The failures of American torpedoes in the early half of the war was not due to any single issue, but was rather a unique constellation of factors that severely degraded this weapon system's effectiveness.

The standard American submarine torpedo at the start of the war, the Mk. 14, was on paper a state of the art design and that technological novelty proved to be its major Achilles heel. The Bureau of Ordnance expected this wet-heater torpedo to be the solution to anti-torpedo developments like bulges by having a revolutionary exploder, the Mark 6, which would be triggered magnetically as the deep-running torpedo ran under the keel of the target. These innovations made the Mk 14 a rather expensive piece of military equipment developed during the Depression and the USN's testing regime with the torpedo was very anemic. The practice torpedoes had their warheads filled with water for easy recovery. This altered the torpedoes' performance as the buoyancy of water was not the same as TNT or other explosive material. The practice torpedoes thus were lighter than live torpedoes. This actually masked an important defect of the Mk. 14: its depth-keeping sensor was poorly located on the aft-end of the weapon. This location exposed the sensor to Bernoulli principle meant that the faster the torpedo traveled, the torpedoes' poorly fitted sensor, which operated on water pressure, the more likely it was to give a false reading. The few practice runs of the Mk. 14 in peacetime were conducted at the low-speed settings for better observation and recovery, so the sensor problem remained invisible. The result was that the test Mk. 14 torpedoes ran as designed, but the live torpedoes had a marked tendency to run much deeper than what their torpedomen had set them. This made the early-war failures of the Mk. 14 even more bitter to USN submariners because all the data they had suggested their torpedoes functioned as designed.

But the problems of the Mk. 14 were not just limited to poor depth-keeping. The Mk. 6 soon proved to to be near useless in combat when set to magnetic explosions. The exploder caused the torpedoes to detonate prematurely. As a top-secret design, the Mk. 6 had an even less rigorous testing regimen than the Mk. 14 as the BuOrd kept this component as something of a secret within the submarine force and was loath to expend them on anything but controlled tests. The result was that the numerous bugs in the exploder remained undiscovered until they were exposed to combat conditions. The exploder worked better when set to contact, but this meant that the USN's submarines had to break from established attack doctrine to best make use of the contact setting. Even then, poor quality control meant that the contact fuses were also prone to malfunction and USN sub skippers soon discovered that the contact exploders worked best at oblique angles, which was again a break from established doctrine and training.

But the poor quality control and anemic testing regimen were part of a larger problem with BuOrd, which refused to believe that its wonder weapons did not function as planned. This was symptomatic of larger problems within BuOrd and torpedo procurement. The Newport Torpedo Station had a monopoly on prewar US torpedo design and this inculcated a insular approach to torpedo design. When reports of the malfunctions filtered back to the States, both the BuOrd and Newport had a tendency to blame either poor workmanship, labor relations at Newport were quite poor, or misuse by operational commanders. It was only after evidence became overwhelming that these torpedoes were malfunctioning that a series of tests under realistic conditions proved that the Mk. 14 was quite flawed as designed.

One solution, and one the BuOrd was reluctant to engage, was to open up torpedo manufacturing to other suppliers. The British supplied the Americans with captured German G7e electric torpedoes and the Westinghouse corporation made its own variant, the Mk 18. After the bugs were worked out, the Mk. 18 proved to be a popular torpedo among submarine skippers in the latter part of the war. The Mk. 14 also had many of its bugs ironed out by an adequate regime of testing. In one telling example that was in stark contrast to the parsimonious prewar testing, the submarine Muskallunge was authorized to fire as many live torpedoes as possible to find dud Mk. 14s. Additionally, practice rounds now had filler that simulated the warhead's weight more realistically. The depth-keeping sensor was relocated and a number of defects in the exploder were ironed out.

The failures of American torpedoes were obvious and quite preventable in hindsight. Bleeding edge technology often necessitates thorough testing to prove the concept and the magnetic Mark 6 is an example of how not to deploy such a design. Additionally, while realistic testing conditions may be expensive, it also can expose weaknesses in both technology and doctrine. The closed circuit of the BuOrd and Newport TS also fostered a degree of group-think about the torpedoes' efficacy and thus they refused to believe reports that questioned their view of reality. Much of the legwork resolving these torpedoes' problems came from outside these two institutions, with Vice Admiral Charles Lockwood conducting a series of investigations into torpedo failures that exposed the various problems with torpedo design.

Sources

Campbell, N. J. M. Naval Weapons of World War Two. Annapolis, Md: Naval Institute Press, 1985.

Newpower, Anthony. Iron Men and Tin Fish The Race to Build a Better Torpedo During World War II. Westport, Conn: Praeger Security International, 2006.