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Patrol Craft Fast (PCF), also known as Swift Boats, were all-aluminum, 50-foot (15 m) long, shallow-draft vessels operated by the United States Navy, initially to patrol the coastal areas and later for work in the interior waterways as part of the brown-water navy to interdict Vietcong movement of arms and munitions, transport Vietnamese forces and insert SEAL teams for counterinsurgency (COIN) operations during the Vietnam War.
Conception
The Swift Boat was conceived in a Naval Advisory Group, Military Assistance Command, Vietnam (NAVADGRP MACV) staff study titled "Naval Craft Requirements in a Counter Insurgency Environment," published 1 February 1965. It noted that "COIN water operations are difficult, demanding, and unique. A prevalent belief has been that COIN craft can readily be obtained from existing commercial and naval sources when needed. Unfortunately, no concerted effort has been made to develop COIN craft specifically suited to perform the many missions needed to combat insurgent activities."
The study went on to list characteristics of the ideal patrol craft:
Reliable and sturdy
Non-wooden hull, with screw and rudder protection against groundings
Self-sufficient for 400 to 500 mile (600 to 800 km) patrol
Speed of 20 to 25 knots (37 to 46 km/h)
Small high-resolution radar range 4 to 6 miles (7 to 11 km)
Reliable long-range communications equipment, compatible with Army and Air Force
Quiet
Armament for limited offense
Sparse berthing, no messing
Depth meter, accurate from 0 to 50 feet (15 m)
Small, powerful searchlight
The study was positively received, and the Navy began to search for sources. Sewart Seacraft of Berwick, Louisiana, built water taxis for companies operating oil rigs in the Gulf of Mexico, which appeared nearly ideal. The Navy bought their plans, and asked Sewart Seacraft to prepare modified drawings that included a gun tub, ammo lockers, bunks, and a small galley. The Navy used those enhanced plans to request bids from other boat builders, but Sewart Seacraft was selected.
The Swift Boats had welded aluminum hulls about 50 feet (15 m) long with 13 feet (4.0 m) beam, and draft of about five feet (1.5 m). They were powered by a pair of General Motors 12V71"N" Detroit marine diesel engines rated at 480 horsepower (360 kW) each, with a design range from 320 nautical miles (590 km) at 21 knots (39 km/h) to about 750 nautical miles (1,390 km) at 10 knots (19 km/h). The normal complement for a Swift Boat was six: an officer in charge (Skipper), a boatswain (Bosun's 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 mm mortar combination mounted on the rear deck, a mortar ammunition box on the stern, improved habitability equipment such as bunks, a refrigerator and freezer, and a sink. The 81 mm combination mortar mounted on the rear deck was not a gravity firing mortar as used by the Army and 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, 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. Many boats also mounted a single M60 machine gun in the forward peak tank, just in front of the forward superstructure.
Vietnam service
The first swift boats arrived in Vietnam in October 1965. Initially used as coastal patrol craft as a part of Operation Market Time to interdict seaborne supplies on their way to the Viet Cong and the North Vietnamese Army in South Vietnam. However, their shallow draft and low freeboard limited their seaworthiness in open waters. These limitations, plus the difficulties being encountered in the interior waterways by the smaller, more lightly armed PBRs led to the incorporation of Swift boats to patrol the 1,500 miles of rivers and canals of Vietnam's interior waterways. Swift boats continued to operate along the Vietnamese coastal areas, but with the start of Admiral Elmo Zumwalt's "SEALORDS" riverway interdiction strategy, their primary area of operations soon centered upon the Ca Mau peninsula and the Mekong Delta area in the southern tip of Vietnam. Here they patrolled the waterways and performed special operations, including gunfire support, troop insertion and evacuation, and raids into enemy territory.
The Mekong Delta was composed of ten thousand square miles of marshland, swamps and forested areas all interlaced by rivers and canal ways. Controlled by the Viet Cong, the interior waterways of the Mekong Delta were used to transport Viet Cong supplies and weapons.
Boats generally operated in teams of three to five. Each boat had an officer in charge, one of whom would also be placed in overall charge of the mission. Their missions included patrolling the waterways, searching water traffic for weapons and munitions, transporting Vietnamese marine units and inserting Navy SEAL teams.
When the swift boats began making forays up the waterways into the interior of the delta, they initially took the carriers by surprise, causing them to drop their materials and run off into the overgrowth. Occasionally a short firefight would break out. As it became clear that control for the waterways was being contested the Viet Cong developed a number of tactics to challenge the US Navy. They set up ambushes, built obstructions in the canals to create choke points, and began to place mines in the waterways.
For the swift boats, coming back down river was always more dangerous then going up river. The passage of a patrol assured their eventual return, providing an opportunity for the Viet Cong. Ambushes were typically short lived affairs, set up at a river bend or in a narrow canal that restricted the maneuverability of the boats. A wide variety of portable weapons were used in attacks, including recoilless rifles, B-40 rockets, .50 caliber machine guns and AK-47s, often fired from behind earthen bunkered positions. Engagements were brief and violent, with the ambushers often slipping away into the undergrowth when the boats located the source of attack and began to concentrate their return fire. When attacked the boats would accelerate out of the hot zone, turn and then return as a group, firing as many of their guns as they could bring to bear. They would power past the ambush point, turn and return to attack again till the ambushers were either killed or slipped away. Though most cruising and patrolling was done at 8 to 10 knots, the boats could reach a top speed of 32 knots. Thick brush and vegetation in the delta provided excellent cover for the escaping ambushers. Casualties taken among the river crews were high. Casualties suffered among the Viet Cong were difficult to assess, as they would take their dead and wounded away from a firefight. Discovering newly dug graveyards was one of the few ways to confirm Viet Cong losses.
The first Swift Boat to be lost during the war was PCF-4, which was lost to a mine in 1966. Two boats, PCF-14 and PCF-76, were lost in rough seas at the mouth of the Cua Viet River near the DMZ, and a third, PCF-77, was lost in a rescue effort during a monsoon at the mouth of the Perfume River on the approach to Huế. All three of these boats were lost in 1966. PCF-41 was lost that same year in an ambush when it was hit by fire from a 57 mm recoilless rifle. Its controls destroyed and coxswain killed, it ran aground at speed. When the crew ran out of ammunition it had to be abandoned. She was recovered the next day but was too badly damaged to be repaired. She was salvaged instead. PCF-43 was lost to a rocket attack in 1969. Several other Swift Boats had been lost to river mines, but had been salvaged and either repaired or used for spare parts.
The Vietnam People's Army managed to receive a number of South Vietnam's defunct PCFs after the unification of Vietnam in 1975. The PCFs were quickly used in the PAVN's operation at Thổ Chu and other islands to repel the invasion of the Khmer Rouge. The swift boats are still active in the current Vietnam army.