The O’Brien is approved by the American Bureau of Shipping, certified by the U.S. Coast Guard, and fully seaworthy — the only active Liberty Ship in original configuration. Operated as the National Liberty Ship Memorial, she is moored at Pier 45, Fisherman’s Wharf and open to the public most days. Virtually the entire ship from engine room to flying bridge can be seen by visitors. Boilers are “lit off,” and the 2500-horsepower, triple-expansion reciprocating steam main engine is operated on Steaming Weekends (normally the third Saturday and Sunday of each month) so visitors can see the engine plant in action.