Vietnamese River Deltas

Verified Timeline

Lore & Background

Development began after a January 1965 report from the Naval Advisory Group called for more effective riverine warfare forces. Existing French patrol craft were deemed unsuitable against heavy Vietcong presence. The first prototype was designed by Willis Slane and Jack Hargrave of Hatteras Yachts Co., ready in 90 days based on an existing sporting hull, featuring supercharged Daytona diesel engines and a 30.5-knot speed. However, the Navy awarded a contract to Uniflite for construction after trials revealed issues with the Hatteras prototype's incomplete nature. On November 29, 1965, Uniflite received an order for 140 PBRs, stipulating 120 hulls by April 1, 1966. The first Mark I came off the line on December 21, 1965, with the first 11 delivered to Cần Thơ on March 21, 1966.

In Their Own Story

Nordtvedt flew to South Vietnam in September 1966 to address deficiencies in the Mark I design based on crew suggestions. The resulting Mark II featured improved drives to reduce fouling, aluminum gunwales for wear resistance, and a flatter hull bottom for shallow water, allowing it to carry heavier weapons without performance loss. Production began in 1967 and continued until 1980, with six additional units built by River City Machine Works Inc. in 1990. These versatile boats operated in pairs under a patrol officer, often carrying an ARVN MP or interpreter for routine patrols. They faced enemy soldiers on boats and shore, inserted SEAL teams, and were even used by the Army's 458th Transportation Company, known as 'Sea Tigers,' who nicknamed them 'J-Boats' to distinguish them from Navy units.

Reader's Guide

The PBR drew only 2 feet of water fully loaded, powered by dual 220 horsepower Detroit Diesel 6V53N engines and Jacuzzi Brothers 14YJ water-jet drives, reaching top speeds of 25–31 knots depending on the load. A field modification removing armor from PBR 105 reportedly allowed it to hit 35 knots. Armament was heavy for its size: twin forward M2HB .50 caliber machine guns in a rotating shielded tub, a single rear M2HB, one or two side-mounted M60s, and a Mk 18 grenade launcher. Some featured a 'piggyback' arrangement with a .50 cal atop an 81mm mortar or a bow-mounted Mk16 Mod 4 Colt 20 mm cannon. Protection was minimal, limited to ceramic armor in the gun pit and quarter-inch steel for the coxswain's flat, relying instead on rapid acceleration and maneuverability to escape danger.

Did You Know?

• The first PBR prototype was ready 90 days after a meeting with US Navy officials in Washington D.C.
• A field modification removing armor from PBR 105 was reported to have increased its speed, but this remains an unverified anecdote.
• Mark II PBRs were built during the Vietnam War era (late 1960s–early 1970s), not in 1990.
• The Vietnam People's Navy operated captured American PBRs in significant numbers, often rearming them with domestic weapons.
• The PBR's water-jet drives could pivot to reverse direction or turn the boat within its own length.