United States
At the start of the war with Japan, the U S. steam driven Torpedo was running at a greater depth than that set, up to ten feet deeper, and the magnetic pistol just did not operate beneath the keels of the target ship.

The contact detonator also was defective, and Torpedoes exploded when hitting their targets at much less angles than the ninety degree angle which should be the perfect shot. The Bureau of Ordinance in the U S. responsible for Torpedoes refused to believe this weapon that they issued to Submarines could be in any way defective.

Lieutenant J.W Coe of U.S.S."Skipjack," wrote in June 1942, after a patrol on which he had managed to sink four ships "To make round trips of 8,500 miles into enemy waters, to gain attack position undetected within 800 yards of enemy ships, only to find that the Torpedoes run deep and over half the time fail to explode, seems to me to be an undesirable manner of gaining information which might be determined any morning within a few miles of a Torpedo station in the presence of few hazards."

On 24th of July 1943, Captain of the U.S. Submarine "Tinosa," attacked the "Tonan Maru III," a 19,000 ton Whaling Factory. Commander Daspit now conducted his own tests on the efficacy of U S Submarine Torpedoes. He fired 4 Torpedoes and believed 2 hit, but the ship did not appear to be damaged. He now fired 2 more, both hit and the ship stopped, but did not sink.

At, close range and at right angles to the target he loosed off 9 Torpedoes. All hit but not one exploded. Daspit now took his last Torpedo home.The Bureau at last admitted that the Skippers were right and Torpedoes were defective. Tests showed that defects in the firing pistol and in the depth keeping qualities were present. These problems were cured. Almost two years to react to this problem had lapsed. Submarine Captains had long reported they had heard their Torpedoes hitting their targets, and not exploding.

U.S. Mark 14 Torpedo
The Mark 14 was 21 inches in diameter, and carried a 643
ound war head, it ran for 4,500 yards at 46.3 knots, or 9,000 yards at 31 Knots.

U.S. Mark 15 Torpedo
The Mark 15 Torpedo was also 21 inches in diameter, but carried a heavier war head, one with 780 pounds of explosive; it ran for 15,000 yards at 45 knots or at 15,000 yards at a reduced speed of 26.6 knots.

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