I would like to say, the boats are most fun form of transportation I have used in DayZ since the alpha. They fit the game really well, are simple and allow people to traverse waters quite nicely. As I understand, the boats have decay meaning if the boat engine is ruined it will eventually respawn somewhere. This is a fantastic mechanic since dead engine boats don't really server no purpose and more fresh boat allows for more fun for other people looking for them on the coast.
I would suggest extending the decay to other forms of vehicles as well such as cars and trucks. Consider adding these cases of decay timer for cars and truck: when the engine is ruined, when there are no wheels on the car, when there are only ruined wheels on the car.