Patrol Boat River PBR 31 Mk II: PBR (Patrol Boat, River), also called “Riverine” and “Pibber”, is the US Navy designation for a type of rigid-hulled patrol boat used in the Vietnam War from March 1966 until the end of 1970. They were deployed in a force that grew to 250, the most common craft in the River Patrol Force, Task Force 116, and were used to stop and search traffic in areas such as the Mekong Delta, the Rung Sat Special Zone, the Saigon River and in I Corps, in the area assigned to Task Force Clearwater, in an attempt to disrupt weapons shipments. In this role they frequently became involved in firefights with enemy soldiers on boats and on the shore. PBR's were also used to infiltrate Navy SEAL teams. The Mark II version, 32 feet long and one foot wider beam, had improved drives to reduce fouling, and aluminum gunwales to resist wear. It usually operated with four enlisted men, of which the most senior crewman was designated the boat commander. They were powered by dual 220 hp (164 kW) Detroit Diesel engines with Jacuzzi Brothers water jet drives. The boats reached top speeds of 28.5 knots (53 km/h). The boat was typically armed with twin .50 caliber (12.7 mm) machine guns (the forward '50s), an M60 7.62 mm machine gun, a Mark 18 grenade launcher, and sometimes a 20 mm cannon. The machine gunners and conning tower were protected with ceramic armor. The Patrol Boat Riverine is currently displayed at the New Jersey Naval Museum in Hackensack, NJ. The PBR was featured in the movie Apocalypse Now (1979). This is the very same type of fiberglass craft used in the film. The units using the PBRs were often called “The Brown Water Navy” (and those rivers were pretty brown) and also “Swift Boats” (and at 30 Knots fully loaded they PBRs were swift).