A patrol boat also referred to as a patrol craft , patrol ship , or patrol vessel is a relatively small naval vessel generally designed for coastal defence , border security , or law enforcement. There are many designs for patrol boats, and they generally range in size.
They may be operated by a nation's navy , coast guard , police , or customs , and may be intended for marine " blue water " , estuarine " green water " , or river " brown water " environments. Per their name, patrol boats are primarily used to patrol a country's exclusive economic zone EEZ , but they may also be used in other roles, such as anti- smuggling , anti- piracy , fishery patrols, immigration law enforcement, or search and rescue. 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.
Their small size and relatively low cost make them one of the most common naval vessels in the world. The classification of a patrol boat is often subjective, but they are generally small naval vessels that are used to patrol national waters or a certain jurisdiction.
They may be as large as a corvette or even a frigate , though the term may also be used for vessels as small as a yacht or rigid inflatable boat. They can include fast attack craft , torpedo boats , and missile boats. OPVs and medium size cutters are usually the smallest ship in a navy's fleet that are large and seaworthy enough to patrol off-shore in the open ocean , while IPVs are typically too small to do so and are instead kept in lakes or rivers , or close to coasts ; IPVs specifically used in rivers can also be called "riverine patrol vessels".
Large patrol vessels, Heavy patrol vessels and Large cutters are the largest type of patrol ships and are typically more than m ft in length. Seagoing patrol boats are typically around 30 m ft in length and usually carry a single medium caliber artillery gun as main armament, and a variety of lighter secondary armament such as machine guns , while others include the sophisticated close-in weapon system.
