John Hancock was launched by Boston Navy Yard on 26 October 1850 for service as a steam tug and water tank in that yard. However, she was soon manned by a temporary crew and dispatched to New Bedford, Massachusetts, to aid in quelling riots. When order had been restored, she returned to Boston, where she served until summer 1851 when she steamed to Annapolis, Maryland, for duty as a practice ship at the United States Naval Academy. At the end of the summer's midshipmen cruises, she sailed to New York, where she commissioned 6 September 1851, Lieutenant J. W. Livingston in command.