1919. She then underwent an overhaul at Norfolk. Service at San Francisco Dreadnaught left Norfolk on 23 January 1920 bound for the Mare Island Navy Yard in Vallejo, California, where she arrived on 15 March 1920 and began another overhaul. When the U.S. Navy adopted its modern hull number system on 17 July 1920, Dreadnaught was classified as a "harbor tug" and redesignated YT-34. She was assigned to the 12th Naval District for duty in the San Francisco area. On 14 March 1922, Dreadnaught was decommissioned, but she continued her 12th Naval District duties in the San Francisco area for many years after that in a non-commissioned "in-service" status. Dreadnaught was reclassified as a "gate tender (non-self propelled)" - an anti-submarine barrier gate craft - and redesignated YNG-21 on 7 October 1940. Disposal In September 1944, Dreadnaught was stricken from the Navy List. She reportedly was destroyed sometime thereafter. References Department of the Navy Naval History and Heritage Command Online Library of Selected Images: Civilian Ships: Dreadnaught (American Tug, 1917). Served as USS Dreadnaught (ID # 1951, later YT-34 and YNG-21) in 1918-1944. NavSource Online: Section Patrol Craft Photo Archive YNG-21 ex-YT-34 ex-Dreadnaught (ID 1951) Auxiliary ships of the United States Navy World War I auxiliary ships of the United States World War II auxiliary ships of the United States Tugs of the United States Navy Ships built in San Francisco 1917 ships