I had thought about how to make an inexpensive and warm enclosure for my hammock for a while and finally got around to implementing my favorite idea today.
The path I took was to take a poly tarp and tie it around my hammock into a decently sealed combination of a fly, door, and under-enclosure. I don't know if something like this has been done before, but I am pleased enough with the results to share.
The results: higher ambient temperature inside the hammock. It was in the low 30s today and I was comfortable in the hammock (outside the sleeping bag) in a long sleeve shirt. I think it was in the low to mid 50s inside the enclosure after about 10 minutes. Butt was toasty with a pad.
All that is required to make this rig is 50 ft of cord (I'm using walmart paracord) and a 10x8 tarp (mine's the walmart camo one). I am using a 10' hammock, a foam sleeping pad, and a zero degree bag. Here's a diagram of the rig.
When the rig is assembled, the hammock is only accessible from the head. To enter, you must crouch under the fly from the head side, and then put your butt through the door into the hammock, and finally move the ridgeline over your head (bringing your head through the door). Once in the hammock, you close the door by routing (as in the diagram) the doorline down to the stakeline, through the bottom of the doorline, and then securing at the ridgeline (the "latch"). Closing the door like this seals the fly against the cocoon. No part of the hammock is left exposed to the wind. Undoing the latch knot at the ridgeline opens the door back up for exit.
Benefits that I see with this design: very low cost, an air-gap between your butt and the wind, highly weather resistant, and low amounts of draft. The cocoon part can act as storage or a place for secondary insulation like an underquilt. Less importantly, it also requires only two stakes to secure against high wind. It requires only 4 knots: two for the ridgeline (requires a ridgeline), and two for the door. It can be stored partially assembled.
If you guys have seen something like this before, could you point me toward it? I'm interested in seeing how something like would be improved (EG, warmer for cheap). Thanks a bunch.