Recently saw a large piece of material stitched on to the sail cover of a boat (near Have Fun's boat, I think, in Mosmon) which said, "OWNER: 04########". Actually, it said his actual phone number. That seemed like a great idea. That way a courteous boater might easily call you if there was something that needed attending. I've called the Maritime Boat Safety Officer a few times with listing boats, moored boats colliding in near zero tides, etc. I'd like to know ASAP if something was wrong.

Do you see any down sides to this besides the possibility of prank calls?

I wonder maybe there wouldn't be that many prank calls
Anyway think of the upside, you can just say to to your wife/boss or other significant person that already thinks you spend too much time on your boat:
"I don't want to go but I have to the boat is sinking"