member
@lyrad1Locale: Pacific Northwest, USA, Earth
You make my gear look very very heavy. Good food for thought.
DarylOct 30, 2011 at 11:33 am #1796658
Who made the cuben pack? It looks pretty sweet, esp. those shoulder straps!Oct 30, 2011 at 12:44 pm #1796678
Tyler, I made the pack as well. The straps are cuben top, 3D mesh on the back side, and 1/4" closed cell foam in between. I was real happy with how they road, but i never really carried much weight. I did load up on water (3.5 liter or ~7 lb of water), but even then I had less than 13 lbs in the pack.
The pack is larger than I needed, but I sized it up because I wanted a pack that could hold my winter pad.
JamieOct 30, 2011 at 6:01 pm #1796812
Very nice set of gear Jamie
What do you mean, head in hood first night = bad condensation, head out of hood second night = little condensation?
I don't understand what you mean head in and out of hood?Oct 30, 2011 at 6:38 pm #1796833
Jerry, What I mean by head in hood is the bivy is fully zipped closed with my head inside. Most of the moisture is venting out the netting. The hood stays off my face by the shock cord. When I sleep like this I notice the air around my head is significantly warmer.
Head out of the hood is when I leave the bivy unzipped across my chest. I then sleep with the bivy hood under my head so it is completely outside the bivy. Here is a picture of the bivy unzipped. Imagine me inside and my head resting on top of the hood. The only difference is when I sleep like this I don't use the shock cord.
The two different ways I am describing are not specific to this bivy. I do this with my MLD superlight as well. In the supelight to reduce condensation I open it up across my chest, stick my head out and let it rest on the hood part. This completely leave my head exposed, but means all my breathes are out into the open as well, not into the bivy.
Let me know if this doesn't make sense. I'd really like to hear thoughts. It is strange how one night my bag is soaked and the next night it dries out. With extremely similar temps and precipitation.
JamieOct 30, 2011 at 7:13 pm #1796848
That's what I thought you meant.
I have same experience – any fabric that's above the top of my shoulders has to be flat to the ground, or water vapor from breath will hit it, condense on it, and then get everything wet.
I have to have an insulation layer covering my shoulders to stay warm, but then the outside covering of that will get wet some from condensation.
One thing I've noticed is that it depends on what type of fabric is on that outside covering – standard 1.1 ounce nylon will get wet, fleece gets wet. One fabric that's better is Supplex, I don't know why. I wonder about color of fabric – maybe darker fabrics will get colder and thus have more condensation but lighter colors would be better – must be the next experiment : )
It makes sense that if you had netting over your face it could be a problem – I guess don't do that?Oct 30, 2011 at 7:19 pm #1796849
Paul McLaughlinBPL Member
I believe (though I don't have data handy at the moment) that you lose significantly more water through respiration during a night than you do by way of transpiration (water lost through the skin,also referred to as insensible perspiration). So getting your head out of the bivy means a significant change in how much moisture it has to handle. Perhaps that is enough to explain the difference on the two nights, although quite probably there were other slight differences , whether in temperature, humidity, wind speed, your metabolic rate, or some combination, that also contributed. It does seem to me that condensation – or the lack of it – is about the most mysterious thing I have to deal with in terms of my gear's performance. In what seems like the same conditions, the results are often quite different – just like your experience here.Oct 30, 2011 at 8:23 pm #1796875
Sam FarringtonBPL Member
@scfhomeLocale: Chocorua NH, USA
You are very gutsy. Good for you, for showing how it can be done!Oct 30, 2011 at 9:05 pm #1796898
"you lose significantly more water through respiration during a night than you do by way of transpiration"
Recent threads say the same thing
I'm too lazy to find linksOct 30, 2011 at 10:18 pm #1796926
@davidadairLocale: West Dakota
Interesting. The extra warm air captured with the net hood up is a plus for comfort. The exhaled moisture getting into the lower part of the bivy doesn't help things much though. Would a piece of fabric added at neck level to form a curtain separating the air in the head and body areas help?
Neat stuff, thanks for sharing.Oct 31, 2011 at 6:53 am #1796986
"Would a piece of fabric added at neck level to form a curtain separating the air in the head and body areas help? "
Would that curtain fabric get wet, then wick water to your insulation?Oct 31, 2011 at 7:34 am #1796994
@davidadairLocale: West Dakota
Jerry – Yes, I see how a curtain might tend to get wet and wick water to your insulation. But the warm air trapped on the body side of the curtain might be enough to minimize that condensation? Seems like a little condensation at the neck might be preferable to more in the body area. Does your experience suggest this is a bad idea?
btw I rarely use a bivy… but the inter nerd is intrigued.Oct 31, 2011 at 8:20 am #1797004
Christopher ZimmerBPL Member
Great looking gear Jamie, I really like the pack! It looks like you did a fantastic job on the shoulder straps, keep up the great work!Oct 31, 2011 at 9:30 am #1797025
When it's near freezing which is the worst condition, I cover my shoulders with insulated layer. Am experimenting with different fabric and colors outside this. Make sure that above my shoulders nothing sticks up more than an inch or it tends to collect condensation. There is still sometimes condensation.Nov 16, 2011 at 6:13 pm #1802546
Just reading through this thread and was wondering what effect a non breathable waterproof layer may have as a separating curtain. Would stop the quilt getting wet but may not allow air circulation to help with condensation.Jul 14, 2013 at 11:23 pm #2006161
Tent makers are you watching this?
12oz for a simple fully enclosed tent, make it out of cuben and it would weigh 6-7 ounces…
good job.Jul 14, 2013 at 11:38 pm #2006165
Michael, did you make this?
Can you tell us more about it?Jul 15, 2013 at 5:19 am #2006183
– -K.T.- –BPL Member
I had forgotten about this dead thread.Jul 15, 2013 at 11:05 am #2006282
I got the image from the op's website. Yes, full floor and insect netting. It looks like a great tent, if it were me I'd want the front entry to be an extra 1 foot taller.
Make it out of cuben and the zpacks hexamid would have a real competitor in weight.Jul 15, 2013 at 11:30 am #2006289
I just emailed bora Borahgear about making this tent, or sort of a roomy bivy. It does look storm proof, and simple to setup.
I'm not a massive fan of bivys, for the lack of living space. I enjoy reading a book at night, the shelter above looks like a good compromise.
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