Where does a Yacht become a ship?

[charmc]

Originally Posted by Landlubber

You can put a yacht on a ship, but you cannot (or should not) put a ship on a yacht.

[PI Design]

Originally Posted by kach22i

Is there a submariner's version?

A boat takes one torpedo to sink, a ship takes at least two?

Aren't all submarines boats even if over 400 feet long?

All subs are boats, and all ships are targets.