Combine a 20F and 40F sleeping bag?

[dc9mm]

I have a Kelty Ignite Drydown 20F bag and a Dicks Sporting goods 40F sleeping bag. Both mummy style but the 40F bag is larger. So if I use the 2 bags the 20F inside the 40F would that at least make it comfy for say 20 to 30 F air temp? oh Iam using Nemo Cosmo insulated sleeping pad. I don't think it has any R value rating as they don't rate theirs. Tent is a Alps Mountaineering Extreme 2 .

[Fred]

Re: Combine a 20F and 40F sleeping bag?

The nested sleeping bags sound OK, I think. Nemo rates the Cosmo pad at 30 to 40F, which is not quite enough for 20F, so adding a closed cell foam pad, like the Thermarest RidgeRest Solar, underneath the Nemo would add enough extra insulation. Sleeping in dry long-johns might help too.

[a65hoosier]

Re: Combine a 20F and 40F sleeping bag?

dc9mm - Great info provided in your question. My son uses the double bag method on his winter/below freezing Scout trips (they trailer the gear in so he's not hiking/carrying 2 bags). He has a synthetic insulated mummy bag rated to 32 and a larger heavier, rectangular coleman synthetic bag rated at 20. Mummy inside the bigger rectangle bag. He never complains about being cold (and he's been down into the low teens).

Definitely use a properly insulated pad, and as Fred advises above, it wouldn't hurt to use something like the Therm-a-rest Ridgerest Solar (or similar closed cell pad) under it. In fact, both my son and I use the Ridgerest Solar under our Therm-a-rest insulated pads when the temps are expected to go below freezing. Combining the 2 pads, we get an R value of 10.3 under us. I think you'll find the double pad use fairly common in really cold temps. It allows a camper to use a decent insulated pad for most of the year and add the less expensive closed cell pad only when it gets really cold and the regular pad could use that boost.

Of course, sleeping in dry fresh warm pj's and socks (preferably not cotton anything) will also boost the insulating value of the overall system. Bag's temperature ratings include the user wearing basically...longjohns. They also vary by user as each of us sleep comfortably at a different temp.

Combining the 2 bags might be too warm for you at the temps you indicated, but it doesn't hurt if you have the ability to completely "double up" if you find yourself cold. Unzipping the larger bag and using it as a blanket over the mummy bag might also be a good option so you can kick it down or pull it up to dial in the comfort as the temps vary. Eventually, you will come to know what sleeping system combo of gear is right for you to sleep comfortably through the night....no matter the predicted forecast/temps. Doubling up bags is a good way to experiment safely.

Don't forget to eat properly and use the bathroom before bed. All the insulation in the world won't help if your body isn't generating heat for the insulation to capture and hold.

Hand warmers are a nice inexpensive thing to have down by your feet, etc in the bag with you. Those leftover warmers in the bag? Fish'em out. They make a nice warming addition down into the boots first thing in the morning before you have to "boot up".

[dc9mm]

Re: Combine a 20F and 40F sleeping bag?

thanks for the help. I do have one of those reflective heat pads too. I wasn't going to bring it along BUT I guess I better. I will be kayaking to campsite so I will make room for heat pad.