In ancient times
The profession of the ferryman is embodied in Greek mythology in Charon, the boatman who transported souls across the River Styx to the Underworld.
Speculation that a pair of oxen propelled a ship having a water wheel can be found in 4th century Roman literature “Anonymus De Rebus Bellicis”. Though impractical, there is no reason why it could not work and such a ferry, modified by using horses, was used in Lake Champlain in 19th century America. See “When Horses Walked on Water: Horse-Powered Ferries in Nineteenth-Century America" (Smithsonian Institution Press; Kevin Crisman, co-authored with Arthur Cohn, Executive Director of the Lake Champlain Maritime Museum).
http://en.wikipedia.org/wiki/Ferry#History