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#103637 - 12/01/08 11:11 PM Re: Sleeping bags [Re: TomD]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
I think the vapor barrier concept is worth looking at for going up a mountain or a long arctic expedition. I don't know about that stuff, but for a typical winter hike I would rather take that same weight as wool underwear that can capture that same moisture and provide some insulation as well. Perhaps I'm missing something. I think it must depend on how and when and whether you will be able to dry the wool out again.

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#103638 - 12/02/08 07:32 AM Re: Sleeping bags [Re: Cesar]
phat Offline
Moderator

Registered: 06/24/07
Posts: 4107
Loc: Alberta, Canada
Quote:
Quote:

3) Use multiple bags, and go for a hybrid approach. This takes a little more experience but isn't that hard. I sleep in very cold weather with a -10C down bag, *inside* a synthetic sleeping bag or overbag - typically anything from 0C rated exped bag to a "wally world" basic synthetic bag. it doesn't have to be that warm a synthetic bag - it just adds wamth, and most importantly, puts the frost layer (the depth where it is freezing) *outside* your down bag. This means the down doesn't wet out.


Sorry to bring up an old post and I understand what you are describing but If the vapor is traveling from your skin to the synthetic bag it has to pass through the down so wouldn't you still have vapor "in transit" as you get out of your bag? So depending on the temp couldn't that vapor freeze in the down while your packing up and be exactly what you are trying to avoid or do you do something to prevent this?


Yes, but so what, a little bit of humid air will be ok. 10 hours of humid air condensing inside the bag is not. The point is not to have 10 hours worth of condensation in the bag.
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#103639 - 12/02/08 07:52 AM Re: Sleeping bags [Re: phat]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
It seems wrong to me for the down to be anything but the outermost insulation layer.

I just thought of how I might use a vapor barrier layer. As I said, my preference is to sleep near naked in conditions above a bags rating, and to wear dry wool underwear or a dry wool liner inside the bag when well below a bags rating, but never to the point of sweating. The wool captures the water vapour, and the insensible heat of the water vapour, that your body gives off even when not sweating. There is always some. You need to dry the wool out for the next cold night though. That's the catch. The vapour barrier would be handy if you get caught on a night of extreme cold conditions where for whatever reason your wool is already wet. So you could wear the wool under the vapour barrier in those conditions, to stay warm, but protect the bag also. I think my wind layers might be good enough though, for that remote possibility.

We can get -30F, there is a chance of that, but there's no way I'm buying a -30F bag for that. I'm not saying what rating it needs to be cause I'm not exactly. I've down -30F in the backyard in my 3 pound 20F synthetic bag, but that was just one night and not a true test and I can't remember what clothes I have. I will test it out some more this winter though, then finally get the winter bag I figure out I really need for around here. I'm thinking still 3 pounds, but good quality down.

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#103640 - 12/02/08 11:01 AM Re: Sleeping bags [Re: phat]
Cesar Offline
member

Registered: 11/06/07
Posts: 217
Loc: El Paso, TX
Quote:
Yes, but so what, a little bit of humid air will be ok. 10 hours of humid air condensing inside the bag is not. The point is not to have 10 hours worth of condensation in the bag.


So the following night does the vapor that froze, unfreeze and get pushed out to the synthetic layer as you heat up the bag from the inside? Pretty much starting the process all over again? Sorry Ive only camped twice in below freezing temps and would like to start going out more in winter but would like to to get a better understanding on how you do it without a vapor barrier.
Thanks again.
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#103641 - 12/02/08 05:01 PM Re: Sleeping bags [Re: Cesar]
Jimshaw Offline
member

Registered: 10/22/03
Posts: 3938
Loc: Bend, Oregon
caesar

As soon as you get out of a down bag, while it is warm, press all of the air out of it, <img src="/forums/images/graemlins/grin.gif" alt="" />then loft and do it again, you can get rid of a lot of moisture that built up overnight but is still warm enough to be a gas.

There are a lot of very widely different ideas about condensation and down bags freezing up - I have never had it happen to me at any temp. Its important to remember that water, water vapor and ice can all exist at the same temperature and that it can pass from any state to anyother. It can snow at very low temperatures, and vapor can be in the air at any temperature. <img src="/forums/images/graemlins/tongue.gif" alt="" />

Jim <img src="/forums/images/graemlins/cool.gif" alt="" />
_________________________
These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.

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#103642 - 12/03/08 05:05 AM Re: Sleeping bags [Re: Jimshaw]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
I like that word for when water passes directly from solid to vapour, or from vapur to solid, 'sublimation'. Isn't it sublime? This winter I'm going to do some experimenting in the backyard with multiple nights, leaving the bag outside, and weighing the sleeping bag, and perhaps my underwear if I wear any, at the end of each night. It's just a synthetic bag, but I think they gain the same weight they just don't clump up enough. I'm curious also if -30F rated down bags gain more weight than 0F rated bags. At some point you gotta figure some bags are just too much to handle. It doesn't make that much difference over 3-5 nights, and I certainly wouldn't want to skimp if caught out in -30F.

I think what I would like though, as much for fun reasons as for practical or principled reasons, is I would like to have the clothing and gear and skills to spend the full month or even the full season, of whatever month or season I was hiking in on that particular 3-5 day trip. In that way the only real consumable would be my food. I doubt I will ever have the time for much more than a 9 day trip in the coming years but it should be fun to do some experimenting in the backyard to figure out just how its done.

Of course here in New Brunsick there is enough sunlight and firewood even in January to dry stuff out. It would be interesting to spend a winter up in Labrador. That would be a real challenge, especially the further North and inland you go. It's interesting to think about what would work best on such a trip. There was a fellow that manhauled a big sled on a really long trip, he did that on two trips several years apart. I don't remember him saying much about his sleeping bag. I remember he ate alot of chocolate.

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#103643 - 12/03/08 05:13 AM Re: Sleeping bags [Re: JAK]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
I'm looking for a link on that fellows trip. Haven't found it yet but I found this.
http://infomotions.com/etexts/gutenberg/dirs/etext06/llbtr10.htm

Incidentally my father spent many years after WWII up in Labrador, as a civil engineer. He helped build the Goose Bay air drome, and did alot of surveying with these two Cree indian guides. I remember growing up we had these two HUGE, GIGANTIC, down filled sleeping bags that were wool lined on the inside, and canvas on the outside, and closed with these metal snaps. I can't image that he carried them, unless by dogsled. I could be wrong. I would have liked to have asked more about his time in the woods but we talked about other stuff before he passed away in 1986. He was born in 1921. I was born up there in Port Cartier so I feel a bit of a draw to the North. Love that book by Napoleon Comeau. I have my Dad's copy.

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#103644 - 12/03/08 07:11 AM Re: Sleeping bags [Re: JAK]
alanwenker Offline
member

Registered: 02/04/03
Posts: 812
JAK, I've had similar thoughts and aspirations as your own.

On a shorter trip the amount of body generated moisture building up inside a bag, down or synthetic, is likely to be negligible. However, on a longer trip this moisture build up has got to be a huge problem to deal with. Stegar's North Pole expedition comes to mind where the bags used gained a lot of weight from perspiration build up. I want to experiment more with vbl's, that's the best solution I can think of.

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#103645 - 12/04/08 08:10 PM Re: Sleeping bags [Re: alanwenker]
Jimshaw Offline
member

Registered: 10/22/03
Posts: 3938
Loc: Bend, Oregon
alan

I understand that in Arctic and extreme conditions where it never warms up, moisture control can be a problem. <img src="/forums/images/graemlins/tongue.gif" alt="" />

Vapor barriers, if you can stand them, I can't, can help keep moisture out of your bag. <img src="/forums/images/graemlins/shocked.gif" alt="" />

But learning methods of controlling moisture in your bag and learning to drying it out should come first.

Things like pressing all of the warm damp air out when you get up - twice or three times, and using a tent as a drying rack are important skills if you want to spend a lot of time with down. It can be handled by those who know how, and the others can swear at it because lots of us swear by it.

The Navy had a program where they put very thick insulation on steam pipes to conserve energy loss, but at the expense of all the space taken by the insulation. They kept going thicker and thicker (THICKNESS IS WARMTH RIGHT?) until they realise two things.
1) all of the heat radiated through the side of the pipe HAD to radiate from the outer edge of the insulator - making it warm,
AND 2) Thickness made absolutely no difference because as the insulation thickness increased, so did the radiating surface area.

I have never had any detectable frost inside my sleeping bag in the winter under any circumstances, not even on the shell, but then I do not live in Labrador. In the Sierras -5 is really cold and 10 above is more common.

So with the Navy steam pipe as an example and since all of the heat radiated by your body MUST exit through the outside of your bag, why shouldn't your bag be warmer than the surrounding air and why should water vapor decide to freeze on something without a catalyst like hoar frost?

There are too many holes to shoot in a lot of simplified models of how insulation works and there are vast areas of disagreement and experience of many experienced people. <img src="/forums/images/graemlins/tongue.gif" alt="" />

Jim YMMV <img src="/forums/images/graemlins/grin.gif" alt="" />

I have slept in a blizzard at -40 in a 30 degree above rated bag and a snowmobile suit with no bivy sack and no tent and yes he next morning my bag was a bit crispy as I had been buried in the snow - probably kept me alive. But it was a synthetic bag <img src="/forums/images/graemlins/tongue.gif" alt="" />
_________________________
These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.

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#103646 - 12/04/08 08:41 PM Re: Sleeping bags [Re: Jimshaw]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
Way cool. I'm definitely going to start doing the morning accordion thing with the sleeping bag. Sounds good.

On the vbl thing. What if you wore something like wool underwear or a wool lining inside of a vapour barrier lining, and then dried the wool out during the day?

On the gaining ice thing, I think there was a good paper on that with that arctic expedition in mind. There was a couple of guys that chose to sleep outside of the tent in a snow shelter and they actually did better than the fellows in the tent. I think down here though, somewhat south of the land of the midnight sun, even if we did go out for 40 days and 40 nights we would get some opportunities to dry our bags out now and then, with a good day of sunshine and low relative humidity, then maybe doing the accordion thing during a lunchbreak to give the legs a break and the arms a good workout. <img src="/forums/images/graemlins/smile.gif" alt="" />

A dark colour should help also I think, but it might also make the bag colder at night. The heat radiation thing is a bit of a mystery thing to me when talking about really thick layers and an outer shell. But does makes some sense when you think about it. On average the earth cools down at night just as much as it heats up by day. In the mid-latitudes in mid-winter it cools down even more than it than it heats up. So this means a sleeping bag surface exposed to a clear night sky will be colder than the air temperature. How much? I don't know. Maybe 10 degrees in the extreme for a thick bag, being somewhat heated from within. Inside a tent or under a tarp it would be different. The tent wall might be 5 degrees colder than the outside air, and perhaps 5 degrees warmer than the inside air. It would depend on whether everyone has crawled inside their sleeping bags for the night. Plus there is the whole vapour thing going on and freezing on the inside of the tentwall. Anyhow, I know clear sky vs overcast sky makes a difference at night, on one hand because the night itself will be colder than otherwise, and also because of a little extra offset in surface temperatures, perhaps not so much with a tent. My limited experience with tents in winter wasn't that good however. It mostly helped in keeping the wind down. With it all opened up it was colder but dryer. With it opened up like a cave it was warmer but wetter. It was a bit of a wash either way, but that was only about 10-15F, and it was in the woods and not all that windy.

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#103647 - 12/04/08 08:49 PM Re: Sleeping bags [Re: JAK]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
Hey, I found a link for you guys to be able to read my favourite outdoor book...

http://www.archive.org/details/lifes...orth00comerich
If you click on all files you can access different formats.

Here is a cool story on him and his brother sleeping in the snow. This was on the North Shore of the Gulf of St.Lawrence about 120 years ago. Alot of excellent stories in this book. One story is about getting stuck out on the ice on the St.Lawrence River. Also useful bits like lighting a birch tree as a signal flare, and how its often easier to catch seagulls and crows with a fishing line than fish. The section on getting lost in the woods etc is very informative. Also the section on trapping, and the chapters on eating bear and stuff with the Montagnais natives.

Here goes. Just a teaser...

Sleeping in the Snow

One winter I had my
permanent camp on the border of Lake She-
tagomau, the head waters of the east branch
of the Manicouagan River. About the middle
of February my brother and myself decided to
go on an exploring trip of about two days'
walking, further north, on the lookout for
suitable marten ground. As we were not out
for meat we arranged to go as light as possible,
so as to cover more ground. We each carried
one axe, a quart tin kettle, and sufficient grub for
four days, wrapping this last in our shelter tent,
a piece of cotton ten feet long, by six wide
which made our pack and which we carried turn
about. We made an early start, as we travelled
over six miles on the lake and then took to the
woods, and had a long day's tramp. About four
o'clock we halted to camp for the night. There
was the same old job of clearing the snow, cutting
wood and branches and setting up the shelter tent
in a half circle. When all this was done, my
brother went for water to a small lake nearby. I
got ready to light the fire, when to our discour-
agement we found we had no matches. I usually
carried these in my pockets in a small vial, well
corked, and thus absolutely waterproof. In some
way, probably while chopping or collecting the

wood, I had lost them. Neither of us smoked,
consequently we had no loose matches, although
we fumbled all through our pockets just the same.
Night had now set in and it was well nigh impos-
sible to travel back, besides which we were very
tired, so I proposed that we should have
something to eat and then try and get a little rest
by lying down in the snow. If we found it too
cold we were to get up and walk back the best way
we could to our camp, which we estimated to be
about twenty miles away. We ate some dried
smoked beaver and frozen galettes camp made
bread for our supper, and then set to work pre-
paring our bed. I tramped down a trough in the
snow six feet long by about three wide. On the
bottom of this we laid a lot of the fine branches
we had cut for our camp. Over this we laid half
of the shelter tent, then one of our coats, removing
our shoes and putting them also under us. Then
we both got into the trench, bringing the
other half of the cotton over us and piling on
snow, up to our waist, using our second coat as
an additional covering over our body and shoul-
ders. With a branch in one hand I then swept
over us as much snow as I could and covered our
heads with the cotton, shaking some of the snow
over. For a little while it was rather cold, but
it soon got more comfortable and we went asleep
and to our surprise only woke up at daylight.
On the inside surface the snow had melted and

glazed, retaining the heat, but we felt damp
and chilly on getting out, and had to hurry up
and walk to warm ourselves. We returned to
our camp, and felt no ill effects from our night in
the snow. After that night each of us carried
a vial of matches. I slept in the snow again
after that, but I was provided with a good hare
skin blanket and coton wrapper, and we followed
the same plan occasionally to save the time and
work of making a camp when after caribou or on
a long tramp.

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#103648 - 12/05/08 11:07 AM Re: Sleeping bags [Re: JAK]
alanwenker Offline
member

Registered: 02/04/03
Posts: 812
My very limited experiment with a vbl was in -10F temps and I was wearing wool long underwear. In the morning I was damp, not soaked but just damp, and I quickly got dressed and all was fine. I never felt cold while I got dressed - that surprised me a bit.

I have more issues sleeping in any liner - just the extra layer twisting around, than I do with the moisture retention specifically in a vbl.

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#103649 - 12/05/08 01:46 PM Re: Sleeping bags [Re: JAK]
chuck Offline
member

Registered: 10/01/02
Posts: 83
Jak, very interesting story. Can you please check link as I get a page saying it could not be found.

Thanks

Chuck

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