The "devil boats" of America

The Patrol Torpedo Boat

When thinking about naval warfare in World War II, it's easy to concentrate on the titanic steel battleships; the submarines, the silent killers lurking beneath the waves; and on the carriers, the heralds of future naval warfare. This article, however, is about the unfairly overlooked Patrol Torpedo (PT) boat, the small, fast, agile warship. Given such colorful nicknames by their enemies as "mosquito fleet" and "devil boats," the PT boat proved its worth many times over.

The concept behind the PT boat was in no way a new idea by World War II. The invention of the self-propelled torpedo in the mid-19th century quickly prompted innovations in warship design. The torpedo was small and light (compared to a naval gun), and could cause a lot of damage. On the downside, a torpedo running through water with limited fuel was slower, shorter-ranged, and harder to hit with, than a shell flying through the air. These considerations prompted the question: why not build a lot of small, and therefore fast and cheap, boats, arm them with torpedoes, and have them swarm the enemy's ships? Even if many of these boats were lost, a few could still get close enough, launch their torpedoes, and knock out an enemy capital ship, causing the enemy much more economic damage than you suffered yourself. Cheap and fast boats capable of destroying much larger targets were also great raiders against enemy supply ships.

Such boats, however, would have inherent limitations. Being small and light meant they could only carry a limited amount of fuel, and would therefore have a relatively short range. The small size also meant they weren't very seaworthy in open waters. These two factors meant that torpedo boats were best used in coastal waters, not far from a base.
 
In 1938, the U.S. Navy issued a call for designs for submarine chasers and motor torpedo boats ("motor" meaning they used gasoline-fuelled engines rather than steam turbines) in various size categories. After reviewing the submitted plans, the Navy invited several manufacturers to a competitive testing of their prototypes for 70-foot motor torpedo boats. The test, which comprised of two open-ocean trials, came to be known as the "Plywood Derby," referring to the boats' building material. Three manufacturing firms became notable after the tests.

Elco, originally the Electric Launch Company, had the fastest boat in the tests, but the boat also had the widest turn radius, and, like several other competitors, suffered structural failures during testing. It also "pounded" on the water very heavily, which caused extreme exertion and fatigue in the crew. Nevertheless, a revised version of the boat eventually became the most produced PT boat. PT boats had a highly variable armament, and the revised Elco boat, being the largest at a length of 80 feet, was usually the most heavily armed due to having the most space for weapons.

The Higgins version was built by the same company that also created the famous Higgins landing craft used in Normandy on D-Day and during the island hopping campaign in the Pacific. It was very similar to the Elco boat in size and shape. Many Higgins boats were sent to Great Britain and the Soviet Union as part of the Lend-Lease program. Fewer Higgins PT boats were built than Elcos (199 vs. 326), but more of them survive, attesting their reliability.

The Huckins Yacht Corporation was a latecomer to the PT boat project. Unlike other PT boat manufacturers, they did not get government aid to expand their manufacturing facilities, and could only build a single boat a month. While few in number, the Huckins PTs proved very rugged, and they incorporated an innovative "Quadraconic" planing hull design, which eliminated much of the pounding that plagued other versions.

Finally, we must mention Vosper & Company for completeness' sake. Vospers was a British shipbuilding company, which commissioned several American boatyards to build British-designed motor torpedo boats for use by the United Kingdom and several other countries. These boats were never used by the United States Navy, but still carried the PT-xxx designation.

Regardless of the specific version, PT boats had a crew of 12 to 17, depending on the number of weapons mounted. In order to keep the boats light, cheap, and to spare strategically important materials, the double-layered hulls were built out of mahogany planks with a canvas layer between the hull layers. The planks were held together by thousands of copper rivets and bronze screws. This made repairs easy, since damage planks could be simply unscrewed, removed and replaced without having to disassemble the rest of the boat. According to some sources, a few PT boats were partially built of 3,000-year-old cedar logs recovered from a bog in New Jersey.

The wooden construction proved surprisingly sturdy. PT-109, whose crew included future President John Fitzgerald Kennedy, was cut in half when it was rammed by a Japanese destroyer, and the front half of the wreck remained afloat for 12 hours. PT-167 was hit by a torpedo that failed to detonate. The torpedo punched a hole clean through the boat's bow, but the vessel continued the fight and was repaired the next day.

True to its name, the Patrol Torpedo Boat carried torpedoes as its main armament. Early versions had either four or two tube-launched Mark 8 torpedoes. Unfortunately, America struggled to develop a high-quality torpedo for a long time, and the Mark 8, which originally entered service before World War I, was archaic and plagued by problems. If you launched your torpedoes without keeping the boat's keel sufficiently even (which is hard to when you're attacking at a high speed), the torpedo's gyroscope would cause it to lose stability. Also, the torpedo was launched from its tube by an explosion of black powder. Black powder, however, would often misfire from the high humidity in the Pacific. When a misfire happened, the torpedo would activate without leaving the tube. This was called "hot running," and would end with the torpedo's own motor overheating and exploding while still onboard the boat. Additionally, the tubes were lubricated with oil and grease, which could catch fire during launch, revealing the boat's location by smoke in the day, and by the flash at night. These obsolete weapons were replaced by Mark 13 torpedoes, normally carried by aircraft, in mid-1943. The new torpedoes had no launching tubes, and were installed rolled off into the sea from a rack.

PT boats also carried a variety of automatic guns for additional firepower against unarmored vessels, enemy aircraft, or ground troops along the shoreline. Early in the war, the standard armament was two twin .50 caliber Browning machine guns for use against planes, and some Elco boats also carried twin .30 caliber Lewis machine guns for additional firepower.
 
The number and type of guns, however, were liable to change depending on what was available. 20 mm Oerlikon autocannons were a common sight on PT boats, and crews operating near the front lines were eager to upgrade their vessels with whatever they could get their hands on.  37 mm anti-aircraft cannons, mortars and rocket launchers were often installed. A few boats, including Kennedy's P-109, were also armed with a single-shot 37mm anti-tank gun, while boats operating near Henderson Field on Guadalcanal often had aircraft guns pulled off of crashed P-39 Airacobras. Even the 40 mm Bofors gun, designed as a medium anti-aircraft gun, appeared on PT boats. Boats often also carried depth charges for anti-submarine operations, and even (rarely used) sea mine layers. These up-arming initiatives were usually driven by enterprising crews seizing ad hoc opportunities, but were often integrated into the PT boat's official design if they proved successful.

PT boats are best-known for their service in the shallow waters around Pacific atolls and islands, even though they also fought in the Aleutian Campaign and the Mediterranean. In fact, some were even present during the D-Day landings in Normandy, where they were screening landing forces from German E-boats, which were similar but larger than the PT boat. When used against enemy shipping, PT boats usually attacked at night, when their small size (and the lack of radar on most Japanese vessels) allowed them to sneak up on an enemy force and launch their torpedoes from a close range, about 1,000 yards (910 m).

PT boats did attack Japanese capital ships in the Pacific, but their success was partially due to excessive Japanese caution. The Japanese Type 93 "Long Lance" torpedo was the best in the world at the time, and the Japanese assumed that America had a comparable weapon mounted on the boats. As a result, Japanese capital ships were unnecessarily wary of attacking the small vessels.

PT boats were much more successful at attacking Japanese supply shipping. Allied air superiority meant that the Japanese were moving their supplies at night to avoid interception from the air. These convoys usually stuck to shallow waters, were larger Allied ships couldn't reach them, but they were still vulnerable to PT boats. The famous Tokyo Express, the Japanese supply line to New Guinea and the Solomon Islands, came under repeated PT boat attacks, causing severe food, supply and manpower shortage among Japanese ground troops. Due to their small size and ease of repair, PT boats could operate from a network of makeshift bases scattered over a large area, often located just a few nautical miles away from the nearest Japanese garrison of naval base, becoming an ever-present danger to the Japanese.

One difficulty PT boats faced when raiding Japanese convoys was that the Japanese Daihatsu-class barge had an extremely shallow draft of 5 feet (1.5 m), while American torpedoes had a minimum depth of 10 feet (3 m), causing the torpedoes to pass clean under the target. This was one of the driving forces behind PT boat crews' efforts to up-gun their craft with whatever weapons they could scrounge.

The most famous PT boat must certainly be the already-mentioned PT-109, which included future President John F. Kennedy among her crew. The crew's dramatic escape after being rammed by a Japanese destroyer is beyond the scope of this article, but will be featured in a future newsletter. Other "celebrity" PT boats include the squadron of four vessels that evacuated General Douglas MacArthur, his family and key members of his staff from the Philippines, running the Japanese blockade.

Save 10% now either way...