It’s finally getting into real winter conditions here in Minnesota, but that still doesn’t mean it’s winter as normal.
Sunday’s snowfall led to three snowmobile crashes on lakes where drivers went through thin ice or open water. In one case, the snowmobile driver died. According to the press accounts, many snowmobile drivers like to “skip” their machines over open water. It got me wondering how this actually works.
It’s actually much like how a stone that is thrown at the right angle and speed skips across open water. Checking the web for snowmobile sites, I found out the specific details.
The snowmobile skip formula works this way: In order to skip, the snowmobile must be going at least 5 mph for every 150 lbs. of vehicle (or fraction thereof). For example, if a snowmobile and rider weighed 780 lbs., it would have to be going at least 30 mph to skip. The distance of water a snowmobile can cross is 2", plus 1/2" for every 5 mph over the minimum skip-speed. If the above-mentioned snowmobile was going 45 mph, it could cross 3 1/2" of water; at 75 mph, it could cross 6 1/2" of open water. There’s also friction, or drag, involved in this formula. A snowmobile decelerates 5 mph for every inch (or fraction) of water it "skips." The snowmobile above, crossing 6-1/2" inches of water at 75 mph, would be going only 40 mph when it got to the other side.
A snowmobile cannot change direction while "skipping" -- it can only go in a straight line. If a snowmobile doesn't make it across the open water, it sinks. It only takes one second for a snowmobile to sink to the bottom of a lake or river.
So, as they say on all the stunt shows, don’t try this at home….or on a lake near your home. Across the U.S. and Canada each winter about 50 people die from snowmobiles crashing and sinking into frigid waters.
Interestingly, a graduate from the University of Minnesota is developing a way to minimize the deaths of snowmobilers falling through the ice. John Weinel is now working with university students to come up with an automatic floatation device that could deploy from a snowmobile, much like an airbag in a car, when a snowmobile crashes into water. That work has already led to floatation equipment law enforcement officers can use at the scene a snowmobile water crash to help keep victims at the surface until better equipped rescuers can get to the scene.
Of course, the best thing to do if you're driving a snowmobile is to avoid driving it anywhere there is a chance to be open or thin ice. You and your snowmobile will be able to get around better and happier if you never go sinking into chilly water.