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Best 2-bag Sleep System for Deep Winter?
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rOg w
(rOg_w) - F

Locale: rogwilmers.wordpress
deleted on 06/26/2013 06:18:33 MDT Print View


Edited by rOg_w on 09/08/2013 16:23:22 MDT.

Max Dilthey
(mdilthey) - M

Clarification on 06/26/2013 08:26:37 MDT Print View

Thanks for the measurement Rog, but I don't own any WM bag yet, and I can only buy one.

It looks like the measurements are the following:

Mountain Hardwear Ultralamina 45º: 60in Circumference

WM Highlite 35º: 60in Circumference

WM Megalight 30º: 65in Circumference

EMS Solstice 20º: 62in Circumference

2 inches isn't too bad on the Highite, but Megalight may be the way to go.. I can probably use the HighLite as an outer bag. Will cold spots prevent deep winter use, or are the sewn-thru baffles not a big deal if I have a coat and the 45º bag?

Dharma Dog

Locale: The Louisiana Swamp
Re: Clarification on 06/26/2013 08:32:36 MDT Print View

FYI - Western Mountaineering bags including the Megalite are on sale right now at

Max Dilthey
(mdilthey) - M

Sale on 06/26/2013 08:53:26 MDT Print View


Dustin Short
(upalachango) - MLife
Re: Sale on 06/27/2013 14:45:24 MDT Print View

I would get a 20F bag with full baffling like the WM Ultralite (I do own it and love it).

This is my reasoning:

With a a 45synth bag you are covered for wet summers. When the temp cools down a bit you can supplement with puffy clothing and probably get down to freezing easily (and the puffy clothing is nice in those chilly morning/nights). This I think is near your rationale.

Going from above freezing to below is a huge difference in perceived temp, because now you're body is moving from fighting hypothermia to fighting frostbite. So getting a 30F bag only lets you "play" around this significant temperature. You usual light insulation clothing for near freezing temps will let you push your bag colder, but you won't get the same 10-15F boost as you do when temps are all above freezing mostly because quality light 30F bags have sewn through baffles (as in the 45F down to freezing).

This is where I advocate a 20F bag. It gets you well into freezing temps. When the forecast calls for freezing nights, a 20F bag is warm enough to sleep comfortable should those all too frequent cold snaps occur, but not so warm that you can't sleep in 40F temps too. Then if you need, you can push a 20F bag down to 15F or 10F with light puffies and even further if you go with heavier weight insulation as forecasts dictates.

If you can take a synth 20 bag down to -10F with your MHW 45F then a proper 20F down bag will take you to same temps if not colder, with a considerable weight savings.

So with these two bags you will have solid coverage between -10F and 55F or so (based on your experiences) which is impressive. There really aren't too many holes in that range where you'll be uncomfortable, especially if you supplement with your clothing. It will make your EMS bag redundant but sell it off to friend or keep as a loaner.

Now for a specific bag, the WM UL has a trick, it's actually EN rated to ~16F and thus a very warm 20F bag for a full pound savings on your EMS. It is pricey but I've not regretted my purchase once (ok, maybe summer in the desert...but a MYOG quilt is in the works). I've slept as warm as 50F in it and it vents well enough.

For reference this is my system; unfortunately I don't get many chances to test "really" cold temps or soggy conditions in the desert so take with a grain of salt and I am conservative since I hate the cold (although slowly adapting). Pretty much the WM UL for all temps I routinely see. In the heat of summer I've got the synth quilt in the works which will also be used in wet conditions. If the forecast calls for 20F but I'm at elevation, the synth quilt comes along as extra protection for cold snaps. With appropriate clothing for the season I'm fairly confident that I can get down to 0F using these two (my synth quilt is lighter than a MHW 45F). I'm sure playing with VBL would go further. I did just pick up a 0F bag to test this upcoming winter but I expect it will be relegated to deep WY winter conditions or high altitudes since the rest of my system is so versatile.

Max Dilthey
(mdilthey) - M

Woohoo! on 06/27/2013 14:52:42 MDT Print View

I think this is probably the most helpful post possible. Your insight with the difference between 20 and 30 is invaluable. Thank you for taking the time to write this. My question is essentially answered.


Raymond Estrella
(rayestrella) - MLife

Locale: Northern Minnesota
Best 2-bag Sleep System for Deep Winter? on 06/27/2013 18:37:01 MDT Print View

I agree that a bag/quilt combo will give you move options and a greater range of use. Check out this review I did of a 0 F bag:

I used a couple different quilts with it. My son too has used some of my quilts along with his 20 F Sierra Designs bag to take it below 0 F a few times.

Enjoy whatever you do decide to get.

Eric Blumensaadt
(Danepacker) - MLife

Locale: Mojave Desert
Synthetic outer, down inner on 06/28/2013 14:09:34 MDT Print View

My extreme cold weather system is an older -20 F. MH Polarguard insulated bag with a zippered expanding gore so I can insert my WM Megalite inside. This combo does not compress the down bag and is not restrictive.

Down inside and synthetic or DWR treated down outside means that your body moisture, when migrating to the outer layer (& THEN CONDENSING), will be in a layer that is not as much affected by moisture and likely let the frozen moisture at least sublimate off to the atmosphere when the bag is aired. Further, double bags can be separated for better airing.

Personally I feel every down winter bag should have the down fill treated with one of the new down DWRs. Patagucci seems to have one of the best of thse treatments but, Mon Dieu! the $$$.

Edited by Danepacker on 06/28/2013 23:06:00 MDT.

Raymond Estrella
(rayestrella) - MLife

Locale: Northern Minnesota
re: DWR down for winter on 06/28/2013 20:37:31 MDT Print View

"Personally I feel every down winter bag should have the down fill treated with one of the new down DWRs"

Why? At -20 F you aren't going to fall in a creek or get caught in a rain storm.

If you have condensation in the bag freeze, it will do so in whatever insulation you have, DWR or not.

I like the tech, but don't see it useful/needed at extreme temps.

Eric Blumensaadt
(Danepacker) - MLife

Locale: Mojave Desert
DWR treated down for winter bags on 06/28/2013 23:12:21 MDT Print View

My Dear Raymond,

Down bags in winter have the dreaded "outer shell condensation" problem. Believe me, without the ability to get rid of this frost your down bag gets progressively heavier each night, eventually becoming unstuffable and unuseable over weeks. (See Scott's disasterous South Pole attempt).

A DWR treated down MAY let this frost detatch from the down more easily and MAY sublimate if exposed to sub zero airing daily. (I'm surmising here.)

I've experienced frost buildup in both down and synthetic in sub freezing weather over many days. It ain't fun and it ain't warm.

Raymond Estrella
(rayestrella) - MLife

Locale: Northern Minnesota
frost on 06/29/2013 03:09:32 MDT Print View

Yes, I know that Eric. (And it happens with any bag, not just down.) The only way to "get rid of it" is to let the bag thaw so you may be right that it could help there. But when it never gets above freezing it would be hard to get to the point of needing the DWR down, right?

Well I am off to Paul Bunyan State Forest for a few days. No frost in the forecast, just heat, humidity and huge mosquitoes. Have a good weekend.