You don’t need to spend $100 or more on a good winter sleeping bag to stay warm. Especially when you will most likely only use it 2 or 3 times a year, and who wants to store that. I’ve found after about 15 years of camping with the Boy Scouts in both Michigan, and Florida. This works much better.
Items your going to need.
2 - 40* or warmer sleeping bags (if your sub 0* camping)
40* sleeping bag and a polar fleece sleeping bag (the polar fleece bag will add about 25* to your bag)
A sewing needle
thick thread or embroidery floss
2-3 Diaper pens (they have to be diaper pens you can get them from the baby section at the store or like Babies R Us where they sell the cloth diapers, because regular safety pens come undone in the middle of the night and stick you!)
Place one of your sleeping bags into the other one, if using a polar fleece bag place it into your regular sleeping bag. Making sure to push the inner one tightly to the bottom of the outer one. So the zippers are touching.
Thread your thread or floss threw your needle. Pulling the two ends together, Lick you index finger then wrap the thread three times around your finger. (if your using diaper pins skip ahead to step 11
Then rub the thread down off your finger with your thumb. Then pull the ball you just made tight. You now have a large knot.
Pinch your two sleeping bag’s zippers together at the bottom, then run your needle threw BOTH of the zippers just below the zipper into the cloth part of the zipper.
Pull your thread half way threw the zipper, then take your needle threw the thread as shown, which is between the two pieces of thread that you tied into the knot.
this will keep your knot from pulling threw the cloth in the night or undoing your sewing
Pull your string tight, pulling the knot all the way until it’s touching your zipper.
Repeat about 2 or three times.
Run your needle threw your circle of thread to start your knot, going threw both pieces of thread, then pull it tight.
Then run it threw the part you sewed to the zipper finishing with step 9 each time. Then cut your string. And repeat on the other side, only sewing the bottom zippers together. 2 spots works great but you can do 3 if you really want, any more than that is too much, you just want to keep the bags together while your sleeping.
OR you can pin the zippers together with a couple diaper pins. I’d only use diaper pins because regular safety pins come apart and stab your feet in the middle of the night. I know the picture shows regular pins, but I don't pin mine, so I didn't have any. But, I do have friends who do use the pins and they say they work.
On nights where it’s warmer you can sleep on the inner sleeping bag, giving you more padding underneath you, and zipping up the outer bag to keep warm.
Then on nights where the temperatures are colder you can sleep in both bags.
I spent in 2001 $149 on a mummy down filled bag for my son to take camping which was rated -20* . He came home from camp saying he was so cold he couldn’t sleep. We tried this at his next campout which was A Camp Alaska Campout. Which is where you get what you can fit into a shoe box and your sleeping bag, and you have to survive the weekend with what you have and what you find. Which mean you dig a whole in the snow and sleep there. He loved this bag better! (we used 2 - 30* bags) he had more padding under him and over him. But now we live in Florida and only have to double them for only one campout a year. Because that's the only month it gets lower than the 40* the bag is rated for. We get about a month of around 20's and 30's degree nights. And when the temp.s rise again and you don't need a double sleeping bag we just snip the thread and take them apart. Happy Camping and hope you stay warm.