A snow saw is useful for building snow shelters and for avalanche danger testing. Some models are said to be easily attached to ski/trek poles in order to increase the handle length. Under what circumstances would I wish to extend the handle length of a snow saw? I read at a forum that an extension would allow cutting a cornice but don't understand when it would be wise to do so. Maybe you know why a cornice should be cut or you know of another use for a saw could do with a much longer handle.
The main reason that I found is for cutting a cornice, sometimes referred to as the bombs of the backcountry.
Extending the handle allows one to cut it without being too close, and as for why one would want to cut a cornice,
The advantage of cutting cornices is that it allows backcountry skiers or mountaineers to test a slope without getting onto the slope and putting themselves at risk. It’s also superior than using results from stability tests performed on adjacent slopes. That all seems straight forward, but make no mistake, cutting cornices can be very dangerous.
“The most obvious danger associated with cutting cornices,” says Ron Johnson of the Gallatin National Forest Avalanche Center, “is being too close to the edge and falling off the ridge when the cornice breaks.”
Also see video here
Basically, it would give you an idea of how stable the slope is, because if a 1200 lb piece of cornice doesn't trigger an avalanche, not much will.
Another reason for extending a snow saw handle is for preparing a snow stability test, for avalanche awareness. There are various such tests and most initially require digging a trench then isolating a column of snow. The back side of the snow column (opposite the trench face) can be isolated in one of three ways:
Place vertical poles at the back corners. Thread a cord with knots from the front of the trench, around the poles, and again to the front. Pull the cord back and forth and downwards, effecting a saw action.
If you've no cord or if the cord saw cannot go through a layer of ice: Extend a saw via a pole and cut the back snow column with it.
If you've only got a shovel: Cut a shovel width space around all sides the column. (This might be difficult to do without disturbing the column.)
Expanding on cutting cornices, here's a video clip of ski guide Theo Meiners using an extended snow saw to drop a cornice. Note that most everything happening in that video is intentional (if dangerous, should things go wrong). There are other techniques; this is just one possibility. The general procedure of what's going on in the video is:
- Cut a triangular notch in the cornice, this will be your exit hole. Notice the general shape in front and right of Theo.
- Cut along the length of the cornice. This will make the cornice begin to fracture on a predictable line, as opposed to just trying to stomp on the cornice at a lucky place.
- With your tips pointing at your exit hole, stomp on the cornice with one foot--don't lose your balance when it goes! As soon as the cornice starts to break, dive through your exit hole and keep carrying speed across the slope away from the cornice.
Discussing the why's and when's of this technique is beyond the scope of an answer. Seriously, being near a cornice is a great way to get killed. The takeaway is that you can "safely" drop cornices that would be too large to just stomp with a ski, and do it much more quickly and with less gear than carrying a dedicated cord/cable.
That being said, the primary benefit of being able to attach a snow saw to a ski pole or probe is to make cutting the back of a column easier in a snow pit (RB and ECT in particular), particularly if there are stiff layers / crusts in your snow profile.