Depending on the size, organization, and capabilities of a nation's armed forces, the importance of patrol boats may range from minor support vessels that are part of a coast guard, to flagships that make up a majority of a navy's fleet.
[1] During both World Wars, in order to rapidly build up numbers, all sides created auxiliary patrol boats by arming motorboats and seagoing fishing trawlers with machine guns and obsolete naval weapons.
The United States Navy operated the Pegasus class of armed hydrofoils for years in a patrol boat role.
During the Vietnam War, the U.S. Navy ordered 193 aluminum hulled Patrol Craft, Fast (PCFs),[2] also known as Swiftboats, for brown water naval operations.
Most modern designs are powered by gas turbine arrangements such as CODAG, and speeds are generally in the 25–30 knots (46–56 km/h; 29–35 mph) range.