Clarify for sure
BoatUS mag recently had an article on this. Best I can remember, the main difference is whether the boat is in immediate danger to itself or other boats and or if its "hard aground." Seemed to me there was a lot of room for interpretation. If you are towed you are charged a fee, if salvaged the salvaging company can claim a significant percentage of the value of your boat, the theory being that the boat would have been lost otherwise. There are a number of factors involved in this determination.The magazine suggested that you clarify that it is a tow before you get the tow. As a lawyer I recommend that you either have paper signed clarifying the situation and the charge, or at least you have as many witnesses as possible.