So an interesting this I discovered today when trying to plow off 3" of snow: If the edges are thin from a recent thaw while the center is still 6" plus. If I get a crack near the edge which pushes down on the water below, I wind up making a wake/wave out in front of the plow. The added weight of the snow makes it even larger! I managed to break up 6" ice this way all across the pond and ruined the skating rink. I had to abandon ship for fear of going down in a corner of one of the sheets. :-(.
Lesson? Stay away from the edges and try not to make the rink so darned large.
