IT’S a skier, boarder or hiker’s worst nightmare – the cold, harsh reality that you unwillingly have to spend a night out in the backcountry.
You simply have no idea where you are, have exhausted all your options, and night is drawing in very fast. With darkness comes cruel weather, temperatures of minus 15°C and much lower – not factoring in wind-chill. In these conditions, hypothermia can hijack your body in a matter of minutes. In light of all this, you need to hunker down and wait out the night in the warmest, safest location possible until the sun rises. Then, you can reassess your options, or wait until someone finds you. In many cases, the best place to spend the night is in a snow cave…
Readers may recall that in the last edition Powderlife we brought you tips from Black Diamond Tours tour guide and certified Canadian Avalanche Association guide, Andrew Spragg, on how to survive being lost in the backcountry. This edition, Andrew takes you step-by-step through how to build something that may just save your life – a snow cave.
Step 1: In order to dig a snow cave, you need to find a sufficiently deep pocket of snow. Use your avalanche probe to find a suitably deep location, hopefully with at least three metres of snow pack depth. Adequate snow depth, free of rocks and ice, is needed. Look around trees and on leeward slopes if the snow pack is shallow. In Hokkaido, this will generally not be a problem much past mid-December, thanks to heavy snowfalls.
Step 2: Once you have found a suitably deep location, dig a hole straight down at least three meters deep. Try to avoid sweating while working by shedding layers of clothes. Use a shovel to dig the snow cave – something that you should always carry with you out in the backcountry (an ice axe may also come in handy). Digging by hand should be for emergencies only. Following this, dig an entrance into the side of your hole. If you are on a slope, the entrance would go on the uphill side. Keep the entrance at the very bottom of the hole and as small as possible, then tunnel into the slope.
Step 3: Once you have dug inwards about 50cm, you can begin to dig upwards and sideways, opening up an area to sleep in. Make sure it is big enough to accommodate everyone, but not so big that it is harder to stay warm. The roof should be in a dome shape to prevent dripping on the occupants. The idea is that you will actually sit/sleep above the height of the entrance, so that your body heat will be trapped inside the cave and not get sucked out the door. Remember that over the course of the night your cave will settle and sag lower, so make sure that the roof is sufficiently high to allow for this.
Step 4: Once you have cleared a sufficient sleeping area above the height of the door, you need to prepare a bed or sitting area for yourself. You need to try to get yourself off of the snow so you don’t lose valuable body heat, or get wet. If there are trees nearby, you can use tree boughs or branches to form a sleeping surface. Otherwise, use your pack and anything else that you can think of to sit/lay down on that keeps you off of the snow.
Step 5: Next, light candles (if you have some, they are a good idea) inside the cave. This will help the inside of the cave to develop an ice layer to become stronger, as well as providing valuable heat that should remain trapped inside the cave.
Step 6: After this, head back outside and poke a few air holes through the roof of the cave with your probe before going back inside.
Step 7: Use the remainder of your gear to plug the entrance hole of the cave to trap all possible heat inside. The entrance may be partially blocked with chunks of snow to block wind and retain heat, although it is vital to prevent drifting snow from completely plugging the rest of the entrance in order to maintain a constant air supply.
Step 8: While waiting out the night in your snow cave, here are a few tips on how to stay safe and warm:
* Stay dry – avoid sweating and keep yourself off of the snow as much as possible. Always stay one step ahead of your body temperature. If you’re about to work hard, take a layer off to avoid sweating. Conversely, as soon as you stop working hard, re-layer again. It’s much easier to stay warm than get warm.
* Insulate yourself with anything and everything you can: backpacks, tree branches, space blankets, all available clothing. If things are really bad, focus on keeping your core warm and ignore your extremities.
* Keep moving. Swing your arms, jump up and down, hit yourself… whatever it takes to keep the blood flowing.
* Urinate frequently. Your body expends a surprising amount of heat energy keeping the fluids in your bladder warm. Since this is waste product, and no longer much use to you, there’s no point wasting heat energy keeping it warm.
* Keep yourself well-fed and hydrated if possible. Staying warm requires your body to burn energy, so the more available energy you have, the warmer you will stay.
Why are snow caves warm?
ALTHOUGH it is made entirely of snow and ice, a snow cave has thermal properties similar to an igloo (as used by Eskimos), and is particularly effective at providing protection from wind and low temperatures. This is due to snow’s excellent insulation properties. A properly made snow cave can be 0°C or warmer inside, even when outside temperatures are -40°C.