Boat, Ship, Vessel
Your boat has fins and a mouth! It's still a boat though.
Picture this boat. It's still a boat, but there is a big mouth on the front and it has fins that it paddles forward with.
せん
ふね
None
This boat belongs to the centaurs (せん). That's probably why you've never seen a boat like it before.
Picture this mouth and boat with a bunch of centaurs riding in it. Centaurs have a lot more parts than humans, so it makes sense that their boats have more parts (animal ones) too.