Mark 14 Torpedo
Designed in 1931, the Mark 14 Torpedo was the standard weapon of American submarines when the US entered WWII in 1941. Unlike earlier torpedoes which detonated on impact with a target ship’s hull, the Mark 14 had an advanced magnetic detonator that was supposed to set off the explosive charge directly beneath the enemy’s keel and break its back – fatal damage to any ship.
The concept was good, as it meant that a single Mark 14 would theoretically suffice to sink an enemy ship, regardless of size, unlike its predecessors which frequently required multiple torpedoes holing the enemy in various spots on the hull. However, secrecy and frugality led to the live testing of only two torpedoes – and one of the two had been a failure. A 50% test failure rate however did not give the US Navy pause and prompt it to conduct further testing or stop it from approving the Mark 14 and issuing it to the US submarine fleet as its standard torpedo in 1938.
It was only after war broke out that the torpedo’s grave flaws became apparent. Within the first month of hostilities submarine commanders correctly reported that the Mark 14 had serious problems with maintaining accurate depth so as to pass within the correct distance beneath an enemy ship’s keel; with its magnetic detonator, which frequently detonated prematurely or failed to detonate at all; with its contact detonator, which failed to set off the torpedo even when it struck an enemy’s hull at a perfect angle with a loud clang that was clearly audible in the firing submarine; and worst of all, with its tendency to boomerang, missing its target and running in a wide circle to come back and strike the firing submarine.
The US Navy ignored that report, as well as numerous reports from other submarine commanders complaining about the Mark 14. In one incident, a submarine commander fired two spreads totaling a dozen torpedoes at a large Japanese whaler, but only managed to cripple it. Then, with the enemy ship dead in the water, he maneuvered his submarine and carefully positioned it so that his torpedoes would have a perfect angle of impact, then fired off 9 more Mark 14s. Not a single one detonated.
Despite a flood of reports from its submarine commanders detailing the Mark 14’s shortcomings, it took the US Navy two years from the start of hostilities to even acknowledge the possibility that a problem might exist and to conduct tests to find out what, if anything, was wrong. The tests verified what American submariners had been complaining about for two years, and remedial steps to address the problems were finally begun – two years later than should have been the case.