PF. et all:

The U.S. Navy had three distinct problems with the Mark 14 Mod 3A steam torpedo at the outset of WWII.

1. Depth control - The torpedo ran about 11 feet deeper than set. This was corrected by changing the location of the sea-pressure (sensor) inlet to the midship section of the afterbody.
2. Magnetic influence exploder mechanism Mark VI - The exploder was built at NTS
Newport, RI. which is about 60 degrees latitude. The torpedoes were being used in the south Pacific, near the equator and the exploder mechanism would result in a premature detonation. The magnetic-influence portion of the Mark VI exploder
mechanism was disabled later.
3. Contact exploder - The contact exploder mechanism was mounted on the same base-plate of the magnetic influence portion. When the torpedo struck the target head on, (at a speed of 43.5 knots), the firing pin block assembly was jammed due to the bending of the 4 mounting legs, and no detonation occurred. It was discovered that when the target was struck at an angle, the percentage of successes increased. A quick fix by the torpedo shop personnel consisted of making the firing pin block assembly from aluminum taken from propellors of crashed Japanese planes.

Hope this helps,

ROBERT M.