A picket boat is a type of small naval craft. These are used for harbor patrol and other close inshore work, and have often been carried by larger warships as a ship's boat. They range in size between 30 and 55 feet. Patrol boats, or any craft engaged in sentinel duty, are sometimes referred to as picket boats, using "picket" in the generic sense, even if much larger than actual picket boats.
The Union's long steam-powered Picket Boat Number One sank the Confederate ironclad Albemarle in 1864.. The boat was armed with a 12-pounder Dahlgren gun and a spar torpedo, of which the latter was employed in sinking Albemarle. The Union's Potomac Flotilla also employed some picket boats. A number of American warships of the 19th century carried picket boats, such as the , and others. In the early 1920s, during Prohibition, the United States Coast Guard built a fleet of picket boats to intercept rum runners, supplementing the larger and more seaworthy cutters and patrol boats. These boats were about long, had no main fixed armament, and cost about to build. A later picket boat, built between 1932 and 1943, was long and also had no large main armament.
Britain
A long-serving 19th-century British picket boat, carried on capital ships, was a model introduced in 1867 which saw wide service in World War I and even some limited service in World War II. The typical main armament during most of this boat's service life was a Hotchkiss 3–pounder, adopted by the Royal Navy in 1886. British pre-dreadnoughts, including and, carried picket boats. The P1000 Class Picket Boat is a current British Royal Navy boat, in length, formerly carried on destroyers but now used only for training.
Germany
The Königsberg–class cruisers of 1905 and 1915 carried a picket boat; the Königsbergs of 1927 carried two. The Dresden class of a similar era carried one, as did the Wiesbaden–class. Larger ships also carried picket boats: The Nassau–, König–, and Bayern–class battleships, the SMS Seydlitz, and the Derfflinger–class battlecruisers all carried one each.
