Editing Patrol Craft Fast (section)

=== Mark I ===

The Swift Boats had welded aluminum hulls about {{convert|50|ft}} long with {{convert|13|ft|m}} beam, and draft of about five feet (1.5 m). They were powered by a pair of [[Detroit Diesel Series 71|General Motors 12V71"N"]] Detroit marine diesel engines rated at {{convert|480|hp|kW}} each, with a design range from {{convert|320|nmi|km}} at {{convert|21|knots|km/h}} to about {{convert|750|nmi|km}} at {{convert|10|knots|km/h}}.  The normal complement for a Swift Boat was six: an officer in charge (skipper), a boatswains mate, a radar/radioman (radarman), an engineer (engineman), and two gunners (quartermaster and gunner's mate). In 1969, the crew was supplemented with a Vietnamese trainee.

The first two PCFs were delivered to the Navy in late August 1965. The original water taxi design had been enhanced with two .50 caliber [[M2 Browning]] machine guns in a turret above the pilot house, an over-and-under .50-caliber machine gun – 81&nbsp;mm mortar combination mounted on the rear deck, a [[mortar (weapon)|mortar]] ammunition box on the stern, improved habitability equipment such as bunks, a refrigerator and freezer, and a sink. The 81&nbsp;mm combination mortar mounted on the rear deck was not a gravity firing mortar as used by the Army and [[United States Marine Corps|Marine Corps]], in which the falling projectile's primer struck the fixed firing pin at the base of the mortar tube, but a unique lanyard firing weapon in which the projectile was still loaded into the muzzle. The gunner could "fire at will" by the use of the lanyard. The weapon had been tested in the 1950s and discarded as the U.S. Navy lost interest in the system. The [[United States Coast Guard]] maintained the gun/mortar system before the Navy incorporated it into the PCF program.<ref>{{cite web|last=Wells II|first=William R.|title=The United States Coast Guard's Piggyback 81mm Mortar/.50 cal. machine gun|publisher=Vietnam Magazine|date=August 1997|url=http://www.pcf45.com/misfire/81-50.html|access-date=16 January 2012}}</ref><ref>{{cite web|url=http://www.pcf45.com/misfire/mortar.html|title=Notes on Mk 2 Mod 0 and Mod 1 .50 Caliber MG/81mm Mortar|author=Bob Stoner}}</ref> Many boats also mounted a single [[M60 machine gun]] in the forward peak tank, just in front of the forward superstructure.

The original order for 50 boats was followed shortly by an additional order for 54 more Mark Is.