Riverine command boats or RCBs, are actually Swedish CB-90s and are a type of fast attack craft. In a number of pictures released by the U.S. Navy, the boats are outfitted with a number of light, medium and heavy weapons including .50 caliber heavy machine guns and GAU-19 miniguns. Approximately 50 feet long, the CB-90s can reach speeds up to 40 knots on the water, according to the Swedish Navy.
RCB’s can carry contingents of infantry and special operation forces and are often crewed by sailors in Riverine squadrons, known by some as River Rats. The riverine force came of age in the Vietnam War in what was then known as the Brown Water Navy. In the 1960s and early 1970s boats such as Patrol Boat, River (from ‘Apocalypse Now’ fame) and Swift Boats were the River Rats vessels of choice.