USS Harkness (AMCU-12/YMS-242) was a YMS-1-class minesweeper of the YMS-135 subclass acquired by the U.S. Navy for the task of removing mines that had been placed in the water to prevent ships from passing.

Following the conquest of the Mariannas, she returned to Pearl Harbor 25 December before sailing to the U.S. West Coast for conversion to a surveying ship.

She sailed 29 March for the U.S. East Coast; touched at Acapulco, Mexico, Guantanamo Bay, Cuba, and Norfolk, Virginia; and arrived New York 8 May.

Assigned to the Atlantic Fleet Mine Force, she departed New York 2 July 1952 and arrived Norfolk, Virginia, the next day.

Reclassified MHC-12 on 1 February 1955, she continued her part in numerous mine clearing exercises, in July 1957 even operating in Cuban waters out of Guantánamo Bay and Havana, Cuba.