Last week I posted pictures of my home brew modular sleep system...last night I took the plunge to test it at home and despite a touch of the flu I set up on my balcony ready to take on the -23 C weather the forecast was calling for. I was worried that I might have been biting off more than I could proverbally chew by going so cold for the first test.

The test was set up as follows:

• Set up a tarp on the balcony (both to keep things clean and as a bit of a wind break). No overhead cover to speak of.
• Thermarest pad and the bags went on top.
• I set up some gear as I might have in such a situation. Thermos, kits, canteen, cooking gear, some food, space pen and paper, flashlight, etc. Thermos and thermos jar were set up with boiled water ahead of time and the canteen was filled with tap water ahead of time.
• All gear was set up 6 hours before I went out for the night (6pm, I went to bed at midnight) to make sure everything was thoroughly frozen. It was aprox. -13 C when I set everything up.
• I would only be using stuff from my pack. In reality I only took certain things and left the rest inside...this proved to force me to improvise a couple of times (the alternative was getting out of the bag!)
• I would only wear Merino Wool ultralight long johns, long sleeve top, wool socks, and a toque. I's also wear a thin fleece jacket and gloves for part of the test.

There were 3 parts to the test.

• One - Getting into the bag. Would I freeze my youknowwhats off trying to get settled into so many layers.
• Two - Would I be able to sit 1/2 in the bag, prepare meals, etc. Without either top or bottom parts of me getting cold.
• Three - Would I be able to sleep the night all cocooned inside.

Here's my account of how the night went (with some conclusions at the end for those of you with ADD):

Getting in proved to be a bit more tricky than your average sleeping bag but manageable. Fortunately the AMK emergency bivy slides well against the fabric of the bag so making adjustments or hiking it up isn't much of a problem. I velcro'd and zipped everything up around my chest. I was wearing the fleece, toque, and wool gloves.

I got to work attempting to prepare a meal (I'd have gotten really bored otherwise). I was amazed to learn that the water in the canteen had not frozen yet...there was some ice inside but it was still pourable (I guess the canteen being inside cups and that inside the bag provides a bit of insulation). I think had this been a real situation and I was drinking the water during that 6 hour span, it wouldn't have stayed liquid as the less there is the faster it freezes.

I wasn't surprised my lighter didn't work so I dug out the strike anywhere matches. Uh oh! Where am I going to strike them?! I had left a lot of my gear inside and there's no way the alcohol stove would have lit with just a firesteel at that temperature. Fortuntaely my head was right by the valve on my bicycle tire...voila, fire! The coldest I'd tried the stove was about -20 and by the time I went to light it, it was at least that cold. Fortunately the canteen cooker has a cup for holding ESBIT tablets or alcohol gel. I poured some around the stove and lit it...big flame = quicker prime! This of course used way more fuel but I'm OK with that. During the time the stove was running (apro. 20 minutes) my legs were as warm as could be.

Once the Eaterz boil in bag entree was warm enough (aka: When the stove ran out of fuel) I ate it quickly, took off my gloves, my jacket and went to sleep. It took a bit of wriggling to get down into all the bags far enough but didn't take too long IMO. With the bags up around my head I zipped closed the bivy (I could have left it open and the bug screen rolled back but I wanted to test it all), pulled the AMK bivy around my head as much as I could, and pulled the draw cord on the sleeping bag tight around my face so only my eyes and nose were poking out (I later covered my nose with the front of my toque to keep it from getting nipped). My hands were cold from putting away frozen metal cookware and water bottles but they warmed quickly. I had brought a half dozen hand warmers and didn't need them. Once in the bag for a while I did feel a tiny bit clammy but never wet.

I woke 4 hours later. I was pleasantly surprised to feel my toes...usually the first part of me to go numb in the cold. If I wasn't cold why had I woken in the middle of the night? What is it about encasing yourself in a sleeping bag that gives you the need to urinate at the least convenient times?! This was the unplanned stage 4 of the test. Could I get out of all the layers in time without killing or wetting myself. The hardest part was getting my extremities to the zippers...once I was that far I popped out easily and the bags stayed nested in their place without seperating. I felt around quickly and felt no condensation on the mid part of the bivy or sleeping bag. The bug mesh around my face was dripping wet with condensation however. When I got out of the bag I was cold but surprised to see that I wasn't drenched in sweat. The inside of the AMK bivy felt dry as a bone.

Once out of the bathroom I went to my regular bed. I was curious to see how much condensation there might have been down at my feet. This morning I pulled the bag in from the cold and felt the bag for stiffness or ice. Nothing. There was also no build up in the foot of the bivy or sleeping bag that I could detect.

Results? I couldn't be happier! I was as comfortable as one can be in a bivy at temperatures below -20 C and could still get stuff done without having to be completely zipped in. I'm not sure just how much cooler I could go but there are always other things you can do like stuffing clothes into the bag(s) or covering up with a jacket (I did neither for this test), etc.

For me this proves the worth of a modular system (either home brewed like mine or a purpose built system) and of a vapor barrier. The next test will have to be a practical test in the real outdoors but I don't think this will be an issue knowing what I know now. I think the real test will be in the spring when weather is very unpredictable and the different layers will need to be shed in differing combinations to prevent overheating.

And to think the whole thing cost a fraction of what some pay for less functionality.

I have one picture. I'll post it later today.

GREAT!!!--just what i like to see/read..really trying out
the gear..you can make as many lists as you like and buy
stuff by the BOB full but untill you've tryed to light a fire
with it--or ate it--or slept out overnite in it all you have
is a inert gizmo..i know that some of us don't want to used
up an expensive bit of gear by trying it out,but i would
like to see more posts like this--

Terrific Test and Post Hacksaw, Thanks.

I went back and checked out your sleeping system post again to find out what it consisted of, the size (big as a watermelon) and weight (5.5lbs); all of which is impressive considering the temperature it was used at (-23*c).

I do not know if I could tolerate sleeping under just a bivy bag during a rainstorm, I think I would feel very exposed and how do you keep the rain off your face? I have no exposure to sleeping in a bivy bag other than the Canadian Military Gore-tex version during the winter but that was within a winter tent.

What is a bivy bag like to use during a thunderstorm?

Mike

Just this week I bought the same bivy also to use as a vbl. I am hoping to get out camping in late February to give my system a shake down spin. I have a army surplus gore tex bivy sack that I bought via ebay for under $50. To date I've not had any condensation in the bivy, but have yet to use it in the winter conditions.

I bought the emergency bivy instead of the thermo-lite bivy. What's the difference?

Basically my system will be the same as yours. Down bag, vbl, thermarest (and possibly a foam pad) and a gore tex bivy sack.

SwampDonkey: Those who don't like tight enclosed spaces need not apply. The is a bit of room but not much. I can get my arms up and out and that's about it.

Many bivy's have something covering your head to protect it from rain and whatnot. Some of these even have what's like a mini tent around your head complete with poles. They are also heavier...they are also more expensive (much more in some cases).

This bivy is not protected from rain where the mesh is (though it does have creative little gutters to keep rain from running up and in at the head). You can either throw something waterproof over your head at night (like a jacket) or sleep under a shelter (anything from a tarp to a tree).


justmeagain: There are a few differences (maybe more). One, the emergency bivy is much smaller/lighter. I think it's just made from more or less standard space blanket materials. The material in the thermo-lite is heavier, has a fuzzy lining (80% radiant heat reflected instead of 90% with the emergency bivy), is sewn all the way around and where it's not there's velcro...and it has a closable mesh foot vent. Plus the Thermolite is designed to be reused...not just for emergencies necessarily (AMK suggests is as standard equipment for ultralighters)

Thanks for the reply Hacksaw.

I do not think the tight enclosed space would bother me but was thinking I would feel very exposed to the elements if it rained.

I recieved a Hennesy Hammock (Expedition ASYM with Hex Fly deal) for Christmas but have not tried it yet (too cold), it will be my first adventure outside of a normal tent/tarp/shelter.

Mike

I haven't taken mine out of the package yet. I hope it's reusable, but if not I'll buy the other bivy next time. At least it's cheap enough to experiment with. At the time I bought mine I had intended to buy Western Mountaineering's vbl, but the store was out of stock. The adventure medical is a fraction of the cost and may work equally as well for my needs.

Very cool. When I upgrade my sleep system, I'll probably pick a Thermolite as an inner bag.

Your point about needing to urinate while inside a sleeping bag is not lost on me. I rarely need to get up at home, but while camping I need to relieve myself every night. Nothing worse than having to get out of a bag in the cold.

Awesome test. I have done my own bag tests on the patio.

You successfully took a bag well below it's rating with your system.

I do have the amk Thermolite 2 bivy, but I have never used it. I have never thought to use it the way you did.

You mentioned in the other post that you use it as a "vapor barrier". Can you please explain what that means with an example?

Thanks.