The third USS Grampus, a 352-ton stern-wheel gunboat armed with two brass 12-pounders, was originally CSS Grampus, scuttled by the Confederates on 7 April 1862 to prevent her capture. However, the Union Gunboat Flotilla raised her during May 1862, and she is believed to be the Grampus No. 2 that burned the following 11 January.
The fifth USS Grampus, originally Boothbay, was 1708 tons and 126 feet long, built by Neafie and Levy, of Philadelphia, Pennsylvania. She was purchased from the Eastern Steamship Line of Boston, Massachusetts and commissioned 14 December 1917, at the Boston Navy Yard. Her name was changed to Grampus in November 1920. She was assigned to ferry service between the Washington Navy Yard, Indian Head, Maryland, and Dahlgren, Virginia. Grampus decommissioned 11 December 1930. Her name was struck from the Naval Vessel Register on 30 December 1930, and she was later sold to the Buxton Line of Norfolk, Virginia.