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Sleeping Bag Liners

Sleeping Bag Liners


Postby Arthurs Eat » Sun Dec 21, 2014 7:46 am

Hi folks, I have a very decent down three season sleeping bag which I'm not looking to buy another four season bag to replace for winter unless totally necessary. Could anyone recommend a good liner to hopefully bring my bag up to around four season warmth?

Thanks in anticipation.

Calum
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Re: Sleeping Bag Liners

Postby Caberfeidh » Sun Dec 21, 2014 11:08 am

http://www.walkhighlands.co.uk/Forum/vi ... ag#p237699

Just have a search for many discussions on the matter, then get yourself a Buffalo 4-season outer to stuff your 3-season bag into. Brilliant. Dries your clothes and everything.
http://www.lansdaleltd.com/buffalo-4s-outer-sleeping-bag.html
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Re: Sleeping Bag Liners

Postby tenohfive » Sun Dec 21, 2014 12:08 pm

That Buffalo outer looks interesting but at £140 and 1.3kg weighs and costs as much as I paid for my Rab Ascent 700 - a winter bag in it's own right.

If I was looking to uprate the warmth of a bag I'd probably consider a lightweight, 2 season down bag as an inner bag (an approach ptc has mentioned before) but my own method is a bit simpler as I sleep cold - just use the Ascent 700 year round. And chuck a down jacket on if it's really chilly.
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Re: Sleeping Bag Liners

Postby doggy » Sun Dec 21, 2014 1:51 pm

I got a Gelert muumy shaped fleece liner fron Go for a tenner, haven't used it yet so can't say how good it is.

I'm sure theres a few videos on youtube about combining lighter bags to keep you warm, and some different down clothes but for the cost you might be better with a more expensive bag.
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Re: Sleeping Bag Liners

Postby bydand_loon » Sun Dec 21, 2014 3:22 pm

I was out for a couple of weeks earlier this year and used the Lifeventure EX3 Silk Mummy Liner in a 3, 4 season down bag, but I quickly came to the conclusion that I felt a lot colder with it, so binned it, probably a personal thing as I sleep with as little or nothing on as possible, I think id rather sleep in base layers than go back to the liner (or maybe I should have gone/tried for a cotton one instead)
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Re: Sleeping Bag Liners

Postby murwilson » Sun Dec 21, 2014 10:08 pm

Think about your sleeping mat first. You lose plenty more heat to the ground when lying on compressed down so a proper insulated sleeping mat\pad combination is going to do you much more good than a liner to start with. A silk liner is primarily to keep the bag clean, a secondary benefit is that it will give you another degree or two extra warmth.

Don't wear all your clothes in a sleeping bag, you'll get cold. A sleeping bag is designed that it needs the heat from your body to get into it for it to work. If you wear lots clothing in the bag it will trap some of the heat, the bag won't get up to its optimum operating temperature and you'll feel cold. If you want\need to wear clothes, loose fitting, like your jammies should do the trick nicely.

If you're still cold, place your down jacket or other shell on top of the sleeping bag, like a quilt.

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Re: Sleeping Bag Liners

Postby tenohfive » Sun Dec 21, 2014 11:21 pm

murwilson wrote:Don't wear all your clothes in a sleeping bag, you'll get cold. A sleeping bag is designed that it needs the heat from your body to get into it for it to work. If you wear lots clothing in the bag it will trap some of the heat, the bag won't get up to its optimum operating temperature and you'll feel cold. If you want\need to wear clothes, loose fitting, like your jammies should do the trick nicely.

If you're still cold, place your down jacket or other shell on top of the sleeping bag, like a quilt.

Mur


I just don't buy this approach. I've heard others say it before and it's no more convincing for me the more times I hear it - it doesn't make sense, and it goes totally contrary to my personal experience. Before I waffle on (at length) here's a TL;DR version:
An extra barrier of insulating material between the warm air and the cold air keeps the warm air in and the cold air out.

The way Mur's argument goes (and he's not the first to voice it, I've heard others suggest it as well) is that you want the air inside the sleeping bag to be warm, so you get this warm bubble surrounding your whole body. And without outside interference, the quickest way to get this air warm is to stop it being trapped close to your skin (by your clothing.) So sleep pretty much naked to warm the bag.

Now if you're wearing a down jacket the heat from your upper body will largely will be trapped. So it'll take longer before the air inside the sleeping bag gets warm. Over time - and at a slower rate than without the jacket - the air in your bag will start to warm (provided the bag has minimal circulation, good baffles stopping the air escaping etc.) But it'll take longer than if you weren't wearing the jacket to warm the bag.

But that doesn't matter. Because the air close to your upper body is still warm. It's being trapped by your clothing. Yes, the areas that aren't clothed will feel colder, but ultimately more hot air is being trapped right against your skin. Well fitted clothing will mean less air to heat - there's a lot less air between your skin and your clothing than is contained in a sleeping bag, so it takes less heat.

And even the best bags aren't airtight. You move in your sleep, you force hot air out of the sleeping bag. Hard warmed air. With clothing you've got an extra layer to stop that heat loss.

Put it another way: it's like saying not to use a second sleeping bag as an inner because the hot air won't get into the outer bag. It just doesn't add up - an extra layer, an extra barrier is always going to trap more heat. Yes, if you disrobe to warm the bag the heat will be shared more evenly around your body but there will be less heat inside the bag - full stop.

The 'jacket as quilt' thing just doesn't make any sense - if draping something loosely over you was the most efficient way of trapping heat we'd all be wearing down ponchos instead of down jackets. And if you move much it'd slip off at the first scratched elbow losing any heat it was trapping (not that it'd be much anyway.)

I'd share stories of my own experiences to support my story but I'm sure those who disagree will have their own. Perception can't always be relied on (mine or anyone elses.) So I'm happy to stick with the beer mat science instead.

Oh, I agree about the sleeping mat though - down when compressed (under you) offers virtually no insulation. Your sleeping mat is the only insulating barrier between you and the cold ground.

(And Mur, whilst I've at length disagreed with almost everything you've said - it's nothing personal, and I'm just sharing my view for the same reason we all do on here - to try and help out others. So I hope there's no hard feelings :) )
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Re: Sleeping Bag Liners

Postby Giant Stoneater » Mon Dec 22, 2014 11:06 am

If your unsure how sleeping bag/clothing/liners will work ok,sleep in your back garden on a chilly night no tent just the sleeping bag and yourself ,better if your got a couple of clear cold nights then you can try the various options and see what works and what doesn't.
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Re: Sleeping Bag Liners

Postby Mountainlove » Mon Dec 22, 2014 4:47 pm

I have a fleece sleeping bag liner which works great and for when I have the car near by, I actually take a single duvet! I sleep in my 3 season sleeping bag and put the duvet on top..with that combination I camped in -10 without any problem at all 8) :D
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Re: Sleeping Bag Liners

Postby Rudolph » Mon Dec 22, 2014 6:34 pm

tenohfive wrote:
I just don't buy this approach. I've heard others say it before and it's no more convincing for me the more times I hearit :) )


Same here and for the same reasons. -but I wonder what it is that leads others to feel warmer with fewer layers on in a sleeping bag

All I can think is that keeping the heat near your body with clothes on means that extremities get left out in the colder bag. Overall you are losing less heat if you keep clothes on but there might be some bits (hands and feet etc.) that are losing more.

Just a thought...
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Re: Sleeping Bag Liners

Postby doggy » Mon Dec 22, 2014 6:41 pm

I've experimented a few times camping sub zero and I've noticed wearing tight thermals I'm more cold especially in the thigh region. If I wear loose fitting stuff or I feel better.
I think wearing a micro fleece might be a compromise, I recently bought Trekmates fleece trousers from Go for a tenner with the intention of pimping up my sleeping bag. I've woke up too warm wearing Rab AL base layer, light loose and fleece.
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Re: Sleeping Bag Liners

Postby bydand_loon » Tue Dec 23, 2014 12:54 am

Rudolph wrote:
tenohfive wrote:
I just don't buy this approach. I've heard others say it before and it's no more convincing for me the more times I hearit :) )


Same here and for the same reasons. -but I wonder what it is that leads others to feel warmer with fewer layers on in a sleeping bag

All I can think is that keeping the heat near your body with clothes on means that extremities get left out in the colder bag. Overall you are losing less heat if you keep clothes on but there might be some bits (hands and feet etc.) that are losing more.

Just a thought...


My (totally unscientific) theory is that I sleep warm, the more I have on the warmer I become and maybe overheat/sweat, as the night cools the sweat dries causing the body to feel colder, less layer's and more room/air circulating around the body = less sweat and nothing to dry and cool on the body

could be complete and utter rubbish, but its my theory and im sticking with it :D
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Re: Sleeping Bag Liners

Postby StevenF » Tue Dec 23, 2014 10:17 am

What tenohfive said :)

I think the reason why a sleeping bag feels warmer without too much clothes is because if you are putting on cold clothes (or if you don't bother getting out of your cold clothes) before getting into your sleeping bag you'll have to heat up your clothes and your sleeping bag, which takes longer.

Same reason why if you are cold and enter a warm room you'll heat up faster without clothes on :-)
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Re: Sleeping Bag Liners

Postby Michael Thomson » Tue Dec 23, 2014 11:46 am

StevenF wrote:Same reason why if you are cold and enter a warm room you'll heat up faster without clothes on :-)


I find this to be a great icebreaker at new year parties.
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Re: Sleeping Bag Liners

Postby Mountainlove » Tue Dec 23, 2014 4:22 pm

Michael Thomson wrote:
StevenF wrote:Same reason why if you are cold and enter a warm room you'll heat up faster without clothes on :-)

I find this to be a great icebreaker at new year parties.


:lol: :lol: :lol: :lol: :lol: :lol: :lol:
Or entering bothies on a cold winters night :lol: :lol: :lol: :lol:
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