A patrol boat is a small naval vessel generally designed for coastal defense duties.

There have been many designs for patrol boats. They may be operated by a nation's navy, coast guard, or police force, and may be intended for marine (blue water) and/or estuarine or river ("brown water") environments. They are commonly found engaged in various border protection roles, including anti-smuggling, anti-piracy, fisheries patrols, and immigration law enforcement. They are also often called upon to participate in rescue operations.

They may be broadly classified as Inshore Patrol Vessels (IPVs) and Offshore Patrol Vessels (OPVs).

They are warships typically smaller in size than a corvette and can include fast attack craft, torpedo boats and missile boats, although some are as large as a frigate. The offshore patrol vessels are usually the smallest ship in a navy's fleet that are large and seaworthy enough to patrol off-shore in the open ocean. In larger militaries, such as in the United States military, offshore patrol vessels usually serve in the coast guard, but many smaller nations navies operate these type of ships.

During both World Wars in order to rapidly build up numbers, all sides created auxiliary patrol boats by arming motorboats and sea going fishing trawlers with machine guns and obsolescent naval weapons. Some modern patrol vessels are still based on fishing and leisure boats.

Seagoing patrol boats are typically around 30m (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 or a close-in weapon system. Depending on role, vessels in this class may also have more sophisticated sensors and fire control systems that would enable them to carry torpedoes, anti-ship and surface-to-air missiles. Most modern designs are powered by gas turbine arrangements such as CODAG, and speeds are generally in the 25–30 knot range. They are primarily used for patrol in a country's Exclusive Economic Zone. Common tasks are fisheries inspection, anti-smuggling (usually anti-narcotics) duties, illegal immigration patrols, anti-piracy patrols and search and rescue (law enforcement-type of work). 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 the navy.

Their small size and relatively low cost make them one of the most common type of warship in the world. Almost all navies operate at least a few offshore patrol vessels, especially those with only "green water" capabilities. They are useful in smaller seas such as the North Sea as well as in open oceans.

Similar vessels for exclusively military duties include torpedo boats and missile boats. The United States Navy operated the Pegasus class of armed hydrofoils for years, in a patrol boat role.

The River Patrol Boat (PBR, sometimes called "Riverine" and "Pibber") is a U.S. design of small patrol boat type designed to patrol waters of large rivers. For more examples of Patrol Boats visit http://patrolboatsworldwide.com/

Specific nations

Australia

• Attack class patrol boat (1967–1985)

• Fremantle class patrol boat (1979–2007)

• Armidale class patrol boat (2005–)

• Protector (Pacific Forum) class small patrol boat (1990s)

Bahamas

• Bahamas class 60m patrol vessel (Royal Bahamas Defence Force)

• Protector class patrol boat

Bangladesh

• Meghna class large patrol boats (Bangladesh Navy)

• 'Hainan' class patrol boat

• Kraljevica class patrol boat

• Barkat ('Haizhui' class/Type 062) small patrol boat

• Padma (Ajay) class patrol boat

• Shaheed ('Shanghai-II') class small patrol boats

Brazil

• Grajaú class offshore patrol vessel

• Bracuí class patrol vessel (ex-River class minesweeper)

• Imperial Marinheiro class offshore patrol vessel

• Piratini class patrol vessel

• J class patrol vessel

• Roraima class river patrol vessel

• Pedro Teixeira class river patrol vessel

Canada

• Kingston-class, (Canadian Forces)

• Orca-class, (Canadian Forces)

China

• Harbour security boat (PBI) - 4 newly built 80 ton class harbour security / patrol boats, and more are planned in order to take over the port security / patrol duties currently performed by the obsolete Shantou, Beihai, Huangpu, and Yulin classes gunboats, which are increasingly being converted to inshore surveying boats and range support boats.

• Shanghai III (Type 062-I) class gunboats - 2

• Shanghai II class gunboats

• Shanghai I (Type 062) classes gunboats - 150+ active and at least 100 in reserve

• Huludao (Type 206) class gunboat - 8+

• Shantou class gunboats - less than 25 (in reserve, subordinated to naval militia)

• Beihai class gunboats - less than 30 (in reserve, subordinated to naval militia)

• Huangpu class gunboats - less than 15 (in reserve, subordinated to naval militia)

• Yulin class gunboats - less than 40 (being transferred to logistic duties)

France

• P400 class patrol vessel, (French Navy)

• Floréal class frigate, (French Navy)

• OPV 54 class patrol vessel, (French Navy)

• Espadon 50 class patrol vessel, (French Navy)

Finland

• Kiisla class (Formerly Finnish Border Guard, now Finnish Navy)

• VMV-class (Finnish Navy)

Greece

Hellenic Navy

• Thetis class gunboats

• Osprey 55 class gunboats and derivatives HSY-55 and HSY-56A

• Asheville class gunboats

• Nasty class Coastal Patrol Vessels, formerly torpedo boats

• Esterel class Coastal Patrol Vessels

Hellenic Coast Guard

• Saar 4 Open Sea Patrol Vessels

• Vosper Europatrol 250 Mk1 Open Sea Patrol Vessel

• Abeking & Rasmussen Patrol Vessels

Hong Kong

Hong Kong Police Force

• Sea Panther class large command boat

Iceland

• ICGV Týr (Icelandic Coast Guard)

• Ægir class OPV (Icelandic Coast Guard)

• ICGV Óðinn (Icelandic Coast Guard)

• ICGV Þór (Icelandic Coast Guard)

India

• Car Nicobar class fast attack craft, Indian Navy

• Saryu class patrol vessel, Indian Navy

• Bangaram class patrol vessel, Indian Navy

• Sukanya class patrol vessel, Indian Navy

• Sankalp class, Indian Coast Guard

• Samar class, Indian Coast Guard

• Vikram class, Indian Coast Guard

Indonesia

• FPB 28, Indonesian Navy, 28 meter long patrol boat made by local Shipyard PT.PAL

• FPB 57, Indonesian Navy, 57 meter long patrol boat designed by Luerssen and made by PT.PAL, ASM and heli deck equipped for some version.

• PC-40, Indonesian Navy, 40 meter long FRP/Aluminum patrol boat, locally made by in house Navy's workshop.

Ireland

• Róisín-class, (Irish Naval Service)

• LÉ Eithne (P31), Irish Naval Service

Israel

• Dabur class patrol boats - Israeli Navy

• Super Dvora Mk II class patrol boats - Israeli Navy

• Dvora - Israeli Navy

• Super Dvora Mk II - Israeli Navy

• Super Dvora Mk III - Israeli Navy

• Shaldag class fast patrol boats

• * Shaldag Mk II - Israeli Navy

• Nachshol class patrol boats (Stingray Interceptor-2000) - Israeli Navy

Italy

• Zara class, (Italian Guardia di Finanza)

• Saettia class, (Italian Coast Guard)

• Diciotti class, (Italian Coast Guard)

• Cassiopea class, (Italian Marina Militare)

• Cassiopea II class, (Italian Marina Militare)

• Esploratore class, (Italian Marina Militare)

• Comandanti class, (Italian Marina Militare)

Japan

• Shikishima, (Japan Coast Guard)

Malaysia

• Kedah class offshore patrol vessel, (Royal Malaysian Navy)

Mexico

• Uribe class, offshore patrol vessel (Mexican Navy)

• Holzinger class, offshore patrol vessel (Mexican Navy)

• Sierra class, offshore patrol vessel (Mexican Navy)

• Durango class, offshore patrol vessel (Mexican Navy)

• Oaxaca class, offshore patrol vessel (Mexican Navy)

• Azteca class, coastal patrol boat (Mexican Navy)

Netherlands

• Future Dutch Navy OPV's (Koninklijke Marine)

New Zealand

• (Royal New Zealand Navy) (2008)

• (Royal New Zealand Navy) (2008)

• (Royal New Zealand Navy)(1983 - 2008)

Norway

Royal Norwegian Navy

• Rapp-class

• Tjeld-class

• Storm-class

• Snøgg-class

• Hauk-class

• Skjold-class

• Barentshav class OPV (Norwegian Coast Guard)

• Nordkapp class OPV (Norwegian Coast Guard)

• Nornen class (Norwegian Coast Guard)

Philippines

Philippine Navy

• Mariano Alvarez class

• Aguinaldo class

• Kagitingan class

• Tomas Batillo class

• Conrado Yap class

• Jose Andrada class

Russia

• Mirage-class (Type 14310) (Russian Navy)

Singapore

• Fearless-class (Republic of Singapore Navy)

Sri Lanka

• Jayasagara class (Sri Lanka Navy)

• Colombo class (Sri Lanka Navy)

South Korea

• Chamsuri-class (Republic of Korea Navy)

Spain

• Descubierta class

• Serviola class

• Anaga class

• Barceló class

• Toralla class

• Conejera class

• Descubierta class

• Chilreu class

• P111 class patrol boat

• Cabo Fradera class

Thailand

• Pattani-class OPV (Royal Thai Navy)

United Kingdom

• Motor Launch of World War II

• Harbour Defence Motor Launch of World War II

• River class patrol vessel

• Castle class patrol vessel

• Archer class patrol vessel

• Island class patrol vessel

United States

• List of patrol vessels of the United States Navy

• Eagle class patrol craft of World War I and World War II

• PC Patrol Craft of World War II

• Cyclone class patrol ship

• Island class cutter (United States Coast Guard)

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