This has happened 3 times before in my 1.7.4 survival server. I will be riding in a boat going towards some land. When I get out of the boat it will drop me about 20 blocks behind me, on my boats previous trajectory. The boat will apear where I got off it on the shore. When I try to destroy it, it won't break, and I can stand on it like it is a solid block. When I go back to where I was dropped off and I randomly hit around that area, 1/3 times I hit a boat, which is invisable. When I break it I get my boat back and the invincible one dissapears. This is a really anoying bug.