I spent the weekend in the White Mountains with a group of winter hikers from the Appalachian Mountain Club. While they all slept in the unheated loft of the Harvard Outing Club cabin, I camped around back in the woods in my Scarp 1 Tarptent to field test it in snow.
Setup was not as straightforward as I hoped, but that was largely my fault. I had been expecting more snow and had brought some new SMC snow anchors that I wanted to try out, neglecting to bring beefier snow stakes that could penetrate frozen ground. For a while, it looked like I'd have to sleep in the cabin too, but I drove 10 miles south to an outfitter who had the right kind of stakes for sale, had a hot dinner in town, and returned to my camp site to try again.
When I got back, the surface of my site had hardened up nicely and while I was able to pitch the tent, it took a while. I needed to reconfigure the guy-lines to connect to the new sno-stakes and not the 3 season grommet that ships with the tent. Since my hands were freezing, I just ran some of the extra guy-line through the sno-stake holes, tied a square knot and drove the stake into the ground, packing snow over it to make it more secure.
Seriously, try this at home multiple times before you do it for real. I did it for the first time by the light of a headlamp, but could have given up and retreated to a winter cabin. I'm glad I wasn't doing this for the first time where it mattered.
The nighttime temperature during my first night in the Scarp 1 was 2 degrees fahrenheit, with 50-70 mile an hour winds. I was camped in forest which broke the force of the westerly winds and I hoped I wouldn't need the optional wind bracing poles made for this tent, which I hadn't bought. It was snowing as well and a slight dusting of snow was accumulating on the surface of the tent.
I spent the night in a -25 degree Western Mountaineering Puma sleeping bag on top of two pads and was nice and toasty all night. I kept the vestibules closed and piled some snow around the base of the west vestibule, without covering it, to break the wind a bit.
There was zero condensation on the tent walls or on my sleeping bag in the morning after my first night in the Scarp. I was a happy guy.
On the second night, the temperature was much warmer, at 20 degrees fahrenheit, with virtually no wind. I turned in at 8PM after a tiring 7 mile hike up Imp Face near the base of Mt Madison, falling asleep to a cacophony of coyotes yelping in the distance.
I woke up about 4 hours later to pee and found considerable frost on the ceiling of the tent. I opened one vestibule about half way to get more ventilation and fell back to sleep. When I woke 6 hours later, the frost was much worse and covered every part of the inner tent and mesh windows. In addition, the top of my sleeping bag was quite wet. Also puzzling, the damp socks that I had been sleeping with in my bag, were not dry – a clue.
I think sweat from my body, along with the warmer temperature and higher humidity was the cause of the internal condensation. If that is the case, being much more aggressive with opening the vestibules, seems like the proper way to mitigate the condensation issue.
I would also surmise that another rule-of-thumb is to position the tent so that the ends are facing the wind and not the sides. This way you can aggressively vent without experiencing increased convection from the wind. I didn't do this when I pitched the tent this weekend, but I think it would have made a big difference. I could have kept the vestibules wide open on both sides of the tent without feeling the wind blow over me in the inner compartment.
What do you think?