I did it. I sliced into my new Marmot Helium and turned it in to something worthy of being in the mountains in September. It weighs 31 oz, is chocked full of down, has not one cold spot, and is luxuriously wide.
First the bag weighed 35 oz. Then I cut off the hood, the first baffle, the full length zipper, and the zipper baffle. Then it weighed 24oz. Next I took all the down from what I had cut off and stuffed it in to the quilt. Then I took down from my old Marmot Helium and stuffed even more down into it. Then it weighed 34 oz. Then I sewed the seams up and took it to the laundry and washed it. Now it weighs 31 oz. *
This isn’t the ethereal kind of loft you get from having just washed your bag, this is the solid kind of loft you get when your baffles are full of down. If you slept in a shelter with this bag you’d have to say, “Please excuse my loft.”
For this project you will need: thread, pins, scissors, sewing machine, and a mummy bag. Also a vacuum cleaner to clean up with.
To make the seams, I just turned both edges inward, pinned them, and then sewed them up.
Difficulty rating: easy. Tip: I did this with the down dirty—dirty down is much easier to handle than clean down.
*I brought two bags to the laundry and they both came back 3 oz lighter. Which seems like it might justify the weight of a silk liner.
Update: I headed out to the PCT with new quilt in late May. In the mountains above Idyllwild, less than 200 miles from the Mexican border, the temperature dropped to well below freezing, the wind was blowing 50-80 mph gusts and it snowed.
I was camping in Z-pack Heximid tarp which let in a lot of the wind. The bag kept me warm till I rolled over and then I would get cold—I missed the zipper. I think quilts are better for people how don’t move around much while they sleep. Maybe if I had put elastic straps to hold it around my pad or ties…..
Now I carry a Z-packs 10 degree bag with a stretchy liner. Mostly I sleep with it as a quilt but when it is very cold I zip it. I also went to using the Gatewood Cape as a tent because it blocks the wind better than the Heximid.