In this role, they frequently became involved in firefights with enemy soldiers on boats and on the shore, were used to insert and extract Navy SEAL teams, and were employed by the United States Army's 458th Transportation Company, known as the 458th Sea Tigers.

The first craft off the assembly line, called the Mark I, was 31 feet long with a hull constructed entirely of fiberglass, a technology developed in the early 1950s.

Typically, a First Class Petty Officer served as boat captain, with a gunner's mate, an engineman and a seaman on board.

The boats were powered by dual 220 horsepower (160 kilowatts) Detroit Diesel 6V53N engines with Jacuzzi Brothers 14YJ water-jet drives.

Typical armament configuration included twin M2HB .50 caliber (12.7 mm) machine guns forward in a rotating, shielded tub, a single rear M2HB, one or two M60 7.62 mm light machine guns mounted on the port and starboard sides, and a Mk 18 grenade launcher.

Some had a "piggyback" arrangement, a .50 cal machine gun on top of an 81mm mortar;[7][8] others had a bow-mounted Mk16 Mod 4 Colt 20 mm automatic cannon, derived from the AN/M3 version of the Hispano-Suiza HS.404 and also found on the LCMs and PBRs.

Naval Reserve up until 1995 at Mare Island, California, prior to the base's closure due to BRAC action that year.

[10] In the late 1990s, what remained of the U.S. Navy's PBR force was solely in the Naval Reserve (Swift Boats had been retired from the active duty U.S. Navy immediately following the Vietnam War during the early 1970s), and was moved further inland towards Sacramento, California, the state capital, which is also intertwined with rivers.

From Sacramento, PBRs could still transit directly to and through San Francisco Bay and into the Pacific Ocean, if need be.

On March 6, 1967, United States Navy Seaman David George Ouellet was the forward machine gunner on PBR 124.

Patrick Osborne Ford was a United States Navy sailor serving on a PBR patrol boat who was killed in South Vietnam after he saved the lives of two of his shipmates.