Punching into crevasses: skis vs on foot

Trying to garner some more information on something that's always gnawed at me. Are you truly less likely to punch through into a crevasse or bust a snowbridge while on skis as opposed to on foot? It seems that I and many others have at least the superstition that being on skis will minimize your PSI on the snow and thus your chances of falling into something. But can this be in any way verified? Anyone have a first hand experience with having crossed something safely on skis that failed for persons nearby when on foot and shortly thereafter? Any authorative information out there about this subject?<br>To play devils advocate for my own superstition: if whatever you're about to fall into will fail the width of an entire ski, seems like being on skis wouldn't have helped. And, if you happen to weight a strong turn on top of a failure point, the PSI might even be higher while skiing. Thoughts?<br>This brought to my mind by the Inter rescue of last weekend. In most cases I've heard of people falling considerable distances into an Inter crevasse, they were glissading at the time. Having your eyes less than 3 feet above the snow surface cuz you're sliding down fast on your butt with snow flying from your feet and limiting visibility - a factor? I've glissaded right into small bergschrunds because of this in the past, before I more or less gave up sitting glissading for other safer pursuits.

If the crevasse opening under the snow bridge is less than the length of a ski, clearly skis keep some of your weight off the crevasse. This certainly reduces the risk by some finite factor, which I won't attempt to estimate.<br><br>Weighting a turn may create more pressure, but that will be because of your speed. Your speed limits your time over the snow bridge. <br><br>Let's assume you travel at 10 m/s (~22 miles/hr, a very reasonable skiing speed). If you are above a crevasse opening below a snow bridge that is 2m wide, this gives you about .2 seconds above the abyss. In .2 seconds, gravitational freefall is only (1/2)*9.8(m/s^2)*(.2^2)~1meter. <br><br>The same analysis for 15 m/s (~33mph) results in a fall of less than 1/2 meter, in which case your speed would certainly carry you over the crevasse, albeit leaving you in a tumble. <br><br>Thus my answer is: skis certainly are safer. The bridge isn't likely to collapse until you are somewhere near its center, so you might be able to add a factor of 2 into the equation, meaning you only would have fallen less than a foot on the 2m bridge skiing 22mph. I think skis help a great deal. <br><br>This analysis also suggests the safety conscious should ski fast!<br>

That's a good analytical spin Sky. <br><br>Here's an irrational desk jockey's conglomerated jumble of misguided assumptions for a measured look at the opposite spectrum of reality - opinion. Often people question my use of climbing unroped. One should note, though, that it's not the climbing that concerns me, but the descent. If I had to plunge step down a glacier I would without a doubt be wearing a rope, but with skis chosen as my weapon of choice, the maneuverability and speed opt for less risk in my opinion. Of course that assumes that one doesn't ski into a crevasse due to unchecked enthusiasm As for skinning, I used to believe that was safe also until I fell in a crevasse, so I am less willing to assume that one shouldn't be roped while skinning up a glacier, especially in winter while climbing on wind deposits which are notorious for covering up and smoothing out a(n) otherwise giant gaper(s). But back to your original question, is skiing unroped safe? To answer lets first look at the alternatives:<br><br>1. Ski roped<br>2. Downclimb roped<br><br>If you ski roped are you placing pro? If not, how much safety does the rope offer? With skiing, I think it just gets in the way and puts too much dependence in the hands of your partners, more so than climbing because it&#8217;s easier to make a mistake skiing because the rope can get in the way of both your attention and skis. I think this is something that the sport may have to mature too or accept as a necessary risk. I don&#8217;t know. In a way it is a deterrence for lesser skilled individuals, where as a rope can work as a crutch to justify lesser skilled individuals to venture where they may not be ready too. Of course this applies even more to steeps, but that&#8217;s a whole other bucket of worms. I do plan on using a rope more on steeps but only to lessen risks at certain cruxes, not to ski an entire route roped. <br><br>As for downclimbing roped. I love to ski and this is part of the experience. If I&#8217;m going climbing and there is snow you can expect my skis will be on my back. <br>

The fact that you are less likely to punch through into a crevasse with skis on is evident/displayed even off of glaciers. Verification comes when the snow starts melting in June and lower elevations expose creeks, rock, stumps and downed trees with many bridges, moats and holes. (although possibly on a smaller scale) When skinning (slow) and/or skiing (fast) at any temperature and in any snow condition, you can test this; (I have many of times and you should too, especially if your superstitious) skier moves across, hiker behind, punches in to his armpits (just introduce someone to the sport and have them hike up behind you! They'll love it.)......As for gaping crevasses? Scout them out (photos,recon,TR's), wear the skis going up (if possible), assume the risk, and be prepared to extricate. I think you are truly less likely and this IS AUTHORITIVE INFORMATION. (Note: any of the above may be wrong on the day you go ski) Now, call the Witch Doctor. 555-WHAT.

I agree fully with Toby. Anyone who doesn't feel more vulnerable on foot than on skis need only experiment a bit with thinly-bridged streams. First, walk across on skis: feels safe, solid, and secure, right? Now take off your skis and boot across the same bridge. Don't forget to bring a dry pair of socks.

Hmm. I like Sky's analysis. I've never thought of the perspective that every moment you spend on top of something suspect is actually a moment of suspended free fall, so maybe you oughta minimize it. (Sometimes that's a good tactic when scrambling talus and choss, too.) I'm not sure that stream undercut bridges and crevasse bridges equate 100%, crevasse bridges have a lot of other factors at work. They aren't melting out nearly as much from below; in many cases they start to fail naturally because the snow bridge is actually being stretched out too far laterally, rather than being ablated and thinned. In that case it's a system under tension, where any piece of the system might fail under your weight and not necessarily the very thinnest part. Also, crevasse bridges tend to have a bunch of odd intermediate layers where you might only partially fail it.