This glossary defines the various types of ships and accessory watercraft that have been used in service of the United States. Such service is mainly defined as military vessels used in the United States Navy and United States Coast Guard, as well as the defunct, incorporated, or renamed institutions such as the United States Revenue Cutter Service. Service of the United States can also be defined in this context as special government missions in the form of expeditions, such as the Wilkes Expedition or the North Pacific Exploring and Surveying Expedition. The scope of the glossary encompasses both the "Old Navy" of the United States (sail or later steam vessels, with ship type named for the rigging or propulsion method [ex. steamer, cutter, schooner]), from its beginnings as the "Continental Navy", through the "New Navy" (revolutionary steam or fueled vessels, with naming derived from a hull classification scheme) and up to modern day. The watercraft included in the glossary are derived from United States ships with logbooks published by the National Archives and Records Administration.

A

Ammunition ship A type of auxiliary ship specifically designed to store and transport ordinances or ammunition to combat ships.

Armed merchantman A merchant or civilian vessel armed for military purposes, like water defense or raiding. May also be generally referred to as a "merchant raider".

Armed stores ship See "combat stores ship".

Armed yacht A yacht that was armed with weapons for naval service. Originally applied to small, fast and agile naval vessels, typically privately owned and expropriated or purchased for government use in times of war, most famously in World War II.

Armored cruiser A type of warship of the late 19th and early 20th centuries. It was designed to operate as a long-range, independent warship, with exceptional speed and large guns. Has protective metal plating on the decking as well as the sides of the hull.

Attack transport An amphibious assault vessel that carries troops and their equipment (arms and landing crafts) in an invasion force. See "Troopship".

Auxiliary cruiser A more modern (late 19th Century and onwards) name for a Navy armed merchantman, a merchant or civilian vessel armed for military purposes. Armed merchantmen of the World Wars would be classified as auxiliary cruisers as the standard term.

Auxiliary floating drydock A large portable dry dock vessel that can submerge and raise out of water in order to provide mobile repair under the water line.

Auxiliary ship A naval vessel, such as a tanker or supply ship, designed to operate in support of combatant ships and other naval operations. May also be referred to in a more specific ship type, such as an "auxiliary steamer".

Auxiliary steamer An auxiliary ship powered by steam propulsion. See "Auxiliary ship".

B

Bark A sailing vessel with three or more masts, fore-and-aft rigged on only the aftermost / mizzen mast. The other masts are square-rigged. Also spelled "barque", or "barc".

Barkentine A sailing vessel with three or more masts, square-rigged on the foremast, while fore-and-aft rigged on the remaining masts. Also spelled "barquentine".

Barracks ship An unpropelled vessel used as temporary housing for sailors.

Barrier Boat A small tug built to deploy and maintain port security booms surrounding Navy ships and installations in port.

Battleship A large, heavily armored and heavily gunned powered warship, relatively slower than other naval craft due to its armaments.

Blockade runner A merchant vessel intended to evade a blockade. Examples in American history can be seen in the Confederate States of America using blockade runners to continue commercial trade abroad and move goods to support the war effort.

Bomb brig A type of bomb vessel, which is a wooden sailing naval ship constructed as a brig (two square-rigged masts). The primary armaments were mortars mounted near the bow and elevated to a high angle, projecting their fire in a ballistic arc.

Brig A sailing vessel characterized by two square-rigged masts.

Brigantine A two-masted sailing vessel composed of a full square-rigged foremast, and fore-and-aft rigging on the mainmast. Can be further classified by specific setup, like a "hermaphrodite brig".

Broadside ironclad Earliest form of ironclad warship, with iron armor over the wooden hull and the weapons aligned on the sides of the ship.

Buoy tender See "Lighthouse tender".

C

Canal boat A type of barge watercraft, thin and narrow with a shallow draft, suited to canals and other like waterways for transporting cargo and personnel.

Cargo ship A merchant vessel that carries goods and materials between ports. May also be referred to by the more general term, a freighter.

Casemate ironclad A type of iron-armored gunboat briefly used in the American Civil War. They had a single sloped (casemate) structure on the main deck housing the entire gun battery, effective at deflecting cannon shot.

Clipper A mid-nineteenth century merchant vessel which was lightweight and designed for speed. Name derived from the Baltimore Clipper.

Coal barge A large, flat-bottomed vessel used in calm and interior waterways to transport coal.

Collier A bulk cargo ship used to transport coal.

Combat stores ship A vessel used to stow and carry supplies and other goods for naval purposes. Also referred to simply as a "storeship", or an "armed stores ship".

Corvette Traditionally the smallest class of vessel considered to be a proper (or “rated”) warship, with guns organized on a single deck. Past the age of sail, corvettes, sloops, and frigates were grouped together under the term "cruiser".

Cottonclad ram See "Cottonclad warship".

Cottonclad warship A type of steam-powered warship, used in the American Civil War, in which a wooden ship was protected by a thick lining of cotton bales and was equipped with a ram. The bales also provided breastworks lining the deck for Confederate sailors. Also referred to as a "cottonclad ram".

Cruiser A type of warship intended for high speed battle capability and cruising distant waters. Can be used to encompass the terms "frigate" and "sloop" in the transition from sail to steam and fuel power.

Cutter In the age of sail, a ship with one mast and two headsails, fast and with a shallow draft. The term may also encompass any ship in a cutter institution, like the United States Revenue Cutter Service. Mainly completes coastal guarding, survey, and convoy escort duties. Other classes utilized for long-cruises and light ice-breaking, like the Tallapoosa-class cutter. Also used in 20th Century as turbine-electric-driven sloops, such as those loaned to the United Kingdom during WWII as "Banff-class sloops".

D

Depot ship A type of auxiliary ship used for supplying and repairing small naval groups that can also be used as a floating base of operation.

Destroyer A warship designed to be fast, maneuverable, long-endurance and intended to escort larger vessels. Takes action to defend battleships and similar vessels against short range attackers, or to act as advanced scouts.

Destroyer tender A type of ship's tender or auxiliary ship intended to provide maintenance, logistics, and repair for destroyers while moored or anchored.

Dispatch boat A boat which carried messages, or mail (dispatches) between high-ranking military officials aboard other ships or to land-based destinations.

Distilling ship A class of energy-intensive military ships, generally converted tankers, with the capability to convert salt water into fresh water.

Double-ender A ship where the bow and stern are similarly constructed to look the same.

Dreadnought An early form of battleships, popular in the early 1900s and World War One, based on the revolutionary ship HMS Dreadnought. Heavily equipped with at least ten high-caliber twelve-inch guns and steam propulsion systems.

Drone aircraft catapult control ship A type of aircraft catapult designed after World War Two to specialize in the launch and recovery of early drone aircraft at sea.

E

Extreme clipper A type of clipper designed to sacrifice cargo for speed, on an already fast ship design.

F

Ferryboat A merchant vessel used to carry people, vehicles, and goods across a water.

Flagship A vessel that carries the commanding officer of a fleet, and thus flies the commanding officer's flag.

Fleet replenishment oiler A large cargo vessel with dry cargo holds and large fuel tanks used to restock ships in the rest of the fleet while at sea.

Frigate A warship that has had been designed for speed and maneuverability, ideal for patrolling, lookout, and escort duties, with fully armed spar deck. Defined in the sailing era as a three-masted vessel with all square rigs. Modern frigates, usually called cruisers, are a class of medium-speed anti-submarine vessels.

G

Guard ship A warship assigned as a stationary guard in a port or harbor, maintaining a higher degree of action readiness. This is as opposed to a coastal patrol boat, which serves its protective role at sea.

Gunboat A smaller naval warship designed to attack coastal targets, armed with one or more large naval guns. Other classes of gunboats are adapted to patrol interior waterways and to enforce the blockade, like the Unadilla-class gunboat of the American Civil War.

H

Heavy cruiser A medium sized warship, protected and armored as a cruiser, with large eight-inch guns or higher. Intended for long range and high speed objectives.

Heavy frigate A type of frigate armed with over two-dozen eighteen-pounder cannons.

Hospital ship A ship, designated or converted in emergency situations, to primarily function as a floating medical treatment facility or hospital. They have been used as field hospitals during times of war, or emergency hospitals in times of peace.

I

Icebreaker A type of auxiliary steamship of many forms (ex: gunboat) designed to plow through icy waters in the Arctic or Antarctic, able to clear the way for other ships for voyages (like research or cargo transport).

Ironclad gunboat A type of ironclad warship that is converted from or takes the specific configuration of a gunboat.

Ironclad warship A steam-propelled warship, armed with massive guns, and armored with iron and steel plates over a wooden hull ship or gunboat. Constructed from 1859 to the early 1890s, ironclad warships supplanted the wooden vessels as the most powerful warship on the coast and rivers, seen in the American Civil War with the U.S.S. Monitor and the C.S.S. Virginia. May also be referred to simply as an "ironclad".

K

Ketch A small sailing vessel with two masts (usually fore-and-aft rigged) and a square stern.

L

Light aircraft carrier An aircraft carrier smaller in capacity than full sized variants, used in World War II to fill a gap fleet allotments for carriers because they could be produced quicker and cheaper. Later converted into antisubmarine carriers and amphibious assault support.

Light cruiser A smaller to medium-sized warship, protected and armored like a cruiser, but with six-inch guns or below.

Light-draft gunboat A smaller type of gunboat, usually lightly armored, and specialized for rivers due to its low water displacement. Name may vary; draft may be replaced with "draught".

Light-draft monitor A type of monitor that had a lighter armor for a lighter draft sitting in water, like the Casco-class named after the U.S.S. Casco. Name may vary; draft may be replaced with "draught".

Lighthouse tender A ship specifically designed to support and maintain lighthouses or lightvessels by providing supplies, fuel, mail, and transportation. Accessory tasks include search and rescue, and law enforcement aid. May also be referred to as "buoy tender".

M

Merchant raider See "Armed merchantman".

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