The definition I always used was, you can put a boat on a ship but you can’t put a ship on a boat, so when I tie my dingy to the deck, it meets those criteria too. Officially, there is no specific definition. Ship owner do tend to get more irritated by people calling their ship a boat than boaters do when you call their boat a ship. Then we get into the definition of what’s a yacht and what’s just a boat. That’s a whole different rabbit hole.

Webster defines a yacht as a small saint boat with living space below deck. However in the cruising world, a yacht under 50’ is just a boat…

Ultimately, whatever the captain says is law. I go through these with every souls that sails with me. If they have a problem with any of these, they stay on the dock!