Can anyone out there give me an estimate on what the temp rating would be if I added these two bags together? A 25 degree, 16 oz fill, 725 down and a 50 degree, 5.3 oz fill, 725 down, and would it be feasable to add these two together, I hiked a little of the AT last march and with temps in the high teens, I was cold with the 25 degree bag, both bags together weigh only three pounds
fatback
fatback, I don’t know if there’s a reliable method for predicting the rating of the 2 bags together. You already know that a simple liner adds 10 degrees or so. What I can say is that I’ve been comfortable below 0 degrees F by using an ancient Army surplus cotton down bag inside a nylon down bag rated around 40. Anotherwords, the sum can be much greater than its parts!
Brian Osborne
Dear Fatback,
Your question caught my attention because I’ve been wondering what the result would be if I combined a -10F bag with a +20F bag.
Now, you could fuss around with “inches of loft” figures which many sleeping bag manufacturers provide along with their temperature ratings; but, those figures are for their products and so are not really transferable–I would never rely on them and neither should you.
The ultimate answer, for me, is to try out different combinations of equipment in my yard, where a retreat to safety is possible if need be.
If I read your letter correctly (between the lines), you’re planning on long distance hiking next year. If that is the case, you have Fall and Winter coming up immediately right in front of you, which you might use for testing purposes.
Hope this helps.
Conan
Conan
I went through a survival school in the Navy. We were in Maine,close to Rangley. They put us in the woods with 2 down 20 degree bags( green military type) and the nites were -12. It was good enough
Virginian
You’ll want to be careful that you don’t lose the loft of the inner bag. Because after all the loft is what keeps you warm.
I didn’t fully understand this when I put a 35 deg down bag inside one of those cheap heavy Target bags and proceeded to freeze all night.
There are a number of things that you can try. Add a liner like was suggested above. I prefer to take slightly more clothing than needed. I like the REI polartec pants (10oz) and maybe 2 similar material tops. This gives you some additional clothing if you take a zero on 25-30 deg day and are sitting around. Or you can try layering the two bags together like you’ve suggested.
There are lots of other ways to stay warm at night also. Heating up water and putting in a nalgene container has been mentioned other places (of course put this in your sleeping bag). Having a partner to snuggle up with would also keep you warm…
kab21
Dear Fatback,
A few years ago Big Agnes was specifically designing sleeping bags to be used in combination with each other.
You might visit their site and take a look around and see how they combine things and their purported results.
Conan
Conan
Fatback: I have no basis in fact for my guess, but I’d say you’re good to about 10 degrees. Since people’s opinions of temperature vary so widely, I suppose the only sure way is to try it out.
Conan: Where the hell are you thinking of going that you want to combine a -10 degree bag with a 20-degree bag? I estimate that will be good for about 40-50 below zero. That’s my kind of night!!!
Me