[Satrek2000]

I think there might be a smaller type without a cargo hold (or just a small one) which you can peg somewhere near the beach, just as a private ferry. Only the owner can enter whenever he wants, others can only get aboard when the owner opens the gate, and only he can controle it. There should be special areas where you can peg it, to keep the beach from getting overcrowded (say near towns). These boats decay at some rate, so you have to repair them, but that shouldn't be a problem as you can keep boards in the cargo hold. There also should be the possibility to get off the boat whenever it's pegged somewhere, not limiting it to docks - hence allowing players to enter an island from where they are not expected...