Charleston 's propulsion system is unknown .
Her engine had a diameter of 36 inches ( 910 mm ) and her propeller was 8 feet 6 inches ( 2.6 m ) in diameter .
Charleston 's propulsion system is unknown , but her engine had a diameter of 36 inches ( 910 mm ) and her propeller was 8 feet 6 inches ( 2.6 m ) in diameter .