PT boat
A PT boat is a motor torpedo boat used by the United States Navy in World War II. These vessels were small, fast, and inexpensive to build, and were valued for their maneuverability and speed. However, PT boats were hampered at the beginning of the war by ineffective torpedoes, limited armament, and comparatively fragile construction that limited some of the variants to coastal waters. In the US Navy they were organized in Motor Torpedo Boat Squadrons.
PT boats were very different from the first generation of torpedo boats, which had been developed at the end of the 19th century and featured a displacement hull form. These first generation torpedo boats rode low in the water, displaced up to 300 tons, and had a top speed of. During World War I Italy, the US, and UK developed the first high-performance, gasoline-powered motor torpedo boats and corresponding torpedo tactics, but these projects were all quickly disbanded after the Armistice. Design of World War II PT boats continued to exploit some of the advances in planing hull design borrowed from offshore powerboat racing and used multiple lightweight but more powerful marinized aircraft-derived V-12 engines, and thus were able to advance in both size and speed.
During World War II, PT boats engaged enemy warships, transports, tankers, barges, and sampans. Some were converted into gunboats which could be effective against enemy small craft, especially armored barges used by the Japanese for inter-island transport. Several saw service with the Philippine Navy, where they were named "Q-boats". Primary anti-ship armament on the standard PT boat was four 21-inch Mark 8 torpedoes, each of which had a TNT warhead and a range of at. Two twin.50-inch M2 Browning heavy machine guns were mounted for anti-aircraft defense and general fire support. Some boats carried a Oerlikon cannon. Propulsion was via a trio of Packard 4M-2500 and later 5M-2500 supercharged gasoline-fueled, liquid-cooled V-12 marine engines.
Nicknamed "the mosquito fleet" and "devil boats" by the Japanese, the PT boat squadrons were hailed for their daring and earned a durable place in the public imagination that remains strong into the 21st century. Their role was replaced in the U.S. Navy by fast attack craft.
Development
At the outbreak of war in August 1914, W. Albert Hickman devised the first procedures and tactics for employing fast maneuverable seaworthy torpedo motorboats against capital ships, and he presented his proposal to Rear Admiral David W. Taylor, the chief of the US Navy's Bureau of Construction and Repair. In September 1914, Hickman completed plans for a "Sea Sled" torpedo boat and submitted these to the Navy in hopes of obtaining a contract. While favorably received, Secretary of the Navy Josephus Daniels rejected the proposal since the US was not at war, but Hickman was advised to submit his plans and proposal to the British Admiralty, which was done the following month. The Admiralty found it interesting but thought that "no fast boat of 50' to 60'length would be sufficiently seaworthy", so Hickman built and launched his own privately financed sea sled capable of carrying a single 18-inch Whitehead Mark 5 torpedo. In February 1915, this Hickman sea sled demonstrated speeds in rough winter seas off Boston to both US and foreign representatives, but again he received no contracts. The Admiralty representative for this sea sled demonstration was Lieutenant G. C. E. Hampden. In the summer of 1915, Lieutenants Hampden, Bremner, and Anson approached John I. Thornycroft & Company about developing a small high speed torpedo boat, and this effort eventually led to the Coastal Motor Boat which first went into service in April 1916.
Meanwhile, in August 1915, the General Board of the United States Navy approved the purchase of a single experimental small torpedo boat that could be transportable. This contract for C-250 ended up going to Greenport Basin and Construction Company. When it was delivered and tested in the summer of 1917, it was not deemed a success, so a second boat of the sea sled design was ordered from Hickman in either late 1917 or early 1918. Using his previous design from September 1914 and the previous unsuccessful bid for C-250, the C-378 was completed and fully tested just in time to be cancelled as a result of the Armistice. With a full loaded weight of, C-378 made a top speed of with, and maintained an average speed of in a winter northeaster storm with seas, which would still be considered exceptional even 100 years later.
The sea sled did not surface again as a torpedo boat topic until 1939 but continued to be used by both the Army and Navy as rescue boats and seaplane tenders during the 1920s and 1930s. In 1922, the US Navy reconsidered using small internal combustion engine powered torpedo boats. As a result, two types— and —of British Royal Navy Coastal Motor Boats were obtained for testing. The larger boat was used for experiments until 1930. In 1938, the US Navy renewed their investigation into the concept by requesting competitive bids for several different types of motor torpedo boats but excluded Hickman's sea sled. This competition led to eight prototype boats built to compete in two different classes. The first class was for boats, and the second class was for boats. The resulting PT boat designs were the product of a small cadre of respected naval architects and the Navy.
Design competition
On 11 July 1938 the Navy solicited design proposals for four separate types of boat: a 165-foot subchaser, a 110-foot subchaser, a 70-foot motor torpedo boat, and a 54-foot motor torpedo boat.The winning design proposals would each receive a prize of $15,000 with $1,500 for designs that reached the final part of the competition each to be given out on 30 March 1939.
The larger boat proposal required vessels not to exceed 80 feet in length and to carry at least two 21-inch torpedoes, four depth charges, and two.50-cal machine guns. The performance specification was to achieve 40 knots with an operating radius of 275 miles at top speed. The smaller boat proposal required craft to weigh no more than 20 tons so that they could be easily transported by larger cargo ships. Top speed was also to be 40 knots, but specified operating radius was to be 120 miles at top speed and 240 miles at cruising speed. Armament for the smaller boats was to be either two torpedoes and two depth charges, or.50-cal machine guns and a smokescreen generator.
By September 1938 the U.S. Navy had received 24 design proposals for the small boat and 13 design proposals for the larger 70-footer. Of those proposals submitted, three 54-ft designs and five 70-ft designs were of interest, and the designers were asked to submit more detailed plans for both the 54 and 70 foot boats by no later than 7 November. On 21 March 1939 Sparkman & Stephens won the prize in the 70-foot class, and George Crouch had won the design proposal for the 54-foot class. After winning the design competition for the smaller PT boat, Crouch wrote that Hickman's sea sled design would be far superior "in either rough or smooth water to that of the best possible V-bottom or hard chine design". Earlier when sea sleds were specifically excluded, Crouch had informed the Bureau of Ships that the sea sled was the best type of vessel for the job.
Following the competition, contracts were placed for construction of boats: 25 May 1939 to Higgins Industries for two boats of the Sparkman & Stephens design, scaled up to an overall length of 81 feet; 8 June 1939 to Miami Shipbuilding and Fisher Boatworks for the Crouch design; to the Philadelphia Navy Yard for 81-foot boats designed by the Bureau of Ships. These last two boats were constructed mainly out of aluminum and had 4 engines. Higgins built an additional PT-6 "Prime" redesigned by Andrew Higgins personally using his own methods. Later that same year, Higgins built PT-70 that incorporated slight improvements over PT-6 Prime.
Later, testing revealed shortcomings that had to be fixed before the designs could meet performance specifications. As a result, the Navy ordered further investigation and refinement of the existing designs until a satisfactory working design could be obtained. At the same time, Henry R. Sutphen of Electric Launch Company and his designers visited the United Kingdom in February 1939 at the Navy's request to see British motor torpedo boat designs with a view to obtaining one that could be used as a check on the Navy's efforts. While visiting the British Power Boat Company, they purchased a private venture motor torpedo boat design—PV70, later renamed PT-9—designed by the power boat racer Hubert Scott-Paine. PT-9 was to serve as the prototype for all the early Elco PT boats. After the initial competition, in late 1939 the Navy contracted Elco to build 11 copies of PT-9.
On 11 October 1940 an agreement between the Navy and Huckins Yacht Corporation was finalized. The Navy would provide engines and Huckins would build a PT boat at their own expense, with the caveat that the boat would be offered to the Navy for a later sum. This boat later became PT-69. Huckins reported a profit of $28.60 on this transaction.
Plywood Derby
Background
In March 1941, during a heavy weather run from Key West to New York by Motor Torpedo Boat Squadron 2, Elco 70-footers pounded heavily in waves even at moderate speeds, and seas continuously broke high over the bows. Operating personnel reported extreme discomfort and fatigue. All boats suffered from some sort of structural failure: forward chine guards ripped away, bottom framing under bows broken, side planking cracked , and other weaknesses were reported. In April MTBRON 1 reported enthusiasm over the 81-foot Higgins, and with the PT-6 showing such good seakeeping, further purchase of Scott-Paine boats was unnecessary. In early 1941 the U.S. Navy Bureau of Ships lent Packard engines to both Huckins and Higgins, which wanted to build competitive boats at their own expense.A Chief of Naval Operations PT Boat Conference convened in May 1941 to discuss future PT characteristics. All PTs prior to the Elcos had been found defective, and it was probable the extended Elco would not be an improvement. The conference recommended a series of comparative tests to evaluate what turned out to be five new designs of motor torpedo boats. The conference strongly recommended that no more Elco 77-footers be ordered until the tests had shown that they were indeed satisfactory.