2 bags combined

“I've got a GoLite Feather rated to 20 degrees F and a Western Mountaineering Hightlite rated to 35 degrees F. I'm just trying to get an opinion on how capable this combination might be in colder weather. Since right now the weather is not cold enough to do field testing I'm asking here. This would be an economical solution rather than buying a third winter bag. All total its about three and a half pounds of bag. I'm guessing its good to at least 0 degrees.”

“It sounds like it should work as long as the outside bag has enough room not to compress the down of the inner bag. I have heard of somepeople just opening up on of the bags ad draping it over the bag that you are sleeping inside.

I am planning on using my 0* bag with my 30* bag inside if I ever need to go really cold.”

“In Jardine's book he calculates the bags temp rating with this formula:

TR=100-(40*L)

L = the half loft of the bag, i.e. the thickness of the bag that is on top of you. You can always measure it and figure it out for yourself.”

“i dunno about that formula DD

2 1/2" = 0* ?

i think it's more like 4"=0*”

“I did just that when I started and it worked for me at well below 0°F. In fact, my expedition weight sleeping bag is probably my most recent purchase since I began (re-began) winter camping.

Warning:
While the bag is an extremely important it is only one element in what must be an efficient system. No bag will keep you warm if it is not isolated from the ground and protected from the elements - or wet inside from body vapour.

This means that in very cold weather (0°F) you need a winter mattress, a Vapour Barrier Liner and a winter-tested tent or bivouac sack.

Also you must have a stove that works at these temperatures. Once again, while the stove is essential it is only one element of the system. Unless you are at altitude you need a naphtha (white gas) stove. Canister stoves did not work even at FYAO in NYS. Also, a canister cannot be protected from the wind unless the canister is remote (can you say BOOM?). It must have a stand and protection to stop it from melting through the snow.

All this is ueseless without knowledge AND experience. You must know how to stay both dry and warm - this means putting on and taking off layers - and knowing how to do it (and having the right clothing) without getting cold. You need to know that polyester liners and fleece clothing are far more effective in a VBL than otherwise warmer down.

You need to be able to re-fill (or switch - my way) fuel bottles in the cold without compromising fabrics (spilling).

You need to know that a butane lighter will not work unless stored close to the body. That you need wide mouthed Nalgenes (carrying them up-side-down never worked for me, but I still do it) and what to do when the water in them freezes. You need to know that you cannot melt snow unless there is a layer of water at the bottom of your pot.

You need clothing for the job. It must be breatheable (Gore-Tex works best when the weather is cold and dry) and have full-length zips that allow you to put on and take off layers without removing your boots or otherwise getting cold. If your clothing is inadequate no sleeping bag system will work. Many people neglect to layer mitts - I use any combination of thin polyester liner gloves, 300 weight fleece mitts and G-Tex overmitts.

Test and practise over a week-end in your back yard. Know how everything works in the conditions in which you will use it.

Have fun.

Doug”