It doesn't matter if you are trolling or just heading out into the lake, they will cast it at you regardless. These guys doing it are morons. When I was there recently we had the same thing and we were just heading out to the lake. Not even trolling. One hit our boat, next time we went past I had a bulldawg on and as soon as one landed about two feet away I casted over hos line and snagged his lure. In the end he had to cut his line or I was going to have a new combo along with my new bulldawg.
As Brian said it is just a couple of them doing it and that was the case for us to.
Green Canada you really are annoying.