Naval forces continue being relevant in modern military strategy, with both the Russian and American navies being engaged against relatively grounded opponents and the possibility of a future naval war being ever-present in the Pacific.

The intent of this article is to give a relatively simple overview of the terms connected to modern naval force and combat, to help give insight to a layman in what some of these words mean. If I have time and see the interest for it I will expand this concept to make overviews of other aspects of modern strategy and security policy as its own section of the blog. As this is more of a glossary than it is an article, it is not particularly exciting reading. I hope to update the blog page with some articles about modern naval policy and practice, to make this article useful.

The structure of the article is as follows: the terms are sorted into eight broader categories. Each term is given its own short paragraph, and the term explained by the paragraph is italicized. Below some of the terms, particularly the ships, there will be an image to provide a visual example.

Table of contents:

General terminology
a. Organization
b. Ships and boats
c. Armaments and sensors
d. Roles and strategies
Ship types
a. Aircraft carriers
b. Surface warships
c. Submarines
d. Support ships

1. General terminology

a. Organization

A navy is the combined maritime forces of a country, regardless of size. Some smaller countries organize their naval forces as a part of the army, if the size is deemed insufficient to make up its own military branch. Some countries organize their patrol craft in a coast guard separate from the wider navy. A navy may command ground forces, usually known as marines, or air forces, usually known as a naval air wing.

A fleet is the highest level of organization within a navy. Fleets are usually only used by large naval powers that need to cover a large geographic area. A fleet is usually assigned to a specific sea, and usually contains multiple flotillas and home ports.

A flotilla or squadron is the level of organization below fleet. The terms are somewhat interchangeable, and it varies from country to country which is used. A flotilla or squadron usually contain 4-6 vessels of the same type, and usually have a single home port.

The Russian navy consists of four permanent fleets and an independent flotilla.

A task force is a collection of warships gathered for a specific purpose or operation. Unlike fleets, squadrons and flotillas, there is no real rule to how large a task force is, and it is not a permanent organization, usually only existing as long as needed. Task forces may also be gathered from the navies of multiple countries.

A carrier battle group is a type of task force where a group of other ships follow and support an aircraft carrier.

A ship type is a name for the general role and build a ship has, such as a destroyer. These terms are somewhat standardized throughout the world, but the upper and lower size limit of warships are inconsistently defined.

A ship class is a group of ships of the same type with a largely identical build. The ship class is usually named after the lead ship (first ship built) of the class in some countries, while named after a project number in other countries.

A flagship is the leading ship of a fleet or flotilla. It is usually the largest warship in its unit, and traditionally houses the commanding officer of the fleet.

b. Ships and boats

Vessel, craft or watercraft are general terms for a water-going vehicle, regardless of size. Using the term vessel is common when speaking generally about naval equipment. Using the term craft is common when speaking non-specifically about a type of vessel that contains both ships and boats, such as patrol craft.

A ship is a larger vessel than a boat, but the difference is not sharply defined. Traditionally it is said that a ship can carry a boat, but not vice versa. Submarines are often referred to as boats regardless of size.

The Arleigh Burke destroyer USS John McCain, weighing a mere 7,000 tons, is here a boat seeing as it is carried by a ship.

A warship is a large naval vessel that can participate in naval combat. This includes aircraft carriers, surface combatants, and submarines.

A support ship is a vessel that aids the naval forces, and may be part of the navy, but does not want to participate in naval combat. An auxiliary ship is a support ship considered to exist in addition to the main naval force.

A naval ship is a vessel that is a part of a country’s navy, regardless of whether it is warship or a support ship.

The hull is the main body of a ship, carrying most of the ship’s weight and deciding the limit of its size and equipment. In naval production and construction, the hull is often used as a shorthand for ships produced. The inside of the hull will contain engine rooms, crew compartments and storage rooms. The hull is separated into multiple watertight compartments on most modern ships to make them harder to sink.

The superstructure is everything in a ship above the hull. It contains the bridge, where the ship’s command structure is located, as well as a ship’s radar systems and some weapons systems.

c. Armaments and sensors

Naval missiles are the most important type of naval weaponry. Missiles can be launched from launchers in the ship’s superstructure, or from vertical launch systems (VLS) embedded in the hull. Missiles can be designed to target surface ships, submarines or ground targets (surface-surface missile or ship-ship missile, both abbreviated SSM) or designed to target aircraft or other missiles (surface-air missiles, abbreviated SAM).

US navy ships firing a volley of VLS missiles during a naval exercise.

Torpedoes are underwater explosives that target surface ships or submarines. It is the main weaponry of most submarines, and of ships that specialize in anti-submarine warfare.

Close In Weapon Systems (CIWS) are heavy machine guns or light missiles meant to counter incoming missile attacks that have gone past allied surface-air missiles.

Deck guns are cannons used to engage targets at a closer range. Most modern warships usually only operate one such cannon, as most naval warfare occurs beyond visual range.

Directed energy weapons or lasers are still mostly experimental, but is in service with at least the US navy. The potential of the weapon is to be able to cheaply and consistently stop attacks from drones and missiles as long as the ship has power.

Sea drones are small, unmanned watercraft that travel either on the surface or slightly below it, and explode when near an enemy ship.

A Ukrainian “Sea Baby” surface drone, with which the Ukrainians have seen some success in the Black Sea.

Radar uses radio waves to find and track objects. In a naval concept, radar is used to detect enemy aircraft, missiles, and surface vessels.

Sonar uses sound waves to find and track underwater objects. Sonar is used by surface vessels or submarines to find surface vessels or submarines.

d. Roles and strategies

Naval combat entails naval forces engaging other naval forces or aircraft. Naval forces may specialize in anti-submarine (ASW), anti-surface (ASuW) or anti-air (AAW) warfare.

Power projection refers to naval forces using or threatening military force far away from their home country. This can mean patrolling a sea zone, performing shore bombardment, supporting amphibious action, or threatening such action.

A CIA map showing Soviet power projection in 1981. Naval forces activity is shown in dark blue sea zones, and communication lines on the sea is shown in purple.

Amphibious assault is the landing of ground forces, usually marines, on enemy soil using naval forces.

Sea control is the ability to keep waterways open for one’s own ships and trade, even when challenged by an adversary. In a modern context, this means both clearing the waterways of enemy naval combatants and preventing the enemy from disrupting shipping by using ship-borne air defenses.

Sea denial is the ability to keep waterways closed for an adversary’s ships without guaranteeing one’s own ability to move in the same waters. It is generally easier to maintain sea denial than sea control. Crucially, ground forces and ground-based air forces can carry out sea denial in coastal regions.

Assertion of sovereignty is when naval forces patrol their own legal or claimed territorial waters to demonstrate its country’s sovereignty and control.

Law enforcement, in a naval context, is naval or coast guard forces preventing crime at sea. This can be the fight against illegal fishing, smuggling, piracy, and so on.

Aside from practical benefits, warships carry important prestige. Warships, being the largest singular pieces of military equipment, have strong symbolic and propaganda potential. This makes some smaller countries maintain large warships in poor readiness just for the symbolism.

The Thai navy has no carrier-capable airplanes, but still purchased an aircraft carrier from Spain in the 1990s, named the Chakri Naruebet. It is currently used as a helicopter carrier, prestige carrier, and royal yacht.

2. Ship types

a. Aircraft carriers

Aircraft carriers are the largest warships in the world. They are built with a flight deck for takeoff and landing and an internal hangar for storing aircraft. Supercarriers are the very largest aircraft carriers, and nearly all of them are in service with the US navy. Most supercarriers are nuclear-powered, while most ordinary aircraft carriers are diesel-powered. Aircraft carriers are the clearest symbol of a country’s power projection ability.

The supercarrier USS Gerald R. Ford is the largest warship ever built, displacing 100,000 tons.

Helicopter carriers are smaller carriers that primarily hold helicopters. Airplanes with the capability for vertical take-off and landing (VTOL) can also operate from helicopter carriers, making the distinction between helicopter carriers and true carriers more dependent on the aircraft than the build of the ship. Most helicopter carriers have an additional role of amphibious assault ship. A Turkish and an Iranian helicopter carrier have the additional designation of drone carrier.

The Turkish aircraft carrier Anadolu was left without carrier capable airplanes after Turkey was expelled from the F-35 program. Since then, the ship has served as a helicopter carrier, drone carrier (the world’s first), amphibious assault ship and the flagship of the Turkish navy. The vertical take-off abilities of some modern fighter jets blur the line between aircraft carriers and helicopter carriers, as Anadolu will be a fully-fledged aircraft if Turkey acquires a carrier-capable fighter jet in the future.

b. Surface combatants

Surface combatants are warships armed with missiles for naval combat. They can support in power projection operations, and are entirely necessary for sea control. They are widely sorted into large surface combatants, that are capable of different combat operations and capable of navigating on open seas, and small surface combatants, that operate closer to shore and have more specialized roles.

Cruisers are the largest type of surface combatant, typically displacing around 10 000 tons. Their size is justified by an enhanced naval combat ability compared to smaller warships. Only the USA and Russia use ships designated as cruisers, but Japan and China have ships of equivalent size and capability. Cruisers are not the most numerous warship of any navy, and often have a leading role within their fleet or flotilla.

The Type 055 “Renhai” class of the Chinese navy are officially designated destroyers, but with a length of 180 meters, displacement of 11,000 tons when empty and 112 vertical launch missile cells, it has the size, power, and role of a modern cruiser. Pictured here is the third ship of the class, Dalian.

Destroyers are the second largest type of surface combatant, typically displacing 5000-10 000 tons. Destroyers typically carry multiple sets of vertically launched missiles, and are capable of engaging all types of enemy combatants effectively. Destroyers are usually the backbone of the navies of middle and great powers.

The US destroyer Arleigh Burke, lead ship of the class of the same name. She displaces 6,800 tons at a normal load, has a length of 154 meters, and carries 90 vertical launch missile cells. With 75 in service, the Arleigh Burke class is the most numerous class of destroyer in the world.

Frigates are the smallest ship type still designated a large surface combatant, typically displacing 2000-5000 tons. Large frigates may carry few vertically launched missiles, making the divide between large frigates and small destroyers especially fuzzy. Frigates tend to have the ability to engage all types of adversaries in naval combat, but not excel at it. Frigates are usually the largest ships of small countries that still want a degree of power projection capability.

The Turkish frigate Yavuz, lead ship of her class. She displaces 3,000 tons and measures 110 meters. Being a fairly typical frigate, she has no vertical launch systems, but has launchers on deck for combat against sea, air and submarines.

Corvettes are sometimes considered the smallest class of warship, typically displacing 500-1500 tons. They are usually specialized in fighting other surface warships, submarines, or aircraft with very limited abilities in the two other types of combat.

The corvette Velikiy Ustug of the Buyan-M class, part of the Russian navy’s Caspian flotilla. She displaces 850 tons and measures 75 meters. The ship class is primarily built for anti-surface warfare, with a very modest anti-air capability.

Missile boats or fast attack craft are the smallest type of combatant that can meaningfully be called a warship, typically displacing 100-500 tons. They usually only operate in coastal areas, and usually only have an anti-ship role. Fast attack craft rely on speed and small size to avoid detection and engage enemy ships on a closer range.

The Norwegian missile boat Gnist of the Skjold-class. It is the fastest class of warship in the world with a top speed of 60 knots. The ship is specialized in anti-ship warfare, and with its 273 tons displacement and 47.5 meter length it has a typical size for a missile boat or fast attack craft.

c. Submarines

Missile submarines are large submarines with the ability to launch ballistic or cruise missiles from underwater. They are often used to maintain a safe form of nuclear deterrence, as they won’t be destroyed if the mainland is attacked in a nuclear first strike. As a consequence of their size and application, missile submarines are mostly used by great or middle powers, and are usually nuclear-powered.

The Russian nuclear powered cruise missile submarine Orel of the Oscar class. With a length of 155 meters, the submarine has a size to match many large surface warships. This one is stationed in Russia’s Northern Fleet, and plays a crucial role in Russia’s nuclear deterrence.

Attack submarines are the more common type of military submarines. They are armed with torpedoes and are primarily meant to engage enemy surface vessels. Due to being hard to detect, submarines are helpful in a strategy of sea denial. Some larger attack submarines may be nuclear powered, while smaller submarines are usually diesel-electric.

The Swedish submarine Gotland, lead ship of its class, in front of the aircraft carrier Ronald Reagan, which it “sunk” during a wargame in 2005.

Midget submarines are in use by some smaller navies. They typically hold no more than one or two torpedoes, and a similarly small number of crew. They are cheap and hard to detect, but also slow and cannot stay underwater for as long as larger submarines.

A Ghadir-class midget submarine of the Iranian navy. They carry two torpedoes and seven crew, and Iran built 20 of them to support its policy of sea denial in wartime in the Persian Gulf. At the time of writing, their fates are unknown.

d. Support (or auxiliary) ships

Amphibious warfare ships are vessels with a main purpose to deploy ground forces on enemy territory. They are referred to by different names in different militaries depending on size and types of equipment carried. Amphibious warfare ships will usually carry a combination of landing craft, amphibious ground vehicles or helicopters that deploy ground forces to the shore, not embark on enemy shores themselves.

The Indonesian Landing Platform Dock Makassar can carry 354 troops and 35 infantry vehicles for amphibious operations. The ship class was designed in South Korea, but has been built in Indonesia and Peru on license, and exported to Myanmar and the Phillipines. By number of countries using them, it is the most successful Landing Platform Dock class in the modern day.

Patrol craft are ships primarily designed for asserting sovereignty in territorial forces and assist law enforcement. Patrol boats are smaller ships and usually stay close to shore, while patrol ships are seagoing and may have a similar size to a frigate. Patrol craft are usually only armed with a deck gun.

The Norwegian coast guard vessel Jan Mayen, lead ship of her class. This class of seagoing patrol ship is built for asserting sovereignty and aiding law enforcement in Norway’s large exclusive economic zone.

Mine countermeasures vessels are ships that detect and destroy sea mines. Traditionally, mine countermeasures are sorted into minesweeping (clearing a number of mines from an area) and mine-hunting (seeking out and destroying individual mines). In modern navies one ship class will often do both. To protect them from detection by mines, mine countermeasures vessels usually have a small size and reduced magnetic signature.

The German minehunter Weilheim in the Baltic Sea.

Signal craft are ships with powerful radar or sonar capabilities for its size. They don’t engage in naval combat themselves, but help locate potential enemies and communicates this to friendly forces. A variant of a signal craft is the command ship, that primarily works with passing information along between units.

The French navy signal ship Monge. The ship is specialized in tracking missile trajectories.

Logistics ships carry necessary supplies for naval or ground forces to function. A subtype is the fleet oiler, which carries fuel and has the ability to refuel other ships at sea.

A list and explanation of modern naval terminology