Sleeping and Sliding on Snow

[Patrick McFarlane]

We’re supposed to get a 0F night next week and I want to use the opportunity to test out a Borah Gear Snowyside eVent bivy that I recently acquired second hand.  I will be pairing it with a neoair Xtherm sleeping pad, 0 deg F UGQ renegade quilt, separate MYOG Apex 15 (2 layers 7.5oz) hood, vapor barrier suit, and lightweight down jacket and pants.  I also plan to use a SOL space blanket as a groundsheet under the bivy.

Since my backyard has a bit of a slope to it (maybe 10 degrees), I’m a bit concerned about how to avoid sliding downhill all night, especially because the bivy has a slippery silpoly bottom and will be sitting on packed snow.

My plan so far is as follows:

1. Lie across the slope and use snow to form a more or less level shelf
2. Make a lip on the downhill side of the shelf that would prevent sliding off it

Thoughts?  I would appreciate any tips from people that have experience camping on snow, and especially in dealing with a slope.

[BlackHatGuy]

While I have slept on snow, I haven’t done it on a slope. But I’d think you could just dig into the snow a nice shallow trench that is deeper than you pad and bivy, but sized for just you and your sleeping stuff, and that should keep you in place.

[Patrick McFarlane]

While I have slept on snow, I haven’t done it on a slope. But I’d think you could just dig into the snow a nice shallow trench that is deeper than you pad and bivy, but sized for just you and your sleeping stuff, and that should keep you in place.

 

That sounds like a good idea. Not sure if I should cut the trench across the slope or with it.  Going with the slope would be easier because I wouldn’t have to worry as much about levelling it out…just point my feet downhill.

I’m really wishing now that I had a 1/4″ thick eva foam mat…seems like the perfect way to create grip between the snow and my bivy.  No way that I’ll be able to order one in time though.

[David Thomas]

I think either plan works.  If it wasn’t your backyard and there was any loose snow on the surface, I’d try to be in the lee of some trees.  It would be a pity for a wind to come up and move loose snow unto you all night.

When you carve out that shelf, remember to scoop out an extra 1-2 inches of depth for your hips and leave 4-6 inches as a pillow.

[David Thomas]

And consider what’s overhead.  If you’re under a roof or canopy of trees, you won’t get much net radiant cooling.  But on a clear calm night, the top of your sleeping bag could get 10F or more below ambient.  That is both a temp differential your sleeping bag rating has to handle and it can cause frost to form on the top of your sleeping bag.  If it stays there all night and you shake it off in the morning, that’s not so bad, but if it melts into your bag, that’s not good.

[Patrick McFarlane]

…it can cause frost to form on the top of your sleeping bag.  If it stays there all night and you shake it off in the morning, that’s not so bad, but if it melts into your bag, that’s not good.

I think my vapor barrier suit should take care of frost issues right?

But on a clear calm night, the top of your sleeping bag could get 10F or more below ambient.

Is that an argument for using a tarp overhead?

[Patrick McFarlane]

Update.  So I spent the night outside on Monday evening.  Temperatures got down to 3 deg F and it was a fairly clear night.

The trench idea worked well.  I didn’t slide at all and I actually made it a bit wider than my bivy.  I think the small amount of heat passing through my sleeping pad molded the surface of the snow a bit and helped to prevent sliding.  I also didn’t pack the area down really firmly…just walked over the surface a few times.  I imagine this probably left more opportunity for the snow to conform underneath me.

Also not a trace of frost except in a small area near the bivy opening, which I think was caused by moisture in my breath.  The VB suit is definitely the way to go…with no evaporation of insensible perspiration, there’s no moisture to form frost.

Overall, it was super comfortable.  Sleeping on a good sized snowpack rivals a bed IMHO.

[Author]

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