Updates

2011 April 30 update: Additions and corrections made.

The following is information about the World War II manufacture of PT boats as numbered by the United States Navy. This information may contain errors and / or omissions. I'd appreciate it if you would let me know if you find any. Not all of the boats were placed in service by the USN, some were built for shipment to England or Russia. I've included information I've found regarding the transfers but it is most likely to contain the aforementioned errors and / or omissions. Also on this page is a brief history of the early boats and some information about the two Plywood Derbies which were part of a testing process by the USN for developing the PT boats. They were speed runs of approximately 190 miles at full throttle in open sea.

The navsource site has many images and detailed information for specific boats. Other excellent information sources are forum posts at ptboats.org and the very informative 1946 United States Navy publication "An Administrative History Of PT's In World War II". This document was digitized through a large effort by Dick Washichek and is available for download here along with many other PT related documents: http://www.ptboatforum.com/PT_Boat_Documents.html.

The next two tables are Elco specific. Much of the date information found below was taken from Steve Laroe's work found at the hazegray site. His lists detail specific dates for all boats, in many categories:

A brief overview of USN PT's 1-103

PT boats 1 and 2 were a 59' Crouch design built by Fogal Boat Yard Inc. They were powered by by two V2500-2 1200 horse power Vimalert engines, produced by the Stirling Engine Company. The boats never saw service as PT boats due to performance problems. On December 1941, the Navy changed their classification to that of small boat (C-6083 and C-6084 respectively). Ex-PT 1 was shipped to the Motor Torpedo Boat Squadrons Training Center, Melville, Rhode Island. Packard 4M-2500 engines were installed, and the boat was used throughout the war as a familiarization for motor machinists. Ex-PT 2 was assigned as an auxiliary craft at the Naval Torpedo Station, Newport, Rhode Island.

PT's 3 and 4 were 59' boats built by Fisher Boat Works. Their design was similar to the Fogal boats. They were transferred to England and / or Canada. See the "World War II US PT Boat Transfers" table for details.

PT's 5 and the tentatively designated PT 6 were 81' boats built by Higgins Industries. Originally both boats were Vimalert powered Sparkman and Stevens designs. Andrew Jackson Higgins Sr., head of Higgins Industries Inc., foresaw that the design would fall short of expectations and wanted to make design changes for PT 6. He was turned down by the Navy and built it to original plan. He used his own capital to construct another boat with his own design modifications, powered with three Packard 4M-2500 engines. The result was convincingly superior and the most successful of the boats fathered by the design competition. This boat became the official PT 6. Several credible sources list the original Sparkman and Stevens design (the tentative PT 6) as being sent to either England or Finland:

PT's 7 and 8 were 81' boats built by the USN at the Philadelphia Navy Yard. PT 8 was the only all aluminum hulled boat developed during the war. They were powered by two Allisons and one Hall-Scott. There were two Allisons of 2000 hp each, but actually they were four 1000 hp engines mounted on two common blocks. The Hall-Scott was only 550 hp, and was used for slower speeds and backing. These boats were exceptionally heavy when placed in service because the Navy yard had used destroyer fixtures and fittings on the boats. The main wing engines lacked reverse which limited tight maneuverability. The wing engines were also slow to start, they lacked self starters and depended on the Hall-Scott engines to get the boat to a speed of 15 knots, and then to drag in the larger Allisons. PT 7 was sent to England and / or Canada. See the "World War II US PT Boat Transfers" table for details. PT 8 was reclassified as a Yard Patrol / District Patrol Vessel, YP 110, on October 14, 1941.

PT 9 was a 70' British Scott-Paine designed boat built by the British Power Boat Company and purchased by Elco in 1939 for study. The three Rolls Royce Merlin engines were replaced by Packard 4M-2500 engines shortly after arrival in the US. This boat had much influence over certain key aspects of final hull specifications for the rest of the war. It was sent to England and / or Canada. See the "World War II US PT Boat Transfers" table for details.

PT's 10 through 19 were 70' boats built by Elco and were based on PT 9 with some Navy requested changes. They were powered by three Packard 4M-2500 engines. PT's 10-19 and the 77' PT's 20-44 were designed for two enclosed twin .50 caliber machine gun turrets, the Dewandre-Elco Power-Operated Machine Gun Turrets. They were found to be unsatisfactory and later Elco drawings show them replaced by open, manually operated twin .50 caliber machine gun mounts. They were sent to England.

PT's 20 through 44 were 77' boats built by Elco. They were powered by three Packard 4M-2500 engines. The design was again based on the Scott-Paine designed PT 9. The extra length was added to handle a USN change in specifications of an overall length between 75' and 82' to handle four larger torpedoes, 21" diameter as opposed to the original plan for (at least) two 18" ones. This design was the first to see combat.

PT's 45 through 48 were 77' boats built by Elco. They were powered by three Packard 4M-2500 engines. Some visible differences are that the cabin design for PT's 45-68 changed to a more streamlined shape aft of the bridge, and the forward cabin is flattened with the sides angling back like the Elco 80' boat. The new design also had four forward windshield panels as opposed to three on the earlier boats. Some good images of the differences can be found at http://www.pt-king.gdinc.com/Mysteryboats.html.

PT's 49 through 58 were 77' boats built by Elco for England for lend-lease. They were powered by three Packard 4M-2500 engines. One visible difference is that the bridge windshield is slightly different on these ten 77' boats. They were sent to England.

PT's 59 through 68 were 77' boats built by Elco for England for lend-lease. They were powered by three Packard 4M-2500 engines. They were never sent to England.

PT 69 was a 72' boat built by Huckins Yacht. It was powered by four Packard 4M-2500 engines. This boat was not placed in service as a PT. It was reclassified as a Yard Patrol / District Patrol Vessel, YP 106, September 24, 1942.

PT 70 was a 76' boat built by Higgins. It was dubbed the "Higgins Dream Boat". It was powered by three Packard 4M-2500 engines. This boat was not placed in service as a PT. It was reclassified as a Yard Patrol / District Patrol Vessel, YP 107, September 24, 1942.

PT's 71 through 94 were 78' boats built by Higgins. They were powered by three Packard 4M-2500 engines. PT's 85-94 were built for Russia although most were reassigned to England.

PT's 95 through 102 were 78' boats built by Huckins. They were powered by three Packard 4M-2500 engines. None of these boats saw combat but were used for training and homeland defense area patrol.

PT 103 began the last major change to Elco's hull design. Length was increased to 80'. They were powered by three Packard 4M-2500 engines. This design is the one most often modeled.

A brief overview of the Plywood Derbies

The two Plywood Derbies were speed runs of approximately 190 miles at full throttle in open sea. They were part of a larger USN testing process to develop PT / Motor Torpedo Boats. The public aspect of development began when the Navy Department held a design competition for 54' and 70’ class Motor Torpedo Boats, as well as a 110’ wood subchaser and a 165’ steel subchaser. It opened on July 11, 1938. For a detailed history please see the publication, from which much of the below information was taken, "An Administrative History Of PT's In World War II", available for download here: http://www.gdinc.com/Preliminary_Admin_History_PTBoat.html.

The first Plywood Derby was held on July 24, 1941 and had nine entries. The Derby course was in the waters off New London, CT. It started at Sarah’s Ledge, from there to the eastern end of Block Island, around Block Island to and around Fire Island Lightship, and then to Montauk Point whistling buoy. Conditions were a moderate swell with a cross chop. The entrants were:

Elco: PT’s 20, 30, 31, and 33
Higgins: PT’s 6, 70, and a 70' boat built for the British and powered by three Hall-Scott 900 hp engines.
Huckins: PT 69
USN: PT 8

Elco's PT 20 crossed the finish line first with a 39.72 knot average. PT 31 was second with 37.01 knots. The Navy’s entry, the very heavy PT 8, was last with a 30.73 knot average. Four of the boats which entered the run suffered structural damage of varying degrees. During the race, PT’s 33 and 70 suffered severe enough damage to withdraw, and the Higgins British boat developed engine trouble within five minutes and was forced to retire.

The contest results were questioned because of the light seas and the fact that some boats had to be ballasted due to incomplete ordnance loads. The only boats which had the complete 20,600 pound ordnance load aboard were the Elco's, while the Higgins Dream Boat (PT 70) had none of the required ordnance installations. The other boats had some equipment but not the complete load. The load was simulated with deck weights which gave an unnatural load displacement and was largely the cause of PT 70's damage because of the unrepresentative moments set up by the ballast. PT 33's failure can be accounted for by the old system of interrupted longitudinals used by Elco in its early construction.

The second Plywood Derby was held on August 12, 1941 to satisfy officials and entrants of a fair test. Before the derby, the Higgins PT 70 was repaired and the USN's PT 8 was lightened by replacing the overly heavy fixtures and fittings. The test was held at the same location on the same course except it started at Race Rock instead of Sarah’s Ledge. The distance remained the same. Sea conditions were more satisfactory, lumpy with heavy cross swell. These heavy swells ran from six to eight feet tall, with occasional swells of ten to twelve feet. The heavies and conditions encountered on the run were short steep seas running as high as fifteen feet. There were only six entries for this run:

Elco: PT’s 21 and 29
Higgins: PT’s 70, and his British boat
Huckins: PT 69
USN: PT 8

Elco's PT 21 crossed the finish line first with a 27.5 knot average. The Higgins PT 70 was a close second with 27.3 knots. PT 8 tied with PT 28 at 25.1 knots. Last was the British boat with 24.8 knots. PT 69 suffered structural damage and was forced to withdraw. For comparasion reasons a destroyer, DD441, ran the course with the PT's and finished with a 29.8 knot average. The destroyer had a running start so was up to speed at the beginning. The long range speed in rough water of the only slightly slower PT's impressed Navy officials.