Patrol boats are lightly armed, fast boats or small to medium-sized vessels of the navy, coast guard, police or customs.
The term is somewhat fuzzy used for very different vehicles. Both the size and equipment and armament of the patrol boats differ according to the various conditions of use. They are used against smugglers, terrorists, illegal immigrants, etc.. Offshore patrol boats ( so called off shore patrol vessels ) are designed for longer trips and have many feature helipads.
Military patrol boats are used among other things for reconnaissance, surveillance and security in the coastal zone. In order to provide the requisite large number of vehicles, civilian ships have been as fishing vessels and yachts requisitioned and used as patrol boats during the world wars.
The Bredstedt the German Coast Guard
The U. Diciotti (CP- 902) of the Guardia Costiera
A patrol boat of the Canadian Coast Guard
Patrol boat Holnis German customs
The trawler used as anti-submarine trawler Lady Shirley of the Royal Navy