Patrol boat

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.
There exist following sort of patrol boats: patrol boat fast (PBF), patrol boat with surface-to-surface missile (PBG), patrol boat inshore (PBI), patrol boat with SAM (PBM), patrol boat riverine (PBR), patrol boat with torpedo (PBT).
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. They may be broadly classified as inshore patrol vessels (IPVs) or offshore patrol vessels (OPVs). 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 100 m (330 ft) in length.
Seagoing patrol boats are typically around 30 m (100 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. Depending on their role, vessels in this class may also have more sophisticated sensors and fire control systems that would enable them to carry torpedoes, anti-ship missiles, and surface-to-air missiles.
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. Some modern patrol vessels are still based on fishing and leisure boats.
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), also known as Swiftboats, for brown water naval operations. The Patrol Boat, River (PBR, sometimes called "Riverine" and "Pibber") was a fiberglass hulled vessel also designed and used for inland river operations during the Vietnam War, and became an icon of water operations during the war due to its use in the 1979 film Apocalypse Now.
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. The largest OPVs might also have a flight deck and helicopter embarked. In times of crisis or war, these vessels are expected to support the larger vessels in a navy, though some smaller navies are mostly composed of just patrol boats.
35m Fast Patrol Vessels- USA -built by Swiftships, Commissioned in 2021
The Bangladesh Navy classified its medium size patrol ships as large patrol craft (LPC) which are armed with either anti-ship missiles or torpedoes. Those ships typically have heavier armaments but less range than OPVs.
35m Fast Patrol Vessels- USA -built by Swiftships, during the period 2010–2014
List of Irish Naval Service vessels;
Additionally, the Royal Swedish Navy also operates smaller types of patrol boats (Swedish: bevakningsbåt = "guard boat"):
The Swedish Coast Guard operate an additional 22 patrol vessels for maritime surveillance.