View Full Version : bag liners
Last year I bought a WM Megalight and have been less than pleased with it in the 30 to 40 degree range even though it's rated to 30 degrees. In the warmer months of summer it's perfect. I'm considering selling it and getting the WM ultralight which is a 20 degree bag. Before I do, how much warmth would a bag liner really add and can someone recommend one. Silk or ?
Just Jeff
06-01-2006, 03:20
Silk or CoolMax - prolly 5-7* F
Fleece - prolly 7-10* F
You can also use quilts as bag liners or top bags - much more $$$ than a liner but would really increase the temp range, and give you the flexibility of another whole sleep system when used alone. Get the JRB Stealth and it doubles as worn insulation.
mash-tun
06-01-2006, 10:02
Like you, my Megalight has failed to perform in the 30's. I tried a Jagbag silk liner but it did not help improve the temperature range. I still use one just to keep the bag clean.
DrewNC2005
06-01-2006, 10:08
Wow - I took my Megalite to the freezing mark earlier this spring and had no problems (had on midweight long johns). I did, however, shift all of the down to the top of the bag. Maybe that would help?
Alligator
06-01-2006, 10:48
Liners are a stop gap measure. For non-silk liners, you pay a large penalty in weight for a small extension in temperature. If you can afford it, it's better to have the correct bag for the temperature.
I recently posted that silk long johns are on sale at www.sierratradingpost.com (http://www.sierratradingpost.com) I've seen thrus lean towards the silk liner, more so for keeping the bag clean. But if you're not a thru, IMO the long johns have better use.
Footslogger
06-01-2006, 11:42
[quote=Alligator]Liners are a stop gap measure. For non-silk liners, you pay a large penalty in weight for a small extension in temperature. If you can afford it, it's better to have the correct bag for the temperature.
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Plus ...if you turn in your bag at night the dat gawn silk liner gets all twisted.
'Slogger
Alligator
06-01-2006, 11:50
[quote=Alligator]Liners are a stop gap measure. For non-silk liners, you pay a large penalty in weight for a small extension in temperature. If you can afford it, it's better to have the correct bag for the temperature.
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Plus ...if you turn in your bag at night the dat gawn silk liner gets all twisted.
'SloggerTossin' and turnin' like that could get you a trail name like crocodile or sumthin:D .
Both times I've been cold in the Megalight I was under a tarp in a Bivy. The bivy has a 2 ply Gortex top and I'm wondering if possibly the weight of the bivy is compressing the top of the bag, thereby reducing the loft? I even wore polypro long johns and a down vest to bed. I wasn't shivering cold but just noticably feeling the chill. I might also add that I'm 5' 9" about 155 to 160 lbs (when I'm laying off the cheese danish). I may not be heating up the larger size Megalight (64" gerth) as efficiently as I should.
Alligator
06-01-2006, 16:41
I suggest getting a tape measure and measuring the height of the loft with you in it both inside and outside the bivy. I kind of doubt it will be different. I think you'd be pretty warm in a bivy, as I am definitely warmer in a tent versus the open air, and there is less air to warm in the bivy. This bag has a hood? Were you cinching it down?
Yes on the hood. No, I was not chinching it down. I thought that as well. Maybe I'm just not sealing it up good and tight. I made a new hammock to try out over the weekend. First time sleeping in one. I took my 12 year old son and let him have it the first 2 nights. When I slept in the hammock on the 3rd night we traded bags and he took the megalight and the bivy. He said he wasn't cold at all. So go figure.
BTW, the hammock was a huge hit with my son. You can't get him to go to bed early enough at home. But with the hammock he was ready to go to bed at 6:30. It was quite funny.
Alligator
06-01-2006, 17:03
I think that's the problem you are having. I have found that on all my bags the temperature rating is only true when it is totally cinched. And I always wear a hat to bed because I flip over on my stomach.
You advise, “I ... have been less than pleased with (a WM Megalight) in the 30 to 40 degree range even though it's rated to 30 degrees.” ... “The bivy has a 2 ply Gortex top and I'm wondering if possibly the weight of the bivy is compressing the top of the bag, thereby reducing the loft?”
Everything has weight. Anything pressing downward on sleeping bag filler reduces its loft. The greater the weight pressing down against the filler, the greater the compression.
... “I'm 5' 9" about 155 to 160 lbs ... I may not be heating up the larger size Megalight (64" gerth) as efficiently as I should.”
Good point. The goal to maximize warmth is to have minimum separation between your skin and the inner bag.
Alligator asked, “This bag has a hood? Were you cinching it down?” And, you advised, “Yes on the hood. No, I was not chinching it down.”
Cinching my bag upward, from behind my neck, and also downward, toward my throat, makes a big difference. I don’t like the constrictive feeling so, when warm enough, I usually go to sleep without cinching. If I awaken cold, I cinch both the top and bottom; this warms me up very quickly. Another method which helps me keep warm is wearing something about my neck. A cotton bandana is effective but less so than silk and wool.
I thought about opening a thread asking, “What do you do about the hole in your sleeping bag?” I use a porous scarf long enough to cover my nose. My exhalation warms the fabric. The warmed fabric transfers its warmth to incoming fresh air. A scarf significantly warms my bag. I think the effect of the scarf is even greater than cinching. I do both.
gdwelker
06-01-2006, 22:03
Did you have condensation in the bivy? If so, that condensation is also affecting the down. I spent a night this winter with the bottom half of my down bag covered by a "breathable" bivy, and the top half open to the elements. I woke up with my legs cold, and the bivy damp inside over my legs from condensation. The down was obviously affected by the moisture too.
fiddlehead
06-01-2006, 22:42
I recently posted that silk long johns are on sale at www.sierratradingpost.com (http://www.sierratradingpost.com) I've seen thrus lean towards the silk liner, more so for keeping the bag clean. But if you're not a thru, IMO the long johns have better use.
They (silk long underwear) is also on sale at www.adventurelite.com
We also have silk and microfleece sleeping bag liners and just got a new supplier so they should go on sale soon. (as soon as George gets home from is hike out west)
Anyway, my thoughts on all this are that i think one can hike 3 seasons with a good quality, expensive, 20 degree sleeping bag and add a liner, (silk or microfleece) when you know it will be colder than the bags limits: like the smokies in the spring, maine and nh in the late fall, or the sierras, or colorado, etc. That way, you don't have to buy 2 $350+ sleeping bags, just mail the liner to the proper point on the trail. That's what i do with my Feathered Friends Hummingbird which is a great bag at 1lb 13 oz. and the microfleece liner is another lb when i need it. The silk weight is minimal.
Another solution for the folks like me, who sleep cold, is to boil water and put it in your pepsi bottle, or nalgene or whatever, put a sock over it, and put it in your bag with you. It stays warm till about 4 or 5 am. I've slept out in 0 deg. temps with that bag this way many times.
Alligator
06-02-2006, 00:08
They (silk long underwear) is also on sale at www.adventurelite.com (http://www.adventurelite.com)
Well, the tops and bottoms are running $12-16 at www.sierratradingpost.com (http://www.sierratradingpost.com) I suppost they'll run out sometime:sun .
Anyway, my thoughts on all this are that i think one can hike 3 seasons with a good quality, expensive, 20 degree sleeping bag and add a liner, (silk or microfleece) when you know it will be colder than the bags limits: like the smokies in the spring, maine and nh in the late fall, or the sierras, or colorado, etc.
Sure, I agree with you there. In fact you can do it with an inexpensive 20 degree bag, even into the winter down on the south end of the trail. Be sure your bag is really a 20 degree bag is all.
That way, you don't have to buy 2 $350+ sleeping bags, just mail the liner to the proper point on the trail. That's what i do with my Feathered Friends Hummingbird which is a great bag at 1lb 13 oz. and the microfleece liner is another lb when i need it. The silk weight is minimal..
I have 3 sleeping bags that cost $310 total. They take me from conservatively -10F to 25F to 45F (4lbs 4oz, 3 lbs 1oz, and 2 lbs). But I can understand if someone can just afford one bag at $100 and needs a liner. I did it for several years until I got my winter bag. It's still a weight penalty though. If I think I need the liner I really should just bring the warmer bag. Those are synthetic weights, down bags will be even closer in weight.
Another solution for the folks like me, who sleep cold, is to boil water and put it in your pepsi bottle, or nalgene or whatever, put a sock over it, and put it in your bag with you. It stays warm till about 4 or 5 am. I've slept out in 0 deg. temps with that bag this way many times.This is a good tip to remember.
Alligator
06-02-2006, 00:33
...
Cinching my bag upward, from behind my neck, and also downward, toward my throat, makes a big difference. I don’t like the constrictive feeling so, when warm enough, I usually go to sleep without cinching. If I awaken cold, I cinch both the top and bottom; this warms me up very quickly. Another method which helps me keep warm is wearing something about my neck. A cotton bandana is effective but less so than silk and wool.
A fleece neck gaitor is a nice addition at 2 oz.
There are a lot of different ways to affect the bag warmth. Clothing in particular. Speyguy needs to figure out if he is a warm or cool sleeper. Now, I consider wearing long johns, socks, and a hat as normal sleep wear. I will always do that in my bag unless it's a summer heat wave at night. I find it keeps my bag cleaner rather than direct skin contact. There's no real standard that I know of for sleep attire, but before we start to add things like neck gaitors, liners, and/or hot water bottles, we've got to start with the basics. That's why I asked about the cinching. That is considered standard. Next question would be is he using a pad underneath. That's pretty standard too. So, if you are wearing light clothing, have the bag cinched, are on a pad, and the temperature matches the bags rating, if you're cold it's either the bag or you're a cold sleeper. If you have other bags and find that you are cold at their temperature ratings, it's probably you. Things are confounded until you figure out what type of sleeper you are.