He was commissioned lieutenant on September 8, 1841 and commanded the steamer Water Witch in the U.S.Navy's Home Squadron from 1848 to 1849, served again on U.S. Coast Survey duty from 1851 to 1857, and cruised in the steam frigate Merrimack on special service from 1857 to 1860.

Commended by Farragut for his actions, Wainwright later participated in the squadron's operations below Vicksburg, Mississippi, until taken ill with fever.

[5] On March 1, 1849, Wainwright married Sarah "Sally" Franklin Bache (1824–1880) in Philadelphia, Pennsylvania.

Her maternal grandparents were Arabella Maria Smith and Alexander J. Dallas, an American statesman who served as the United States Secretary of the Treasury under President James Madison.

Together, they were the parents of: Wainwright died at Donaldsonville, Louisiana, on August 10, 1862, aboard USS Hartford.