During the first part of her life, Hercules was an ocean tugboat. In 1947, the Hercules and the tug Monarch were tasked with towing the hull of the battleship Oklahoma to San Francisco Bay for scrapping. The Hercules was unable to break free until the last moment, narrowly avoiding being dragged to the bottom of the sea by the Oklahoma.
In 1986 she was designated a National Historic Monument. She is now one of the San Francisco Maritime National Historical Park exhibits and is moored at the Hyde Street Pier.