The world's oldest commissioned U.S. warship, the USS Constitution, sails under her own power for the second time in 131 years Sunday off Boston. The brief sail -- 17 minutes at a top speed of 3.1 knots, powered by four of her 36 sails for just over 1,000 yards -- commemorated the 200th anniversary of the Constitution's victory over the British frigate Guerriere during the War of 1812.