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Motor Torpedo Boats (PT)


Photograph of model of PT-109m, an Elco type PT boat

Naval Historical Center #USN 1145017

Torpedo boats were introduced into the world’s navies prior to the First World War.  They were small, fast boats with a low silhouette and a main armament of two to four torpedoes, intended to attack warships at night or other conditions of low visibility.  The destroyer was originally a torpedo boat destroyer, armed with rapid-fire guns to protect larger warships from torpedo boats.

During the Second World War, most navies made use of motor torpedo boats, which were small, wooden-hulled boats driven by internal combustion engines at speeds of 40 knots or more.  This was thought to give them the capability to attack by surprise and then make good their escape. However, their light construction meant that they were highly vulnerable to aircraft during daylight hours. Japanese seaplanes operating off Guadalcanal in January 1943 easily spotted the wakes of PT boats operating at night, and the boats were vulnerable to aircraft around the clock thereafter.

The U.S. Navy was enthusiastic about the motor torpedo boat concept and built hundreds of these craft for use in the South Pacific. They proved to be a disappointment in their original role, in part because of the miserable quality of U.S. torpedoes, and in part because the crews, mostly naval reservists, were inadequately trained. Hopes that PT boats could be effective as coastal defense ships were dashed when it was found that the ships were simply too noisy and unstable to make effective use of sound gear.

However, the PT boats proved useful as small gunboats, and, later in the war, some even landed their torpedo tubes to make room for more guns and a measure of armor protection. PT boats became adept at hunting Japanese barges during the New Guinea campaign. Until late mid-1943, they were the only American warships that were risked in the poorly charted waters off the north New Guinea coast, and their presence put serious pressure on Japanese logistics.

The most important American success with PT boats against major warships was probably the 7 December 1942 action, when PT boats drove off a convoy attempting to bring supplies to the Japanese forces on Guadalcanal. The PT boats sank no Japanese ships, but the Japanese convoy commander was unwilling to run their gauntlet to complete his mission.

PT boats were also used for insertion of Alamo Scouts and other covert missions. The ability of the boats to operate in darkness, their low silhouettes, and their ability to muffle their engines by ejecting the exhaust underwater (at some cost in performance) worked to their advantage on these kinds of missions.

The Japanese Navy was one of the few that made little use of motor torpedo boats. Japanese strategic planners, who focused almost exclusively on the doctrine of Decisive Battle, did not believe that these small craft could be effective in the heavy seas near Japan, where the decisive battle was expected to take place. By the time it became clear that they were fighting a very different kind of war, the Japanese were late in the game and never settled on a balanced design that could be mass-produced. The Japanese finally turned to suicide motor boats instead.

U.S. motor torpedo boat classes

Elco class

Higgins class


References

Alexander (2009)

Frank (1990)

Goldstein and Dillon (1993)
Nelson (1998)

Worth (2001)


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