Patrol boat

A patrol boat is a small naval vessel generally designed for coastal defence duties. They may be operated by a nation's navy , coast guard, or even 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.

Patrol boats are typically around 30m (100 ft) in length and usually carry a single gun as main armament, along with a variety of lighter secondary armament such as machine guns. They are usually diesel-powered, although some modern designs use gas turbines, and speeds are generally in the 25-30 knot range.

Examples in use around the world include the Island class, and the Pacific class.

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