Greetings all. Been a long hot summer here in Indiana and haven't had the energy to do much hammocking. What I did manage to do was make a new dual layer underquilt for my dual layer blackbird. Probably overkill, but it was interesting to make.
I started with one 3/32 inch sheet of Polyethylene foam. Equivalent to 3 sheets of IX. Then I made up the bottom ripstop out of scrap pieces of left over winter camo 1.9oz. Please don't ask - this was purchased at wally world last year and these are all the scraps made into a single sheet. Wally world doesn't have any more of this pattern.
The poly sheet is 72 inches long and 48 inches wide. With 2 inch baffles at the end, the total length is 76 inches. I used poly pillow stuffing for the baffle tubes - 1 oz to each end. Too much stuffing and the baffles won't seal properly.
I then used another scrap sheet of 1.1 oz olive ripstop to make the inner layer - yes, its the same as putting a sheet top and bottom. I only sewed the top and foot and the right side (non open side of BB) and only sewed a 6 inch length in the middle of the open side. This lets me insert more poly sheets or some other insulation that sits between the bottom of the hammock and the inside of the underquilt.
I've only been able to test it when the temps went down to a chilly 63 degrees here, but with a single layer of poly I'm good to the high 40's as tested in another poly underquilt I made. An additional sheet will take me to the high 20's as tested earlier this year. I'm a cold sleeper. With the right clothes I can get to the low teens ok. Added insulation does not slide around. I put the rough side on top.
With only 2 lengths of 1/8 shock cord (2 three ft. lengths) I can hook the ends of the shock cord directly to my whoopie slings using mini carabiners (1 each end). I made the foot end so it will roll over the foot box without squeezing my feet. The long length covers me from head to foot easily - I'm 6' 1". The baffles seal very well. The only thing I have left to do is sew the stretch sides, then it will be officially done.
How much does it weigh? My postal scale says 20 oz. with cords (2 three foot lengths of shock cord) and hardware (2 mini carabiners). Each sheet of poly folds up to the size of a Nalgene water bottle, so for winter camping I can carry 2 sheets no problem. The entire underquilt folds up to the same size as a child's small sleeping bag.
I bought the Polyethylene foam in a 25ft roll at Lowes. Total cost was nothing as it's all scrap put together. It's not pretty, but it does work! If I had to buy the materials it would cost about $38.00 if you use the bargain bin at wally world. The roll of poly is the expensive thing - $25 for a 25ft roll and that's the smallest piece you can buy at Lowe's, but I have enough left over from another project for 2 extra sheets. I love this stuff. Just make sure you punch some small holes in the poly so any moisture from condensation has a way out. I didn't have any problems with condensation, but you may.
Now I just need some cold weather.