Sleeping Bag Liners and Quilts: Convective Heat Loss, Draft Control, and Practical Benefits

[David D]

In an odd twist, as someone allergic to down I’m largely forced to a quilt below 40F.  The weight penalty for an effective 20F synth bag is severe.  The lightest I found was ~ +10oz over an Apex quilt but gave the most miserable sleep of my life.  To hit that temp rating and weight, it had marginal insulation underneath so was freezing when side sleeping and used 40D fabric to lessen heat loss by being a near-VBL.  So it was freezing and sweaty. (Marmot Trestles Eco Elite, blech)

[Terran Terran]

As long as I’m warm from the top, I can keep flipping. Just not if I’m sweating. There’s where the alpha may help. Not without venting. . Is it Thermarest that has top venting of sorts on a mummy?

It is in the low 40’s F that a draft starts to matter. I’ve been comfortable in a quilt in the mid 20’s. Inside a tent, so there was no wind. Any potential drafts as mentioned can be mitigated with a wider quilt. If your goal is to save weight, it becomes more difficult. It comes down to preference.

[AK Granola]

I’m still a sleeping bag user, for all conditions. I sleep well cocooned and swaddled! Easy to turn and toss because the bag moves with me. And I just don’t want to spend the bucks to try something like a quilt that so many people end up shivering in, or that require straps and buckles and adjustments and whatever. I hate fiddling with stuff. I know I’m in the minority, but my systems work for me.

In above freezing weather, I can get by with a 40F EE bag and a silk liner, with a decent pad and the thinlight pad beneath it (which is my daytime sit/nap pad as well). I wasn’t sure if the 40 bag would work on a recent PCT trip from Tahoe to Yosemite, and even on one night of freezing weather at Smedberg Lake the system worked great. I was super cozy, although I did have a hat on, and my EE puffy. Colder than that or in Alaska’s extended wet chilly summers I have my 20F Feathered Friends and it has never failed me. I will rarely use a silk liner with that colder bag also.

I find the silk liner to be easy to get in and out of, because the silk just slips off; I pull it off and on like you would a sock, rather than trying to insert myself into it. No problem. And it’s soooo cozy! Just as you would have a sheet at home in your bed, with blanket on top, it’s nice to have a sheet camping. But much of the time I don’t bring it in order to save the 3 ounces; depends on conditions. I also like having the silk liner for Grand Canyon trips, because sometimes it’s in the 50s-60s at night and I’ll use just the liner for cover at night.

Much as I appreciate the deeper analysis Ryan does on most things, my own experience gives me the knowledge I need to be comfortable at night in my sleep system, science be darned. Maybe some day I’ll try a quilt, but from what I’ve seen and heard, I’m not convinced they’re worth the high cost.

 

[Terran Terran]

8.8 ounces for the JRB AD90 liner. Roomy footbox. Plenty long. Good quality. Shipped fast. Decent price.  Hard to say how much warmth it adds. It feels cozy.  Comfortable as all heck. IDK. Extra weight. Single purpose, but it’s kinda nice.

[Terran Terran]

11.3 oz for the MLD and the JRB AD90 liner. Comfortable at 50*f. A little confining with my arms inside. No worst than a mummy bag. I can leave my arms out and pull the AD liner further up. Pull it on like AK said. The JRB liner is nice in a 10* quilt. A bit luxurious, but probably not worth the carry for most folks. I could see pairing it with a 40* quilt. I’d rate the combined pair for around 50* to 60*.

[Ian H]

I like the Sea to Summit Reactor liner for cold weather, it gives a little bit of warmth, but probably its main function is to catch the sweat, dirt etc so my sleeping bag stays clean. I wash the liner and tumble dry the sleeping bag after each use. The liner alone was warm enough last week at Tahune hut on the Frenchman’s Cap walk – the 2013-built hut has a hydroelectric heating system and amazing insulation, too hot for a sleeping bag/quilt.

Has anyone used the Western Mountaineering HotSac VBL? It looks good as a VBL liner and potential emergency bivy bag, only 101gm.

[Terran Terran]

The MLD xl liner has an inch more girth at the head and eleven inches more at the foot then the StoS. Using the AD 90 liner inside the MLD liner, I find adequate room for my arms and legs. The same was true using a 20* quilt. With a 10* quilt, l still had plenty of legroom, but my arms were a bit cramped.. In all cases though, I preferred pulling it up to my arm pits and leaving my arms out. Basically forming a fabric bottom mummy bag with a quilt at the head end. Pull the MLD up to stop drafts or down for ventilation. DWR finish, it’ll keep my quilt clean.  About 2.5 oz.  and  11 oz. with the AD90 liner.

[karl hafner]

have used silk liners for years but find they wear out too fast.  The reactor liner is too hard to get into and out of as it is not slippery.  It would be nice it liners could attach at the foot end of bag so they are easier to get into and out of, especially at nite.  I like the liner as it makes it easier to keep the hood open and I still stay warm.  Look forward to more info on liners.  Have used them all the way down to minus 35F.

[Terran Terran]

The MLD is 7D nylon ripstop and pretty slick. Other than wind protection, it doesn’t add much insulation on its own. The AD90 liner sticks to my wool socks. I’ve also thought that it would be nice if it attached at the foot. Not wanting to modify my quilt, I’ve found ways to deal with it.

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