So I know this is going to get some laughs but try to take me seriously here....

I'm an avid camper. My girlfriend... is not. We went for an April trip in the Adirondacks. The result? She's decided she wont go camping again till we find a double sleeping bag...

So there it is... does anyone have any advice on a double sleeping bag that..
A)Works.
B)Doesn't weigh more than 10lbs.
C)Will actually fit into my pack.

I don't think you need a double sleeping bag since most bags will mate with another bag of the same brand. About a thousand years ago, when I took trips with a girl friend, I had two North Face rectangular bags -- one with a left zipper and one with a right which zipped together to make a comfortably large "double" bag. This way, she still had to carry her own weight. Worked fine until I got married and my wife made me quit backpacking with my girlfriend.

Most bags from most major manufacturers will zip together to form a double-sized bag - Some manufacturers even different bags will zip together. Check before you buy them, and just buy two matching bags.

Just be happy your girlfriend wants the double bag

Instead of a double bag, think of two bags that zip together. As Phat says, most manufacturers make 'mateable' bags. If Mummy style, they have to be righthand-lefthand for the hoods to work. The problem with mating mummy bags is the zippers get uncomfortable if you want to get frisky.

For the last 10 years, Phriteaux and I have used two semirectangular down bags from Feathered Friends(for cold weather)or one such bag with a zipped-on bottom sheet (for moderate weather - to freezing) Each bag weighs about 2#. We carry one each, then put them together at camp. Using only one bag with the bottom sheet is pretty lightweight, about 2.5#, total. As the temperature approaches 32F, we put the sleeping pads inside, on top of the sheet.

LOL

Hate when that happens!

Serious question though. . . with these bags that zip together, I need a tall bag, and my girlfriend would probably do just fine with a 5'6" length bag. I don't see how that would work. The bags need to be the same length don't they? Kind of a shame from a weight savings perspective.

Although, is it possible to get away with lighter bags due to the shared body heat?

Here's a solution that might work for you. My wife and I do this.

Use a sleeping bag on top (opened up so it is a flat quilt) and a piece of uncoated nylon on the bottom.

I sewed a zipper to the nylon so it can be zipped to the top sleeping bag just as you would with a second sleeping bag (as described in some of the other responses).

You could simply sew the bottom nylon to the sleeping bag if you wanted to save the weight of the zipper.

This combo of bag and nylon bottom weighs much less than two sleeping bags and is quite warm. My Feathered Friends bag weighs about 2 lbs and the zippered bottom weighs about 8 ounces so the combo comes in at about 2.5 lbs total for the two of us.

Here's another option to keep the weight down. Yes, "marry" two sleeping bags together and Grand Trunk makes double size blankets-inserts for your sleeping bags.
Hope this helps!
Chad

You might look at this idea from Western Mountaineering. A semirectangular down sleeping bag designed to open as a quilt for two. They have a zip on kit that completes the job with making a bottom and holds 2 mattresses.

====== from www.westernmountaineering.com ======

Alder sleeping bag model

5 1/4" Spacing/Continuous Baffles
5" Loft, 25° F
62"/ 4 6" Shoulder /Foot Girth
16 oz. Down Fill
Zips to Summer Coupler
1 lb. 15 oz. Total Weight

For those mild nights when counting shooting stars is all you have to do, then the semi-rectangular Alder MF is your bag of choice! Roomy enough for comfort and warm enough so you won't wake with a chill before dawn. This bag has a 62" shoulder girth and 46" at the foot. The Alder MF has a zipper along the side so that it can mate with mummy bags and a zipper around the foot so that it can be opened flat as a comforter or zipped to our Summer Coupler to be a sleep for two. This bag was formerly known as the "Aspen MF". Nothing about the bag has changed except the name.

============= end =======

I know where you can get one on good clearance. They were listed in a Westernmountaineering Clearance sale on backpackinglight.com. Last I heard, there was one left in stock, but the deeply discounted sale price may now only be a well discounted sale price.

Can you use just a sheet of nylon on the bottom? Does Just the pad hold enough heat to stay comfortable?

Yes, it works for us. We have used it down to low 20s in a tent.

With the nylon bottom zipped (or sewn) to the sleeping bag top it is easy to take up slack in the floor, thereby keeping the upper bag snugly in place over us and on the sides of us.

With down insulation on top and all sides the sleeping pads under us are sufficiently warm for the whole equation to work. The upper bag does have to be large enough to cover the tops and sides of both people, however.

Compressed down under a sleeper doesn't provide much insulation anyway. On an older bag that I used only for me I massaged all of the down under me to the sides of the bag and then sewed the baffles so it couldn't return. No problem. That was 35 years ago and I still use the bag.

Hmm. Well it should be in the 30's outside tonight. maybe i'll set up the tent and give that a shot. Give the neighbors something to talk about at the very least.