Who improved the steamboat?

John Fitch constructed four different steamboats between 1785 and 1796 that successfully plied rivers and lakes and demonstrated, in part, the feasibility of using steam for water locomotion. His models utilized various combinations of propulsive force, including ranked paddles (patterned after Indian war canoes), paddle wheels, and screw propellers. While his boats were mechanically successful, Fitch failed to pay sufficient attention to construction and operating costs and was unable to justify the economic benefits of steam navigation. Robert Fulton (1765-1815) built his first boat after Fitch's death, and it was Fulton who became known as the "father of steam navigation."

* http://inventors.about.com/library/inventors/blsteamship.htm