The PCF (Patrol Craft, Fast) vessels - better known simply as "Swift Boats" - were a product of the Sewart Seacraft concern of Berwick, Louisiana USA which designed and constructed the boat to US Navy military specifications. The approved design was given somewhat limited offensive capabilities when compared to its more modular PBR (Patrol Boat, Riverine) brethren and was armed through machine guns, mortars and any personal weapons held by the crew. The vessel proved a fast, mobile and reliable platform from which to conduct increasingly important riverine operations during the American involvement in the Vietnam War. Nearly 200 of the type were constructed though only about 110 actually served in the war under the flag of the United States Navy. Introduction was in 1965 and global operators went on to include Panama, the Philippines and Thailand as well allied South Vietnam. Additionally, some boats were used by belligerent forces when captured.
The Swift Boat featured an identifiable profile which was dominated by the fixed, forward-set wheelhouse. Aft of the wheelhouse was the main mast assembly. The pilot's compartment was held well-forward of amidships and sported three large rectangular windows along three slightly sloped panels. Additional windows dotted the sides of the wheelhouse. Hinged access doors were fitted to the sides of the superstructure and a lower structure was integrated to the rear of the wheelhouse. An upper, open-air gun tub mounted a dual 12.7mm (.50 caliber) heavy machine gun configuration and provided the primary offense/defense for the boat. A third 12.7mm heavy machine gun was affixed to a trainable mounting at the stern and to this was added an 81mm mortar in an "over-under" arrangement. Beyond this, crews also mounted 7.62mm M60 General Purpose Machine Guns (GPMGs) for added firepower. Whatever personal weapons carried aboard by the crew could also be brought to bear in a firefight.
The Swift Boat eventually appeared across three distinct production "marks" as the Mk I, Mk II and Mk III - each form differing only slightly from the original approach. The Mark II moved the deck house more amidships and featured redesigned port hole windows for the cabin structure. The Mark III was based on the Mark II but were dimensionally larger (it bears mention that Swift Boats were not exceptionally large watercraft to begin with).
On the whole, Swift Boats managed an admirably combat record throughout the Vietnam War, operating either independently or as part of a larger patrolling force. Vessels such as this were also called upon for special forces insertion/extraction missions where their speed, riverine qualities and onboard space made then valuable. Despite their success, Swift Boats were generally susceptible to enemy rocket attacks from the shore and naval mines which forced crews to be on constant guard during missions. A typical operating crew was normally six personnel made up of an officer, boatswain, radar/communications operator, engineer and a pair of dedicated machine gunners. Power was served through 2 x Detroit Diesel marine engines, each developing 480 horsepower which gave the PCF upwards of 20 knots in ideal conditions.