Snippet of PT-18 Article:

On 7th December 1939, the US Navy contracted with the Electric Boat Company (ELCO) of Bayonne, New Jersey, to build twelve 70 foot motor submarine chasers (PTC) and ten motor torpedo boats (FT), all twenty two boats being essentially identical except for armament and minor equipment. The basic PT/PTC design was derived from the private venture motor torpedo boat (PV 70) built by Hubert Scott Paine's British Power Boat Company at Hythe in 1938. Unable to interest the Admiralty in this design, Scott-Paine turned to foreign markets and found an interested party in the US Navy. Consequently, in the summer of 1939, the Electric Boat Company purchased PV 70 and the associated manufacturing rights, the boat arriving in the United States in September of that year. Following extensive trials and some modifications required for USN service, PV 70 was accepted by the Navy as PT 9 and the contract for twenty two similar boats was awarded to ELCO.

Construction of the boats followed standard ELCO practice. The hulls were of double diagonal mahogany planking, in between which was sandwiched a layer of marine glue impregnated fabric. The decks were of similar construction, although in a chevron pattern with a kingplank running down the centreline of the boat. Coachroof and cockpit construction followed aircraft practice; thin sheets of plywood were fitted over a series of frames and stringers, much like an aircraft's fuselage. The superstructure consisted of three separate sections (engine room canopy, turret section, cockpit), each of which could be removed independently of the others. Power was provided by three 4M2500 Packard V-12 petrol engines of 1200 SHE The two wing engines faced aft and drove their shafts through Vee drives, while the centre engine drove its shaft direct.