All I do is fish. And sorry I didn't clarify, it's an island floating dock out towards the middle. Not a dock attached to his shore. I was basically fishing the middle.
Have you asked your neighbor to move his floating dock closer to his shoreline?
Another idea: When my kids are fighting, I use duct tape. I stick a line of duct tape from one side of a room to the other and tell them they are not allowed to cross the line into the other's territory. Although admittedly duct tape would not work well on a pond, could you come to an agreement with your neighbor on who gets what half of the pond for their own personal use, essentially drawing a line down the middle of the pond?
Answering justalayman's questions, by the way, might help you get something closer to a legal answer.