USS Water Witch (1845)

USS Water Witch (1845) was a steamer designed and constructed by the U.S. Navy with an experimental propulsion system that never quite worked, the Hunter wheel.

The first Water Witch, a steamer built in 1844 and 1845 at the Washington Navy Yard, saw little active service. She was originally constructed to serve as a water supply vessel for the Norfolk, Virginia, station, but she was not used for that purpose because her draft was too deep for her to pass through the locks of the Dismal Swamp Canal to obtain fresh water. Consequently, she was fitted as a harbor vessel and tug.

Water Witch used to test the Hunter Wheel
However, her unique, but poorly conceived, Hunter Wheel propulsion system caused her to fail in that mission as well. In order to rid steamers of their vulnerable above-water paddle wheel housings and to increase their broadside weight, Lt. W. W. Hunter had devised and patented a system of placing the wheels inside the hull of the ship at a right angle to the keel making their rotations horizontal rather than vertical. The paddles extended their full length outside of the hull for maximum contact with the water for propulsive purposes; and, inside the hull, they were encased by a cofferdam which kept the water from entering the ship proper. Unfortunately for Lt. Hunter, the wheels lost much of their power pushing water through the encased area inside the hull, forfeiting between 50 and 70 percent of their potential power.

Termination of test and conversion to service as a “new” ship
That fact was recognized before the ship had served a year, so she was condemned and sent to Philadelphia, Pennsylvania, where she had arrived sometime before 21 November 1845. Her modifications there were so extensive that, in spite of the fact that she retained her name, the new creation is regarded as a second, distinct ship—USS Water Witch (1847).