Well, I've been curious about the NA in winter, and the extreme cold we've been having was too much to pass up. If I could handle these temps, no worries hooking up the snowshoes and heading out. So, what to do? Simple, head out to the backwoods by the house and give it a go.
Basic equipment; a Trangia alcohol stove, the Clark NA and a military 3 piece sleep system. No pad, and just stuffing some misc stuff in the pockets. The tarp is the XL, and while not huge, does a reasonable job for me. I pitched one side held low to cut wind from the west. The east side was up to make a canopy to cook under. Gotta have a hot drink before bed.
Before heading in to bed, I lowered the east side a bit, but not as steep as the other side. I figure this may hold in heat a bit better. This is really cold, am I nuts? I was a bit concerned about condensation, so I did not use the outer bivy portion of the sleep system. I used to two sleeping bags, which nest into each other and just the NA. Surprisingly, I fell right asleep and was feeling pretty good. About 2AM and I woke up, there is a layer of ice on the inside of the weather shield down toward my feet. Above my head, it is clear. Must be hotter there. Overall, It's not too bad in here. My feet are cold, really cold, amazingly cold. Brrrrrr. The rest of me though, is cool, but not bad. Condensation, nope, just the ice. There is a gap between the end of the zipper and the storm shield edge, never noticed it before. Now though, there is a cold leak there coming in. Patched that with a sock. Time to step out for a cup of tea.
Slipping the sleeping bag into the Bivy to keep it dry, slide out and fire up my trangia and heat up some water (still in teh bag and bivy). I figure the tent area can use a boost of heat, so the tea is for me and the rest goes into a water bottle. Back to bed feeling pretty good all things considered. The water bottle inside of the bag does wonders, I slid it down between my feet to heat them up, feels great. I can feel the heat from it all the way up at my waist. This time, I kept the bivy layer on the sleeping bag and zipped up the storm shield. A little tossing and turning, the wind is picking up really bad. I can hear it, but it's not really getting inside... the storm shield, rainfly and my sock are keeping it fairly bombproof. I have not closed the rainfly around the hammock, I suppose I could.
5AM and I wake up to a dog barking. All in all, I wouldn't say I'm warm, but I'm not frozen either. A bit on the cool side, but bearable still. A quick pull on my hood to cinch it up and back to sleep for a bit. 7AM, time to get up. That was not a horrible night. I checked the temp logger, and it got down to 9F. That's pretty darn cold, and I made it without heading back to the house, that's pretty respectable. Ok, the hammock now officially replaces the tent for winter camping. Oh yeah, no condensation problem with the bivy bag used, but it did add a few more degrees of warmth and kept my feet from freezing again.
Your mileage may vary, but for me, it's a great winter shelter.