1) Ark 2) Barge 3) Dredger 4) Houseboat 5) Hoy 6) Pontoon 7) Wherry 1) Barge 2) Boat 3) Boat type 4) Canal transport 5) Fur trade 6) Lighter 7) River transport 8) Shallow-water transport 
A flatboat is a rectangular flat-bottomed boat with (mostly) square ends used to transport freight and passengers on inland waterways. The flatboat could be any size, but essentially it is large, sturdy tub with a hull that displaces water and so floats in the water. This differentiates the flatboat from the raft, which floats on the water. A flat...
• (n.) A boat with a flat bottom and square ends; -- used for the transportation of bulky freight, especially in shallow waters.
Flat'boat` noun A boat with a flat bottom and square ends; -- used for the transportation of bulky freight, especially in shallow waters. 
a large, flat-bottomed boat for use in shallow water, esp. on rivers.