Vessel Type Definitions

Aircraft Carriers

Aircraft carriers are medium to large sized ships that exist to carry and operate combat aircraft, both fixed-wing and rotary. A number of amphibious ships also carry and operate aircraft, but they do so primarily to support amphibious operations. This category of vessel type will include the following three types of aircraft carriers in operation with world navies:

• Conventional Take Off and Landing (CTOL) aircraft carriers (CV/CVN) - Currently, Brazil, France, and the United States are the only nations that operate large-deck aircraft carriers that can accommodate CTOL aircraft. A CTOL aircraft carrier requires steam catapults, an angled recovery deck, and arresting gear; features that significantly increase cost and ship size.
• Short Take Off and Vertical Landing (STOVL) aircraft carriers (CVS) - A number of nations (India, Italy, Russia, Spain, Thailand, and the United Kingdom) operate smaller aircraft carriers (generally, 11,000 to 21,000 tons, but Russia's Kiev class is considerably larger at 48,500 tons) that operate STOVL aircraft, primarily Harriers. A STOVL aircraft carrier does not require catapults, an angled recovery deck, or arresting gear, but is usually fitted with a ski jump forward to facilitate short take offs. Korea, Turkey, and Japan have also expressed interest in acquiring aircraft carriers, and may build smaller ships capable of operating STOVL aircraft. The United Kingdom will return to big-deck carrier operations with its Future Aircraft Carrier (CVF) Program, which will commission one ship in 2012, and a second in 2015. The United Kingdom is examining CTOL, STOVL, and STOBAR options for the CVF, but is believed to favor the STOVL option. China is also reportedly is developing a big-deck aircraft carrier that may enter service around 2010, but no firm information is currently available as to the type of aircraft that will operate from its deck.
• Short Take Off But Arrested Recovery (STOBAR) aircraft carriers (CV) - Russia is the only nation in the world with an aircraft carrier, Admiral Kuznetsov, that operates STOBAR aircraft. A STOBAR aircraft carrier is a compromise option; like a CTOL aircraft carrier, it is fitted with an angled recovery deck and arresting gear, but like a STOVL aircraft carrier, it has a ski jump forward and no steam catapults.

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Submarines

Submarines are extremely popular with world navies and this category of vessel type will include the following four general types:

• Ballistic Missile Nuclear-Powered Submarines (SSBNs) - SSBNs, the most powerful warships afloat, are operated by only a few of the world's nuclear powers: China, France, Russia, the United Kingdom, and the United States.
• Nuclear-Powered Attack Submarines (SSNs) - SSNs are the most capable general-purpose submarines, but only a few blue-water nations (China, France, Russia, the United Kingdom, and the United States) can currently afford to build and operate nuclear submarines. However, Brazil and India have programs in place to develop an indigenous nuclear submarine construction capability.
• General Purpose Diesel-Electric Submarine (SS) - Diesel-electric submarines are the most common submarines and are operated by a large number of the world's navies.
• Small Special Purpose Midget Submarines and Swimmer Delivery Vehicles - This would include small midget submarines such as the COSMOS type as well as dry and wet swimmer delivery vehicles.

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Cruisers (CG)

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Destroyers (DD or DDG)

A destroyer is smaller, and less capable than a cruiser, but is also capable of operating independently in a high-threat environment.  Destroyers have steadily grown in size (now 5,000 to 10,000 tons), expense (nearly US$700 million apiece) and capability. Generally, a destroyer is considered to be a ship that has all of the sensors (including a sophisticated phased-array radar), combat systems, and weapons needed to operate in a high-threat environment. A number of world navies are currently building ships that, while called frigates, more accurately represent destroyers in size and capability. Examples include the Spanish F-100, the German F-124, and the Dutch De Zeven Provincien classes (all are highly capable ships displacing over 5,000 tons and carrying phased-array radars).

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Frigates (FF or FFG)

A frigate is a medium-sized surface combatant (between 2,000 and 5,000 tons) that is either suited for one specific role (anti-submarine warfare or anti-air warfare), or has lesser all-around capabilities than a destroyer. A frigate may be less capable than a destroyer, but is still a relatively sophisticated and expensive (averaging around US$325 million apiece) platform. A frigate is generally the smallest surface combatant that can conduct extended blue-water missions in a high-threat environment.

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Corvettes (FS)

Corvettes are fast (around 25 knots or better), well-armed ships that displace between 700 and 2000 tons. A corvette is generally not intended for extended ocean-going operations, and is best suited for regional operations. Corvettes are generally the smallest platforms capable of accommodating the sensors, weapons, and combat systems needed to operate in a medium threat environment. Corvettes are sometimes referred to as light frigates (FFLs). It can be assumed that the hull design for a corvette and that of an offshore patrol vessel are very similar. The differences will be in propulsion and outfitting. Corvettes will have higher speed and therefore less endurance and range than OPV, much greater armament, and less space for provisions and habitability.

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Fast Attack Craft (FAC, also referred to as PTGs or PCGs)

FACs are small (under 700 tons), fast (over 25 knots) vessels that are intended for quick, hit-and-run strike operations within 100 miles of the coast. FACs are primarily armed for a limited anti-surface warfare (ASUW) mission. They may bristle with a number of guns, torpedoes, and surface-to-surface missiles (SSMs) and thus present a credible threat to surface ships. However, a FAC lacks the range, seakeeping qualities and defensive systems needed to operate independently for any extended length of time in a high or medium-threat environment. FACs are generally employed by nations that plan to operate them close to shore, or in the shelter of archipelagoes (e.g. the Aegean, Norwegian fjords, or the South China Sea). Generally, FAC hulls are thin and made of aluminum or steel. Because of their thin hulls, modifications are more difficult to make and life expectancy is reduced.

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Offshore Patrol Vessels (OPV)

In response to a number of environmental and economic concerns, world navies and/or coast guards developed a type of patrol vessel, the OPV, which is capable of patrolling the waters of an Exclusive Economic Zone (EEZ) for extended lengths of time. By virtue of its mission, an OPV must be relatively large (generally over 700 tons) to possess the necessary range and seakeeping characteristics needed for extended offshore patrols. The higher in latitude a Navy operates (North or South of the Equator), the larger the wave heights and therefore the larger an OPV will be. For example India operates in waters that are known for very rough conditions. Some Indian OPVs are beyond 2,000 tons displacement. An OPV is often built to commercial standards and is slower (generally around 20 knots) than its corvette and frigate cousins. However, some nations will build OPVs with space and weight margins for future weapons upgrades. These types of OPVs will generally be built to naval standards including hull and equipment shock requirements. An OPV is generally lightly armed (a medium-sized gun), but is sometimes fitted to carry surface-to-surface missiles (SSMs) or ASW equipment in wartime. Most new construction OPVs are also equipped with a helicopter deck and hangar to enhance its patrol capabilities. It can be assumed that the hull design for a corvette and that of an offshore patrol vessel are very similar. The differences will be in propulsion and outfitting for each application. Offshore patrol vessels will have slower speed, less armament, and greater space for provisions and habitability thereby allowing for greater endurance and range.

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Patrol Vessels

This vessel type category will include the following patrol vessel types:

• Patrol Boat (PBs) - Patrol Boats are smaller than OPVs and larger than PCs, thus filling the range between 100 and 700 tons. A PB is designed for multi-day patrol operations (anti-smuggling, search and rescue, coastal security, etc.) in coastal waters. A PB is often armed with a small to medium caliber gun (typically a 76mm and/or 40mm gun) and machine guns. It may also be fitted for, but not with, surface-to-surface missiles (SSMs).
• Patrol Craft (PC) - Patrol craft are small (under 100 tons) and are intended to conduct short patrols (anti-smuggling, search and rescue, harbor security, etc.) in relatively sheltered coastal waters, harbors, or rivers. Patrol craft are lightly armed (usually machine guns) and have limited range.

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Mine Countermeasures Vessels (MCMV)

An MCMV is any vessel designed to locate and neutralize naval mines. A number of ship types fall within the MCMV category:

• Mine Countermeasures Support Ship (MCS) - An MCS provides command, control, communications, and logistics support to mine warfare operations. An MCS is frequently an auxiliary-type ship, but some are also capable of operating MCM helicopters.
• Minehunting Ship (MHS) - A MHS is a ship, generally over 500 tons, that is equipped with specialized sensors (usually fitted in a remotely operated vehicle (ROV)) to locate and destroy mines. An MHS may or may not also carry the traditional mine sweeping arrays that characterize a minesweeper.
• Fleet Minesweeper (MSF) - A MSF is a ship, generally over 500 tons, that is fitted to tow sweep arrays to locate and neutralize moored and bottom mines.
• Coastal Minehunter (MHC) - A MHC is smaller than an MHS, generally under 500 tons, and is intended for operations in coastal waters.
• Coastal Minesweeper (MSC) - A MSC is smaller than an MSF, generally under 500 tons, and conducts sweep operations in coastal waters.
• Minelayer (ML) - A minelayer is designed to lay naval mines; however, it often performs additional tasks such as serving as an MCS, a training ship, or a patrol vessel.

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Amphibious Ships

Amphibious ships are ocean-going vessels that are capable of conducting amphibious operations with either embarked aircraft or amphibious landing craft. There are a number of ship types that fall within the larger category of amphibious ships:

• Amphibious Assault Ship, General Purpose (LHA) - A medium to large-sized ship (20,000 to 40,000 tons) that has a full flight deck and hangar for carrying and operating helicopters and supporting VSTOL aircraft, and a well-deck for carrying and operating embarked landing craft. The US Navy's Tarawa class is an example of a LHA.
• Amphibious Assault Ship, Multipurpose (LHD) - A medium to large-sized ship (20,000 to 40,000 tons) that has a full flight deck and hangar for carrying and operating helicopters and supporting VSTOL aircraft, and a well-deck for carrying and operating embarked landing craft. The US Navy's Wasp class is an example of a large LHD (displacing around 40,000 tons) and France’s new Mistral class is an example of a medium-sized LHD (displacing around 21,000 tons).
• Amphibious Assault Ship, Helicopter (LPH) - A medium-sized ship (approximately 20,000 tons) that has a full flight deck for carrying and operating helicopters and supporting VSTOL aircraft. The Royal Navy's Ocean class is an example of a LPH.
• Amphibious Transport, Dock (LPD) - A medium-sized ship (10,000 to 25,000 tons) that has a well-deck aft for carrying and operating embarked landing craft. An LPD also has a flight deck, usually aft over the well-deck, for operating up to five helicopters. An LPD differs from a Landing Ship, Dock (LSD) in that an LPD usually carries large numbers of troops at the expense of vehicles and cargo.
• Landing Ship, Dock (LSD) - A medium-sized ship (10,000 to 25,000 tons) that has a well-deck aft for carrying and operating embarked landing craft. An LPD also has a flight deck, usually aft over the well-deck, for operating up to five helicopters. An LSD differs from an LPD in that an LSD usually carries vehicles and cargo, while an LPD carries large numbers of troops.
• Landing Ship, Tank (LST) - A ship designed to beach and discharge personnel, vehicles, and cargo via a bow ramp system. Usually over 2,000 tons full load displacement and capable of landing over 400 metric tons of cargo.
• Landing Ship, Logistic (LSL) - Similar to an LST, but may not have a beaching capability.
• Landing Ship, Medium (LSM) - A ship designed to beach and discharge personnel, vehicles, and cargo via a bow ramp. Smaller than an LST, under 2,000 tons full load displacement and capable of landing under 400 metric tons of cargo.
• Amphibious Transport (LPA) - A ship designed to carry assault troops to the site of an amphibious operation. Troops are delivered to the beach by embarked landing craft launched via davits or cranes. An LPA is not equipped with a well-deck.
• Amphibious Cargo Ship (LKA) - A ship designed to carry vehicles and cargo to the site of an amphibious operation. The cargo is delivered to the beach by embarked landing craft launched via davits or cranes. An LKA is not equipped with a well-deck.

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Amphibious Craft

Amphibious craft are far smaller than amphibious ships, usually under 1000 tons, and are designed to beach and discharge their cargo via a bow ramp. An amphibious craft is not an ocean-going vessel, and is frequently carried in a larger amphibious ship. These types of vessels are made of steel and are easily repaired and maintained for years. Propulsion and control systems are generally the only elements that need overhaul or upgrading A wide variety of small amphibious vessels fall within the category of amphibious craft:

• Landing Craft, Assault (LCA) - An LCA is a small (under 20 tons), high-speed (up to 35 knots) vessel intended to carry a small number of troops (under 20) for quick assaults or commando-style operations. An LCA does not have a bow ramp, so troops disembark over the side or via inflatable rafts. An LCA is not usually carried by amphibious ships, but is used for short-range coastal operations.
• Landing Craft Air Cushion (LCAC) - An LCAC is a high-speed (up to 40 knots) vessel able to carry troops, vehicles, and cargo across the beach from over-the-horizon distances. LCACs can usually be carried in the well-decks of LHAs, LHDs, LPDs, and LSDs. An LCAC generally displaces around 180 tons.
• Landing Craft, Medium (LCM) - A beachable vessel capable of transporting up to 100 tons of vehicles, cargo, and personnel. An LCM can be carried by larger amphibious ships in well-decks, or as deck cargo using davits for on/offload. An LCM usually displaces around 125 tons.
• Landing Craft, Personnel (LCP) - A small (10 tons) vessel used to transport personnel and limited cargo to a beach. An LCP does not usually have a bow ramp, so troops disembark over the side or via inflatable rafts.
• Landing Craft, Tank (LCT) - A larger vessel (700 tons) that can carry heavy armored vehicles in an open deck area forward. An LCT is designed to beach and discharge troops, vehicles, and cargo onto the beach via a bow ramp. An LCT is usually too large to be embarked in an amphibious ship.
• Landing Craft, Utility (LCU) - An LCU is generally and open-topped vessel designed to beach and discharge troops, vehicles, and cargo onto the beach via a bow ramp. An LCU is not large enough to make extended ocean voyages, and can be carried in the well-decks of LHAs, LHDs, LPDs, and LSDs. An LCU usually displaces between 100 and 450 tons.
• Landing Craft, Vehicle/Personnel (LCVP) - An LCVP is a ship-transportable capable of carrying troops, cargo, and small vehicles to the beach. An LCVP usually displaces less than 25 tons.

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Auxiliaries

The Auxiliary category covers a large number of ships and small craft of various types that support naval operations. To limit the problem to a manageable scope, AMI focuses on larger ships (over 1000 tons) that are capable of ocean going operations. Some of the Auxiliary ship types that AMI covers include:

• Intelligence Collection Ship (AGI) - A ship designed to collect intelligence on foreign nations, mostly electronic intelligence, but also acoustic and electro-optical intelligence.
• Missile Range Implementation Ship (AGM) - A ship designed to collect data about domestic missile tests, and to support missile-firing trials of the ship's navy.
• Oceanographic Research Ship (AGOR) - A ship intended to gather information on the physical and biological properties of the world's oceans.
• Hydrographic Survey Ship (AGS) - A ship designed to perform bottom surveys and to process data for the creation of navigational charts. An AGS also often has the capability to perform oceanographic research functions as well.
• Cargo Ship (AK) - A cargo ship transports dry cargo in support of naval forces or forward deployed ground forces. An AK generally does not have the capability to perform underway replenishment operations.
• Oiler (AO) - An AO carries fuels to naval ships at sea and can transfer those fuels via underway replenishment operations. An AO often can carry small quantities of ammunition, cargo, and provisions as well.
• Replenishment Oiler (AOR) - An AOR, also referred to as an AOE (Fast Combat Support Ship) in the US Navy, can carry a full-range of fuels, ammunition, cargo, and provisions (dry and refrigerated) for underway replenishment operations.
• Salvage and Rescue Ship (ARS) - An ARS supports salvage, rescue, and firefighting operations.
• Submarine Rescue Ship (ASR) - An ASR is primarily designed to rescue personnel from sunken submarines, but can also perform general salvage and ocean towing functions. Most navies that operate submarine forces maintain at least one ASR.