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Extending sleeping bag ratings
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Andrew McAlister
(mcalista) - F
Extending sleeping bag ratings on 11/15/2011 08:25:49 MST Print View

I'm interested in your opinions on how far sleeping bag ratings can be extended by:

* a bivy bag
* sleeping in your clothes (assuming you'd be comfortable awake in the same amount of clothing

I need a sleep system that will cope with -5C/25F, and I'm trying to work out how much lighter a bag I can get away with (both in terms of weight, and cost).

My existing down bag is an antique, and while it was originally rated at -5, with down leakage and the like, I'm pretty sure it is no longer at that level. So I don't really have a good personal comparison.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Extending sleeping bag ratings on 11/15/2011 08:52:54 MST Print View

bivy will give you wind protection and also add an air space that gives you 5 or 10F additional

there's a thread about layering where most people argue wearing clothes adds insulation

I think it's additive - if you wear 1 inch of loft of some insulation it will double the warmth of a sleeping bag with the same insulation, except you probably get a little compression.

If you have 2 inches of total loft it would probably be good down to 25F, although Richard N. has published some data that shows inches of loft isn't real accurate

eric chan
(bearbreeder) - F
hmmm on 11/15/2011 11:06:27 MST Print View

- clothing inside or on top of the bag will extend yr rating ... just watch out how you do it if in damp conditions
- vbl
- overbag/quilt
- hawt nalgene
- warm partner, preferably not a fuzzy bear

etc ...

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
"Extending sleeping bag ratings" on 11/15/2011 11:46:02 MST Print View

Yeah, I hear that. Over the past 20 years or so I have tried all sorts of things. Most work to some degree. Some work well for one night, etc...

Generally, I use two bags: A 0F winter bag and a 40F summer bag. Both are good down so they are about equivalent, give or take.

1) Make sure your bag is clean. A clean bag will loft a bit higher and perform better. Old down is fine, it breaks down but very, very slowly. It takes longer to break down than the shell, generally speaking. Water does almost all the washing a bag needs; a small, like 1/2-1/3 as much down soap as is recommended twice per year is good.
2) Hang it, don't keep it in a sack. Let the feathers breath.
3) Wear a down jacket/vest and long johns. This will add 20F-30F to the bag's rating in conjuction with a down jacket(dual use.)
4) Use a good warm pad. Or two if you have them. A lot of heat is lost below you. Nor do you want melted snow below you, wet snow is cold.
5) Stay dry. As Eric mentioned, if you use a vapour barrier, make sure it is as close as possible to you, not over the bag.
6) LIGHTLY drape your cloths over your bag. More than one layer may not pay, though. The loss of insulating value due to compressing the loft may hurt you as quickly as you add it. Good down is not very supportive.

In conjuction with the other stuff already said here, you can extend a bag about 30F, after that, you need a different bag.

Rutherford Platt
(tunaboy999) - F

Locale: Mid Atlantic
Re: Extending sleeping bag ratings on 11/15/2011 11:55:31 MST Print View

If your target is 25 degrees, I would get a 30 degree bag + down layers that you would bring anyway.

On a recent weekend trip, I was very comfortable down to 27 in a true 30 degree bag + Montbell UL Parka + down hat + thinlight 3/8 inch pad over my Neoair short. The extra pad insulation is critical to extending a bag.

If you want to go any lower than 20-25F, get a 20 degree bag.

Edited by tunaboy999 on 11/15/2011 11:56:59 MST.

Derek Goffin

Locale: North of England
Extending sleeping bag ratings on 11/15/2011 13:29:12 MST Print View

A hot water bottle in the form of a platy I am carrying anyway, in enough foam cooking cosy, mitts and dry bag to stay warm all night, can weigh nothing and increases calories output in the bag. I havnt had it leak but if it did the dry bag shuld protect me

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Extending sleeping bag ratings on 11/15/2011 14:30:06 MST Print View

As James suggested, you might be well advised to start by giving your current bag a wash with good down soap/detergent. That can do wonders. But note: do [b]not[/b] use laundry detergent!!!!!
Atsko make some good products - have a look at their web site.


Mary D
(hikinggranny) - MLife
Extending sleeping bag ratings on 11/15/2011 15:01:23 MST Print View

I followed the care instructions on the Western Mountaineering website (with much trepidation considering the cost of my Ultralite sleeping bag!). It took about 9 hours (including a couple of water-only runs to get all the detergent rinsed out of the washer first), but the bag came out loftier than when I first bought it!

Piper S.
(sbhikes) - F

Locale: Santa Barbara (Name: Diane)
Re: Extending sleeping bag ratings on 11/16/2011 12:41:59 MST Print View

I have found that if I drape my down sweater over my hips inside my sleeping bag it adds more warmth than if I wear it. It also adds warmth to wear my rain gear to bed.

I haven't found a bivy sack to feel appreciably warmer. I guess 5 degrees isn't enough for me to notice.

It would probably add more warmth if I took a bandana bath and changed my clothes before going to bed since sometimes having some sweaty spots makes me cold. But I get lazy about that. If I can strip down naked in the last rays of the sun, thus drying off in some warm sun, then throw on some long undies after I'm dry, that works really well. But then I have to carry long undies which I try to save weight by leaving home.

I've actually ordered a summer-weight quilt to try to wear as a blanket inside my 20-degree quilt. I'm going to test it on my next trip later this month, weather permitting.

John Vance
(Servingko) - F

Locale: Intermountain West
More warmth on 11/16/2011 13:01:18 MST Print View

Since this last spring I have been using a 16 oz quilt down into the mid 20's with great success. This has been combined with a ul7 synmat and the items that I normally carry with me.

I sleep in long silk weight undies and add clothing as needed. I have found that draping my vest over me is much warmer than wearing it and wearing rain/wind jacket and pants adds warmth while cutting down on drafts.

In addition, if temps are expected to be low I wear a down hood (Katabatic Windom 1.5oz), that adds considerable warmth in bed and camp. I find that I sleep warmer and more comfortably if I clean up and put on dry clothes but I understand the reluctance to carry the extra weight.

Making sure that you "fluff up" your bag before retiring helps as well as making sure it is dry. If I have to pack a damp bag I will pull it out at lunch or during stops to ensure a dry bag at night. 10 or 15 minutes in the wind and/or sun can do wonders.