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View Full Version : question, base layer providing lower temp rating for bag.



Big Dawg
03-31-2012, 20:33
How much lower (temp rating) do you think I'd be able to go in my North Face Flight 35 degree bag by wearing Patagonia Capilene 4 Expedition Weight top/bottom (or comparable)?

My new lighter weight pack only has enough volume to handle my 35 degree Flight, not my 20 degree Cat's Meow. I can't afford a new down bag. My current set-up consists of an old Campmor light-weight top/bottom for camp and for supplementing my bag when it's colder. A trip this fall will push the limits of my 35 degree bag, and I'm trying to think of alternatives to keep that bag in my lineup for colder temps.

I know this is all subjective w/ many variables, but just wanted to hear opinions from those of you that have expedition weight long undies.

Hikes in Rain
03-31-2012, 20:38
Five to ten degrees, perhaps? That assumes your bag (not familiar with it) isn't so narrow that the extra bulk from the clothes doesn't compress the bag insulation. And that the clothes aren't wet!

ChinMusic
03-31-2012, 20:44
Closer to 5 degrees than 10 IMO.

Moose2001
03-31-2012, 21:19
Closer to 5 degrees than 10 IMO.

I'd agree with 5 degrees. A good silk bag liner would give you another 5-10 degrees as well.

stranger
03-31-2012, 21:46
In my experience adding clothing inside a sleeping bag does not result in being warmer.

A sleeping bag is designed to trap the air inside the bag...nothing else.

Then your body heat will warm up the air inside the bag = you stay warm.

If your bag is not suitable for the conditions, the outside air will be able to penetrate your bag and because you are wearing additional clothing, your ability to warm up the air inside the bag is actually compromised and with some people, certainly myself...I would be colder, not warmer...if I add more and more clothing.

Some people believe just the opposite and claim it works for them = add more clothing if you are cold. Just as many people feel the more clothing you wear, the worse your bag will perform.

In any event...assuming you are the type of person who will become warmer with more clothing...you won't gain much warmth from wearing a base weight, even expedition weight, would struggle to give you more than 2-3 degrees. A far better approach would be to get yourself something like a Black Rock goose down hat, or Jacks R Better down hood...also, avoiding sleeping in shelters, sleep in your tent or under a tarp on the ground.

ChinMusic
03-31-2012, 21:59
I have 180° different experiences with clothing in my bags compared to stranger. I can easily get my 30°-bag's rating extended down to 20 with clothing (but that is a down jacket).

My general strategy is to under-bag and over-jacket. YMMV

rocketsocks
03-31-2012, 22:15
A hot water bag or bottle,and good meal(slow burning carbs)before bed,goes a long way...but i din't have the #'s

ScottP
04-01-2012, 00:00
5-10 degrees, as long as it's dry

Chin's strategy is good--add a down jacket

stranger's experience is also valid--if your clothing prevents your bag from fully lofting then it may do more harm than good.

ChinMusic
04-01-2012, 00:09
stranger's experience is also valid--if your clothing prevents your bag from fully lofting then it may do more harm than good.

I will add that I usu use my bag as a quilt (unzipped to the foot box), so there is no compression of the down. BUT, I do zip it up when push comes to shove. I have not noticed it feeling colder once zipped up (some compression). To me, zipped up feels warmer.

My reason for the down jacket, and I mean a robust down jacket, is that I was often cold in camp during "social time". I tended to sleep warm and chat cold until I got my Nunatak.

Miami Joe
04-02-2012, 14:40
Sleep in the buff.

pyroman53
04-02-2012, 15:21
I agree with Stranger to a point. If I did what you're suggesting, my feet would freeze. My body would be relatively warm, but my feet would be cold. Thus, I would add some very robust insulation to keep my feet warm. I'm thinking some down socks or booties. Then, I think it could work for me.

ChinMusic
04-02-2012, 16:04
One of the benefits of wearing clothes to bed is you don't have to put on cold clothes in the morning.

skinewmexico
04-02-2012, 16:29
Adding a light base layer adds about 5 degrees for me. Wow! A set of Capilene 4 base layer costs more than the 15 degree Stoic down bag that was on Steep and Cheap earlier today.

bigcranky
04-02-2012, 18:28
My experience is that wearing clothing helps a lot with extra warmth. In my mind, that makes sense -- insulation is keeping you warm, and added clothing is just more insulation.

But it has to be the right clothing. I can take my 30-F Megalite down into the high teens wearing Powerstretch tights, a 100-weight zip fleece (similar to Cap-4), a down jacket opened up and draped over my torso, from neck to hips, and down booties. Just the base layer won't do it.

stranger
04-02-2012, 22:05
Like I said, there are different views on this subject.

For me...I am most warm when I heat up the interior air trapped in my sleeping bag.

If I wear a down jacket, I hold the heat against my body, thus restricting the ability to heat the air between the down jacket and sleeping bag. Obviously compressing the insulation is a problem, but that's not my issue.

It's kinda like putting an ice block in a two seperate coolers. Cooler A has just an ice block, Cooler B has an ice block wrapped in a blanket. Come back an hour later, which cooler is at a lower temperature? Cooler A of course. But which ice block has melted less? Perhaps Cooler B. Which is better? Depends on the person I guess. Does that make sense?
I also agree that (for me) this does not apply to extremities, like the feet...I too need heavy socks or down booties in extreme cold, but again just for my feet.

Again, I believe a solid down hat makes a hell of alot more sense than wearing expedition weight long underwear if your goal it to inhance the performance of your bag. Also things like good ground insulation, wind protection and a bedtime snack.

ShaneP
04-02-2012, 22:15
I believe that at some point, clothing will insulate the sleeping bag from your body heat, which is counter productive. I sleep warmer in the nude. and I'm a cold sleeper

kayak karl
04-02-2012, 22:18
Sleep in the buff.
your right. been to -5 degrees in my hammock and naked is warmer then even slightly damp clothes. in the winter clothes go from dry (frozen) to damp as they warm up.

ChinMusic
04-02-2012, 22:18
I believe that at some point, clothing will insulate the sleeping bag from your body heat, which is counter productive. I sleep warmer in the nude. and I'm a cold sleeper

Let me get this straight. If your clothing keeps your body heat next to you so well that your bag suffers from lack of heat.............you will feel..........colder?

As LW would say........"whatever"®

Big Dawg
04-02-2012, 23:31
Thanks all for your input.

skinewmexico
04-03-2012, 00:16
I think the CLO testing Richard Nisley has done measuring heat transfer on BPL shoots a hole in the "clothing makes you colder" theory. But hey, I'm a fan of anecdotal science myself.

Big Dawg
04-03-2012, 00:33
But hey, I'm a fan of anecdotal science myself.

ditto.............

ShaneP
04-10-2012, 20:12
Let me get this straight. If your clothing keeps your body heat next to you so well that your bag suffers from lack of heat.............you will feel..........colder?

As LW would say........"whatever"®


You want your body to heat all of the air trapped in the cavities that are created and held in place by your bag and it's insulation.

Would you rather have a 1/16" layer of warm air surrounding you or 3"?

ChinMusic
04-10-2012, 20:41
Would you rather have a 1/16" layer of warm air surrounding you or 3"?

Warm air is warm air. 1/16" is less air to heat than 3"

For the naked-in-the-bag folks to be right the layering of clothes would have to be wrong. I would MUCH rather have a few layers under my down jacket. For the naked-in-the-bag folks to be right, one would have to be bare-chested under that parka.

stranger
04-11-2012, 04:57
Warm air is warm air. 1/16" is less air to heat than 3"

For the naked-in-the-bag folks to be right the layering of clothes would have to be wrong. I would MUCH rather have a few layers under my down jacket. For the naked-in-the-bag folks to be right, one would have to be bare-chested under that parka.

They are not accurate comparisons...however you would be 'warmer' in one heavier down parka, then a lighter down sweater with more layers inside. Layering is not done for warmth purposes, but for versitality and moisture management. If you only had one down garment, you simply would have no choice but to add clothing in order to keep warm, however I don't think we are talking about that, we are debating whether or not to:
- use a lighter bag and hope to achieve warmth by adding insulating clothing
- using a proper bag and sleeping in minimal clothing
If the OP said "I only have this one option and I want to keep warm", then sure, we HAVE to look at adding clothing IF the bag is not performing, simply because we have no choice. But we do have a choice, carry a bag that works well or skimp and hope to stay warm by adding clothing.

Furthermore...if you don't heat up that air inside the bag, including the insulation, because you are holding the heat against your body due to wearing all your extra clothing...what do you think is going to happen if it's 20 degrees outside?

I would rather sleep at the midpoint between 20 and 98.6 degrees than 20 and 85-90 degrees...call me crazy but I suspect if I restrict my body's ability to heat up my sleeping space, then I will be colder, because I have restricted my body's ability to heat up my sleeping space.

If anything, draping a down jacket on top of the bag would make far more sense than wearing one inside...or a down hat!

stranger
04-11-2012, 05:05
Let me get this straight. If your clothing keeps your body heat next to you so well that your bag suffers from lack of heat.............you will feel..........colder?

As LW would say........"whatever"®

Yup...those little counter-intuative things in life :)

It's not an iron clad rule, but it certainly applies to around 50% of people out there, you could be in the other 50%...but to 'disagree' with a fact is somewhat silly don't you think?

I'm not allergic to bees, but a friend of mine is...neither of us is right or wrong, we simply react differently to the same exact situation...amazing isn't it?

Snowleopard
04-11-2012, 09:55
If anything, draping a down jacket on top of the bag would make far more sense than wearing one inside...or a down hat!
Draping a down jacket over the bag is the thing to do if you have a tight fitting bag and the down compresses when wearing the jacket.

Generally physics says layering works, but there are a number of other factors. It probably depends on how well the bag fits you and whether you can seal it well against air leaks. Also, some of this is subjective; i.e., at home I don't like sleeping with warm clothes on. Camping I'll sometimes wear clothes to bed then strip down when I get too warm.

Also, a good insulating pad/mattress is necessary to stay warm, even when it's not real cold.

Lyle
04-11-2012, 11:14
Adding dry clothing inside a bag does add warmth, as long as you do not add so much that you are compressing the down from the inside. What difference does it make if the heat is held against your body by the clothing or the down in the bag, it still is being kept from escaping. Any heat that escapes the clothing, is then held by the down, thus increasing the amount of trapped heat. The more heat that is trapped, the warmer you will be. A sleeping bag does NOTHING to produce heat, it only traps what is already produced and is being lost through convection and radiation. Simple physics - more trapped air, more trapped heat, equals more warmth for you. Now if the clothing or down is wet or damp, all bets off because you are now losing heat via evaporation.

- Consider adding some down booties, they go a VERY long way toward extending the useful range of a marginal bag. Socks can help too, but not as comfortable. Make sure they are dry and loose fitting or you will cut down circulation and defeat the purpose. Also:

- good medium weight balaclava
- Add an extra closed cell foam pad for good bottom insulation. These are light and can be strapped to the outside of most any pack.

Those are the four biggies for extending a bag's warmth.

Odd Man Out
04-11-2012, 11:17
[QUOTE=Snowleopard;1276672 Camping I'll sometimes wear clothes to bed then strip down when I get too warm...[/QUOTE]

Funny, I do the opposite. I lay on top of my bag wearing only shorts until I get chilled (not cold), and then I get in my bag. I learned this from my father. I think his logic is that when you go to bed your metabolism is ramped up and you might even over heat and start to sweat if you get in your bag right away. As pointed out above, even a little dampness inside the bag can really make you feel cold. Sometimes I go to sleep on top of my bag. If I wake up in cold in the middle of the night I just crawl into the bag and I warm up right away. If it's real cold, I don't last too long. But in all cases, crawling into the bag when I'm slightly chilled makes me feel warmer. But crawling into a cold bag when I'm warm, just makes me feel colder. Works for me. YMMV

Lyle
04-11-2012, 11:21
You want your body to heat all of the air trapped in the cavities that are created and held in place by your bag and it's insulation.

Would you rather have a 1/16" layer of warm air surrounding you or 3"?

The only air that contributes to how warm you feel, it the air immediately around your skin, not that that is 3" out in your sleeping bag. What that warmer air 3" out does is hold more heat in to the thin layer against your skin. It makes absolutely no difference if the air is trapped by clothing or down.