I came across your question while I was searching the net for the same thing. Have you found anything ?
I'm guessing it's a boat with a flat bottom.
Perhaps you are referring to a hydrofoil.
I am no professional, but I'd say that when it comes to the term 'floating' it does not matter. However, flat would mean that there is less water displacement, therefore more molecules floating.When...
Either Robert Fulton or Henry Shreve, but I'm going off of a worksheet for History...