[Floyd]

http://en.wikipedia.org/wiki/Mark_14_torpedo

Dan Daspit (in Tinosa) carefully documented his efforts to sink 19,000 ton whale factory ship Tonan Maru III on 24 July 1943. He fired four torpedoes from 4,000 yd (3,700 m); two hit, stopping the target dead in the water. Daspit immediately fired another two; these hit as well. With no enemy anti-submarine combatants in sight, Daspit then took time to carefully maneuver into a textbook firing position, 875 yd (800 m) square off the target's beam, where he fired nine more Mark 14s and observed all with his periscope (despite the Japanese firing at it). All were duds.Daspit, suspicious by now he was working with a faulty production run of Mark 14s, saved his last remaining torpedo to be analyzed by experts back at base. Nothing out of the ordinary was found.

Do not fire from a "perfect" position.