Brings to mind a question, Glojo. A number of fine Naval personnel have tried to explain the difference to me. Two I remember are:
A ship has more than one deck above the waterline. (I think it was one.)
When a boat turns to port, it heels to port. When a ship turns to port, it heels to starboard. (Probably because of all the decks above the waterline.)
Would they be right?