PT (Patrol, Torpedo) boats were small, fast, inexpensive and expendable vessels employed by the U.S. Navy for short range oceanic scouting, and they were armed with torpedoes and machine guns for cutting enemy supply lines and harassing enemy forces. Forty-three PT squadrons, each with twelve boats were formed during World War II by the U.S. Navy, and PT boat duty was very dangerous and the squadrons suffered an extremely high loss rate in the war. The boats were valued for their high speed and maneuverability, however their performance was hampered at the beginning of the war by ineffective torpedoes, limited armament, and comparatively flimsy construction that limited some of them to coastal waters operations.
The WWII PT boats exploited some of the advances in planing hull design borrowed from powerboat racing and so were able to be constructed larger in size than their WWI counterpart “Torpedo Patrol boats” due to advancements in hull and engine technology.
Therefore, World War II PT boats that were produced that were capable of engaging enemy warships, transports, tankers, barges, and sampans, and as gunboats they were effective against enemy small craft, especially armored barges used by the Japanese for inter-island transport.
The PT’s boats primary anti-ship armament were four 2,600 pound Mark 8 torpedoes that could be launched from 21-inch Mark 18 torpedo tubes having and had a 466-pound TNT filled warhead, a range of 16,000 yards with a running speed of 36 Kts. Additionally, twin .50 caliber machine guns were mounted for anti-aircraft defense and general fire support, and some boats had a 20 mm Oerlikon cannon installed. Their propulsion was provided via a trio of Packard 4M-2500 and later 5M-2500 supercharged gasoline-fueled, liquid-cooled marine engines.
Nicknamed "the mosquito fleet" and "devil boats" by the Japanese, the PT boat squadrons became renowned for their daring and cunning, and earned a durable place in the public imagination that remains strong even today.
At the outbreak of WWI in 1914, W. Albert Hickman developed the first procedures and tactics for employing fast maneuverable seaworthy torpedo motorboats against capital ships. At first the concept was deemed undesirable by the U.S. Navy, the British Royal Navy and others. However eventually the concept got legs and the U.S. Navy renewed their examination into the idea by requesting competitive bids for several different types of motor torpedo boats. The competition dubbed “The Plywood Derby” led to eight prototype boats built to compete in two different classes. The first class was for 54-foot boats, and the second class was for 70-foot boats. The resulting PT boat designs were the product of a small cadre of respected naval architects, and the Navy.
And, one of the winning designs resulted in the eventual construction of the three boats built by Andrew Higgins of Higgins Industries in New Orleans. The boats were PT-5 and PT-6 and then PT-6 “Prime” which was redesigned by Andrew Higgins personally using his own methods. Then, later that same year, Higgins was to build PT-70, at their own expense, that incorporated slight improvements over PT-6 Prime.
About this same time Henry R. Stuphen of Electric Launch Company (Elco) and his designers traveled to the United Kingdom, at the Navy's request, to review British motor torpedo boat designs with the intention of obtaining one that could be used as a check on the Navy's efforts. While visiting the British Power Boat Company, they purchased a 70-foot design (PV70) later re-designated PT-9, designed by Hubert Scott-Paine, and the PT-9 design served as the prototype for all the early Elco PT boats.
The Elco Naval Division boats were the longest of the three types of PT boats built for the U.S. Navy and used during World War II and by war's end, 326 more of the Elco 80 ft. boats were built; more than any other type of motor torpedo boat. The 80-foot wooden-hulled craft were classified as boats in comparison with much larger steel-hulled destroyers, but were comparable in size to many wooden sailing ships throughout history having a 20 ft. 8 in beam, Although often said to be made of plywood, they were actually constructed of two diagonal layered inch thick mahogany planks, with a glue-impregnated layer of canvas in between. And, holding it all together were thousands of bronze screws and copper rivets. This type of construction made it possible for battle damage to their wooden hulls to be easily repaired at the front lines by base force personnel.
As well, Higgins Industries produced 199 of the 78 foot boats PT-71, PT-235, PT-265 and PT-625 classes had the same beam, full load displacement, engines, generators, shaft horsepower, trial speed, armament, and crew accommodation as the 80 foot Elco boats. However, many Higgins boats were sent to the Soviet Union and Great Britain at the beginning of the war, so many of the lower-numbered squadrons in the U.S. Navy were made up exclusively of Elcos. U.S. Navy PT boats were organized into Motor Torpedo Boat Squadrons designated as MTBRONs or simply RONs. The first Higgins boats for the U.S. Navy were used in the Battle for the Aleutian Islands at Attu and Kiska as part of Squadrons 13 and 16, and others from RON15 and RON22 in the Mediterranean Sea against the Germans. They were also used during the D-Day landings in 1944.
Even though only half as many Higgins boats were produced, far more survive today with a total of seven hulls, three of which have been restored to their World War II configuration, than do the more numerous Elco boats. Of the Elco boats, only three hulls are known to exist as of 2016.
As a testament to the durability of their type of construction, several PT boats withstood catastrophic battle damage and still remained afloat as in the most notorious case of future President John F. Kennedy's PT-109. Kennedy’s 80 foot Elco boat was operating in the Solomon Islands in the South Pacific and rendezvoused with fourteen other PT boats for a nighttime attack of four enemy destroyers and supply ships of Japan’s “Tokyo express”. Most of the PT boat attack force fired their compliment of torpedoes and headed for home, but three boats stayed behind including the 109. Subsequently, in the confusion and darkness at sea, Lieutenant Kennedy noted a vague shape approaching the 109 and he assumed it was a sister PT boat, but soon discovered it was the Japanese destroyer Amagiri. Kennedy attempted to swing his boat into position to fire a torpedo but was not quick enough. The much larger destroyer hit the 109 broadside at full speed nearly splitting the much smaller wooden boat in half, but the forward hull section remained afloat for nearly twelve hours with the crew hanging on it for a life raft. After the decision was made to abandon ship, Kennedy and the surviving crewman swam nearly three miles to a small island where they lived for a week with the aid of natives until Kennedy and the 109’s surviving crew were rescued by PT-157.
PT boats were well armed with numerous automatic weapons and common to all US PT boats were the two twin M2 .50 caliber machine guns. Early PT boats, Elco PT20 through PT44 mounted Dewandre Plexiglas-enclosed hydraulically operated rotating turrets. But, soon after the attack on Pearl Harbor the Dewandre turrets were replaced on the entire PT boat fleet with open ring twin mounts. The ring mount was designed by both Elco and Bell, and designated Mark 17 Twin .50 caliber aircraft mount. Part of the Mark 17 Mod 1 and Mod 2 ring mount consisted of the Bell Mark 9 twin cradle. Another automatic weapon commonly mounted on PT boats was the 20 mm Oerlikon cannon and on early series of boats, the cannon was mounted on the stern. However, later on in the war, several more of these 20 mm cannons were added amidships and on the forward deck.
Forward of the chart house of some early Elco 77-foot boats were twin .30 cal. Lewis machine guns on pedestal mounts. And, beginning in mid-1943, some boats were fitted with one or two .30 cal. Browning machine guns on the forward torpedo racks on pedestal mounts.
Occasionally, some front line PT boats received ad-hoc up-fits at forward bases where they mounted such weapons as 37mm aircraft cannons, rocket launchers, or mortars. And then when these weapons were found to be effective they were incorporated into new construction PT boats as original armament. One such field modification was made to Kennedy's PT-109, which was equipped with a single-shot Army M3 37mm anti-tank gun that her crew had commandeered; they removed the wheels and lashed it to 2x8 timbers placed on the bow just the night before she was lost. The larger punch of the 37mm round was desirable, but the crews looked for something that could fire more rapidly than the single-shot army anti-tank weapon. Their answer was found in a the 37mm Oldsmobile M4 aircraft automatic cannon that had been cannibalized from a crashed P-39 Airacobra fighter plane at Henderson Field, Guadalcanal. After having demonstrated its value on board PT boats, the M4, and later M9 cannon was installed at the factory. The M4/M9 37mm auto cannon had a relatively high rate of fire of 125 rounds per minute with a large volume magazine of 30 rounds. These features made it highly desirable due to the PT boat's ever-increasing requirement for improved firepower to deal effectively with the Japanese Daihatsu-class barges which were largely immune to torpedoes due to their shallow draft. And, by the war's end, most USN PTs had been equipped with these weapons.
The installation of the larger-bore cannons culminated in the fitting of the 40mm Bofors gun on the aft deck in mid-1943 and it had an immediate positive effect on the firepower obtainable on PT boats. The Bofors cannon had a firing rate of 120 rounds/min using four round clips and had a range of 5,420 yards. The gun was manned by a four man crew and was used against aircraft targets as well as shore bombardment and enemy surface craft.
In the Solomon Islands in 1943, three 77-foot PT boats, PT-59, PT-60, and PT-61, were converted into "PT gunboats" by stripping them of all the original armament except the two twin .50 cal. gun mounts, then adding two 40mm and four twin .50 ca. mounts and Lieutenant Kennedy was the first commanding officer of PT-59 after its conversion. On 2 November 1943, PT-59 participated in the rescue of 40 to 50 Marines from Choiseul Island and a foundering landing craft which was under fire from Japanese soldiers on the beach.
As well, towards the end of the war in 1945, PTs were equipped with two eight-cell Mark 50 rocket launchers, launching 5-inch spin-stabilized flat trajectory Mark 7 and/or Mark 10 Rockets with a range of 11,000 yards. These 16 rockets plus 16 reloads gave them as much firepower as a destroyer's 5-inch guns, and by war's end the PT boat had more "firepower-per-ton" than any other vessel in the U.S. Navy.
PT boats also commonly carried between two and eight U.S. Navy Mark 6 depth charges in roll-off racks and sometimes they were used as a last-ditch weapon to deter pursuing destroyers. The depth charges could be set to go off at 100-foot depth and by the time it exploded, the pursuing destroyer might be above it.
With the exception of the experimental PT boats, all USN PT boats were powered by three marine modified derivations of the Packard 3A-2500 V-12 liquid-cooled, gasoline-fueled aircraft engine. Improvements upon Packard's World War I Liberty L-12 2A engine, the successive "M" for "marine" designated 3M-2500, 4M-2500, and 5M-2500 generations all featured slight changes and more power. Their superchargers, intercoolers, dual magnetos, and two spark plugs per cylinder reflected their aircraft origins.
Fuel consumption of any version of these engines was exceptionally substantial, and a PT boat carried 3,000 gallons of 100 octane aviation fuel, enough for an 4M-2500 equipped boat to conduct a maximum 12-hour patrol. Some 200 gallons an hour were consumed at a cruising speed of 23 knots, increasing to 500 gallons per hour at top speed. And, hull fouling along with engine wear could both decrease top speed and increase fuel consumption materially.
PT boats operated in the southern, western, and northern Pacific, as well as in the Mediterranean Sea and the English Channel.
Originally conceived as anti-ship weapons, PT boats were publicly credited with sinking several Japanese warships during the period between December 1941 and the fall of the Philippines in May 1942. Attacking at night, PT crews may have sometimes failed due to possible torpedo failures. Although the American Mark 8 torpedo did have problems with porpoising and circular runs, it could and did have success against common classes of targets. However, their Mark 3 and Mark 4 exploders were not subject to the same problems as the Mark 6 exploders did on U.S. submarines' Mark 14 torpedoes. Introduction of the Mark 13 torpedo to PT boats in mid-1943 all but eliminated the early problems that the boat crews had with their obsolete Mark 8s.
PT Boats would typically attack at night and their cockpits were protected against small arms fire and splinters by armor plating. However, direct hits from Japanese guns could and did result in catastrophic gasoline explosions with near-total crew loss. And, they feared attack by Japanese seaplanes which were hard to detect even with radar, but which could easily spot the phosphorescent wake left by PT propellers. Bombing attacks killed and wounded crews even with near misses, and there are several recorded instances of PT boats trading fire with friendly aircraft, a situation also familiar to U.S. submariners. As a result, several PT boats were lost due to "friendly fire" from both Allied aircraft and destroyers.
Initially, only a few boats were issued primitive radar sets, however U.S. Navy PTs were eventually fitted with Raytheon SO radar which had a 17 nm range. And, having radar gave Navy PTs a distinct advantage in intercepting enemy supply barges and ships at night. So, as more PTs were fitted with dependable radar they developed superior night-fighting tactics and used them to locate and destroy many more enemy targets. Consequently, during the Guadalcanal and Solomon Island campaigns in 1942–1943, the PT boats of Squadrons 2, 3, 5 and 6 would lie in wait to ambush a target from torpedo range, generally about 1,000 yards.
And, during some of these nighttime attacks the PT boat positions may have been given away by a flash of light caused by grease inside the black-powder-actuated Mark VIII torpedo tubes catching fire during the launching sequence. In order to evade return fire from the enemy ships, the PT boats could deploy a smoke screen using stern-mounted generators. Beginning in mid-1943 the old black powder-actuated Mk13 torpedo tubes loaded with Mark 8 torpedoes were removed and replaced with a newer style of torpedo launcher. The new Mark 1 "roll-off" torpedo launcher rack which was loaded with an improved Mark 13 aerial torpedo effectively eliminated the telltale flash of light from burning grease. And, the improved launcher did not use any form of explosive to launch the torpedo, and it weighed about 1,000 pounds less than the old tube style launchers.
There were numerous engagements between PTs and capital ships as well as against Japanese shipborne resupply efforts dubbed "The Tokyo Express" operating in New Georgia Sound or "the Slot", but they were substantially undermined by defective Mark 8 torpedoes. The Japanese were initially cautious when operating their capital ships in areas known to have PT boats on patrol since they knew how dangerous their own Type 93 torpedoes were and assumed the Americans had equally lethal weapons. Our PT boats at Guadalcanal were credited for several sinkings and successes against the vaunted Tokyo Express. And, in several engagements the mere presence of USN PTs was sufficient enough to disrupt heavily escorted Japanese resupply activities at Guadalcanal. And the PT mission in the Solomon Islands was deemed a success.
Some boats served during the Battle of Normandy and during the D-Day invasion, PTs patrolled the "Mason Line", forming a barrier against the German S-boats attacking the Allied landing forces. And, they also performed lifesaving and anti-shipping mine destruction missions during the invasion.
Perhaps the most effective use of PTs was as "barge busters". Since both the Japanese in the New Guinea area and the Germans in the Mediterranean had lost numerous resupply vessels to Allied air power during daylight hours, each attempted to resupply their troop concentrations by using shallow draft barges at night in very shallow waters. The shallow depth meant Allied destroyers were unable to follow them due to the risk of running aground and the barges could be protected by an umbrella of shore batteries.
The efficiency of the PT boats at sinking the Japanese supply barges was considered a key reason that the Japanese had severe food, ammunition, and replacement problems during the New Guinea and Solomon Island campaigns and that made the PT boats prime targets for enemy aircraft. The use of PT boat torpedoes was ineffective against these sometimes heavily armed barges, since the minimum depth setting of the torpedo was about 10 feet and the barges only drew just 5 feet. So in order to accomplish the task PTs in the Mediterranean and the Pacific installed more and heavier guns which were able to sink the barges. And, one captured Japanese soldier's diary described their fear of PT boats by describing them as "the monster that roars, flaps its wings, and shoots torpedoes in all directions."
Though their primary mission continued to be attack on surface ships and craft, PT boats were also used effectively to lay mines and smoke screens, coordinate in air-sea rescue operations, rescue shipwreck survivors, destroy Japanese suicide boats, destroy floating mines, and to carry out intelligence or raider operations.
PT boats lacked a large capacity refrigerator to store sufficient quantities of perishable foods. Therefore, while docked, PT boat squadrons were supported by PT boat tenders or base facilities which supplied boat crews with hot meals. As the boats were usually stationed near the end of the supply chain, their crews proved resourceful in bartering with nearby ships or military units for supplies, and using munitions to mass harvest their own fish.
At the end of the war, almost all surviving U.S. PT boats were disposed of shortly after V-J Day resulting in hundreds of boats being deliberately stripped of all useful equipment and then dragged up on the beach and burned. This was done to minimize the amount of upkeep the Navy would have to do, since wooden boats require heavy and continuous maintenance, and they were not considered worth the effort. The boats also used a lot of high octane gasoline for their size, making them too expensive to operate for a peacetime navy. Much of this destruction occurred at PT Base 17, on Samar, Philippines, near Bobon Point.
However, some PTs did survive the war and are still around today. Completed and launched in the summer of 1945 by Elco, PT- 617 was assigned to Patrol Torpedo Squadron 42 but she didn’t see much if any combat with the war’s end rapidly approaching. So she was mostly used to stimulate morale on the home front with a Victory Loan Bond Drive. Consequently, after the war, the 617 was sold to a private owner and was used over the years as a yacht, as a salvage vessel and as a diving platform in Florida with the subsequent names of Big Red Cock and Dragon Lady. Then, PT Boats, Inc., a nonprofit organization of World War II PT boat veterans, bought the boat and in 1979 began restoration work until September 1, 1985 when PT-617 went on display at the private non-profit Battleship Cove in Fall River, Massachusetts. PT-617 was added by the National Park Service’s National Historic Landmarks and the National Register of Historic Places on December 20, 1989.
Another survivor, PT-658 was built in 1945 by Higgins in New Orleans. This boat was originally slated to join Squadron 45 and assigned to the Pacific Fleet, but with the war coming to a close she too never saw action. So, in 1958, the 658 was sold to a private individual in the Oakland and Alameda, California area and renamed Porpoise. Then again, PT Boats, Inc. came to the rescue and bought and restored her between 1995 and 2005. And now, she is fully functional, afloat, and is the only restored US Navy PT Boat that is operational today. PT-658 is floating on the north bank of the Willamette River, housed in a custom-built boathouse in Portland Oregon at the PT-658 Heritage Museum located at the Swan Island Industrial Park. PT-658 was added to the National Park Service’s National Register of Historic Places in 2012.
The original 1962–66 McHale's Navy TV series used a Vosper design PT-694. Prior to starring in the television series the boat was purchased as war surplus by Howard Hughes and was used as the camera chase boat when the Spruce Goose made its one and only flight.
In John Ford's 1945 war film, They Were Expendable, two 80-foot Elcos were used during filming along with four former RON 14 78-foot Huckins.
For the 1962 movie PT-109, several 82-foot USAF crash rescue boats were converted to resemble 80-foot Elcos when the few surviving boats were found to need too much work to make them seaworthy for use during the film.