Help me! - understand cold weather condensation

[turk]

Thanks for all the advice guys. I think I am officially abandoning the panda hammock. It is a flawed system right from inception. I have never had any condensation problem with my underquilts or weathershield and pad. I was counting on using the panda hammock as part of my partners setup, but due to the relentless condensation issues... its just not worth it. I will stop wasting any more time with it before my subarctic trip. I will now focus on trying to incorporate a VB layer into my JRB system.

I made a last minute decision to pick up a JRB Katahdin in place of the Panda hammock. I am hoping that a WM alpinlite full bag + JRB Nest (used as underquilt) both inside the JRB katahdin - enclosed like a pea-pod, will provide enough warmth, and remain breathable.
Trying to stay positive and keeping warm thoughts.
watching the crazy weather swings up there, daily now.


Cheers. and thanks.

[Just Jeff]

Couple of thoughts.

I have a GoLite breathable rain jacket. Once I wore a wicking T, fleece jacket, then the rain jacket. I woke up with a clammy jacket. The next night under nearly identical conditions, I wore the wicking T, then the rain jacket, then the fleece on top. Made a world of difference...I was warmer and the fleece was dry in the morning. So even though it was breathable, it still acted as a pseudo-VB...be sure to put your insulation on the OUTSIDE of the VB.

Also, material makes a big difference, IMO. I have a hard time with CCF pads, but I've never had a condensation problem with the Exped Downmat. I've even been a bit overheated on the Exped but moisture on the pad wasn't really a problem. Not so with CCF...even when I wasn't overheated I was still uncomfortable.

Which brings me to my last point - every body is different. What works for some doesn't work for another. The science of it stays the same, but it may affect one body more or less than another body, so one person may consider VBs or CCF comfortable while someone else thinks it's miserable. Just gotta test it out for yourself under various conditions and see what works. And hopefully the first test won't be at -90F!!

[BillyBob58]

I will now focus on trying to incorporate a VB layer into my JRB system.

I have never tried to cope at your temps, but my feeling is this is your best approach. Actually, almost required at these kinds of temps. As I said before, just blocking evaporative cooling might gain you 10 or 20*. Far more importantly, all of that body moisture is blocked from condensing ( and freezing ) in your insulation layers.

The other night at 10*F in my PeaPod, I had a space blanket between me and the bottom and side layers of the Pod's 900fp down. There was some slight condensation on the SB, but the down stayed bone dry and puffed up like a balloon. I did not get cold 10* below the pods 20* bottom rating, though by 5AM I was no longer toasty warm.

I hope you are now perusing the VB info at Stephenson's Warmlight. They heve some VB clothing called "Fuzzystuff" that I am thinking about looking into. It can be worn beneath your hiking clothes as well as your sleeping gear. Then you can use lesser thickness of insulation covered with totally water proof rain gear, cheap and effective. For that matter, you could have a waterproof layer over your sleeping bags (as a last resort to protect against precip should something happen to your tent) without worrying about condensation. Assuming you adequately vented your breathing.

Also, I see you have a WM bag. They also sell a neat VB bag liner that is also radiant reflective, if you prefer a liner over clothing. The clothing is more appealing to me, as I would fear getting twisted up in the lining. Plus, why soak your day time hiking clothes with sweat, any more than your sleeping bag? Also, you could not wear your insulated jacket and pants inside the liner, they would get soaked.

Wearing a very thin layer of something between you and the VB makes it feel better, but it is still a bit strange. It feels damp, and at first scary (to me when I first tried it). Damp, but warm! And as Youngblood has pointed out, unless you over heat, your body will only produce so much moisture. At 100% skin humidity, moisture production stops. So you only get damp to a certain degree, barely damp. But if you overheat, you will produce ineffective sweat. That will feel even more weird, but still warm, and the sweat should be kept out of the insulation, a major bonus. After all, it's possible to over heat and sweat even without a VB. It's better to feel strange but warm than to have moisture condense and freeze in your life saving insulation.

It sounds like that Panda bag has effectively a VB, but on the WRONG SIDE of the insulation!

1:skin 2: very thin layer(will get damp or wet) for comfort:3:VB 4: dry( and remains so) insulation, clothing and or sleeping gear.

I think the Stephenson's fuzzy stuff takes care of the thin layer, IOW it's built in.

Is there room for that WM bag and JRB neswt inside the Katahdin without compressing loft? Or would the nest go under the Katahdin?

Good luck!

[turk]

Is there room for that WM bag and JRB neswt inside the Katahdin without compressing loft? Or would the nest go under the Katahdin?

Good luck!

I am interested to find that out myself. Inside would be ideal, but I don't know yet if it will fit with room for loft. Until it gets here, I can't quite picture what kind of suspension I would rig up to hang an underquilt beneath the katahdin, because of its length. I think I will get some higher tension shock cord, and make sure I have several meters to experiment with.

[Peter_pan]

I am interested to find that out myself. Inside would be ideal, but I don't know yet if it will fit with room for loft. Until it gets here, I can't quite picture what kind of suspension I would rig up to hang an underquilt beneath the katahdin, because of its length. I think I will get some higher tension shock cord, and make sure I have several meters to experiment with.

Turk,
FWIW...Couple of guys in MN used the Mt Rogers ( same sizeas the Katahdin) as over bags last year.... Use of the DTEPC will create a full bag with 80+ inches of girth... perfect over bag sizing, at least for th ground types....

Not sure that I'm correctly picturing what you are planning to do though.

Pan