The Frigate
A Frigate is a warship. The term has been used for warships of severeal different sizes and roles over the past few centuries. Shown in the picture is a French La Fayette Class Frigate.
In the 18th century, the term referred to ships which were as long as a ship-of-the-line and were square-rigged on all three masts (full rigged), but were faster and with lighter armament, used for patrolling and escort. In most cases, they carried all their armament upon a single gun deck, while ships-of-the-line possessed multiple gun decks.
In the late 19th century (beginning about 1858 with the construction of prototypes by the British and French navies), the armoured frigate was a type of ironclad warship and for a time was the most powerful type of vessel afloat.
In modern navies, frigates are used to protect other warships and merchant-marine ships, especially as anti-submarine warfare (ASW) combatants for amphibious expeditionary forces, underway replenishment groups, and merchant convoys. But ship classes dubbed "frigates" have also more closely resembled corvettes, destroyers, cruisers and even battleships.
The Destroyer
In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, short-range but powerful attackers (originally torpedo boats, later submarines and aircraft). Shown in the picture is the HMS Daring, the most advanced air-defense warship in the world.
Before World War II, destroyers were light vessels without the endurance for unattended ocean operations; typically a number of destroyers and a single destroyer tender operated together. During and after the war, larger and more powerful destroyers capable of independent operation were built, particularly as cruisers ceased to be used in the 1950s and 60s.
At the dawn of the 21st Century, destroyers are the heaviest surface combatant ships in general use, with only four nations (the United States, Russia, France and Peru) operating the heavier class cruisers and none operating battleships or true battlecruisers. Modern destroyers, also known as guided missile destroyers, are equivalent in tonnage but vastly superior in firepower to cruisers of the World War II era, capable of carrying nuclear missiles.
The Aircraft Carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power great distances without having to depend on local bases for staging aircraft operations. They have evolved from wooden vessels, used to deploy balloons, into nuclear powered warships that carry dozens of fixed and rotary wing aircraft. Shown in the picture is one of the two future Queen Elizabeth Class Aircraft Carriers.
The Corvette
A corvette is a small, manoeuverable, lightly armed warship, originally smaller than a frigate and larger than a coastal patrol craft, although many recent designs resemble frigates in size and role. During the Age of Sail, corvettes were smaller than frigates and larger than sloops-of-war, usually with a single gun deck. Almost all modern navies use ships smaller than frigates for coastal duty, not all of them use the term corvette (from the French corvair) or equivalent. The rank Corvette Captain derives from the name of this type of ship. Pictured is the Corvette Magdeburg of the German Navy.
The Submarine
A submarine is a watercraft capable of independent operation below water. It differs from a submersible, which has only limited underwater capability. The term submarine most commonly refers to large manned autonomous vessels; however, historically or more casually, submarine can also refer to medium sized or smaller vessels (midget submarines, wet subs), Remotely Operated Vehicles or robots. The word submarine was originally an adjective meaning "under the sea", and so consequently other uses such as "submarine engineering" or "submarine cable" may not actually refer to submarines at all. Submarine was shortened from the term "submarine boat". Shown in the picture is the HMCS Windsor.
Submarines are referred to as "boats" for historical reasons because vessels deployed from a ship are referred to as boats. The first submarines were launched in such a manner. The English term U-boat for a German submarine comes from the German word for submarine, U-Boot, itself an abbreviation for Unterseeboot ("undersea boat").
Although experimental submarines had been built before, submarine design took off during the 19th century. Submarines were first widely used in World War I, and feature in many large navies. Military usage ranges from attacking enemy ships or submarines, aircraft carrier protection, blockade running, ballistic missile submarines as part of a nuclear strike force, reconnaissance, conventional land attack (for example using a cruise missile), and covert insertion of special forces. Civilian uses for submarines include marine science, salvage, exploration and facility inspection/maintenance. Submarines can also be specialised to a function such as search and rescue, or undersea cable repair. Submarines are also used in tourism and for academic research.
Submarines have one of the largest ranges in capabilities of any vessel, ranging from small autonomous or one or two-man vessels operating for a few hours, to vessels which can remain submerged for 6 months such as the Russian Typhoon class. Submarines can work at greater depths than are survivable or practical for human divers. Modern deep diving submarines are derived from the bathyscaphe, which in turn was an evolution of the diving bell.
Most large submarines comprise a cylindrical body with conical ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines this structure is the "sail" in American usage ("fin" in European usage). A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller (or pump jet) at the rear and various hydrodynamic control fins as well as ballast tanks. Smaller, deep diving and specialty submarines may deviate significantly from this traditional layout.
The Ballistic Missile Submarine
A ballistic missile submarine is a submarine equipped to launch ballistic missiles (SLBMs). Ballistic missile submarines are larger than any other type of submarine, in order to accommodate SLBMs such as the Russian R-29 or the American Trident. Although some early models had to surface to launch their missiles, modern vessels typically launch while submerged at keel depths, usually less than 50 meters (164 feet). Pictured is the HMS Vanguard.
Ballistic missile submarines differ in purpose from attack submarines and cruise missile submarines; while attack submarines specialise in combat with other naval vessels (including enemy submarines and merchant shipping), and cruise missile submarines are designed to attack large warships and tactical targets on land, the primary mission of the ballistic missile is nuclear deterrence. Accordingly, the mission profile of a ballistic missile submarine concentrates on remaining undetected, rather than aggressively pursuing other vessels. Ballistic missile submarines are designed for stealth, to avoid detection at all costs. They use many sound-reducing design features, such as anechoic tiles on their hull surfaces, carefully designed propulsion systems, and machinery mounted on vibration-damping mounts.
Ballistic missile submarines equipped with nuclear warheads serve as the third leg of the nuclear triad. The invisibility and mobility of submarines offer both a reliable means of deterrence against an attack (by maintaining the threat of a second strike), and a surprise first-strike capability.
The Amphibious Assault Ship
An amphibious assault ship (also referred to as an amphibious assault carrier or commando carrier) is a type of helicopter carrier employed to land and support ground forces on enemy territory by an amphibious assault. Shown in the picture is the USS Bataan.
While often resembling aircraft carriers, the role of an amphibious assault ship is fundamentally different: its aviation facilities have the primary role of hosting helicopters to support forces ashore rather than to support strike aircraft. However, they are capable of serving in the sea-control role, embarking aircraft like Harrier fighters and ASW helicopters. Most of these ships can also carry or support landing craft; such as air-cushioned landing craft or LCUs.
The largest fleet of these types is operated by the United States Navy, including the Tarawa class dating back to the 1970s and the larger Wasp class ships that debuted in 1989. Amphibious assault ships are also operated by the French Marine Nationale, the Republic of Korea Navy, the Spanish Armada Española, and the British Royal Navy.
The Cruiser
A cruiser is a large type of warship, which had its prime period from the late 19th century to the end of the Cold War. The first cruisers were intended for individual raiding and protection missions on the seas. Over the years, the nature and role of the cruiser has changed considerably, and today the cruiser has largely been replaced by destroyers in its roles. Shown in the picture is the USS Port Royal.
Historically a cruiser was not a type of ship but a warship role. Cruisers were ships—often frigates or smaller vessels—which were assigned a role largely independent from the fleet. Typically this might involve missions such as raiding enemy merchant shipping. In the late 19th century the term 'cruiser' came to mean ships designed to fulfill such a role, and from the 1890s to the 1950s a 'cruiser' was a warship larger than a destroyer but smaller than a battleship. For much of 19th century and the first half of the 20th, the cruiser was a navy's long-range "force projection" weapon, while the larger ships stayed nearer to home. Their main role was to attack enemy merchant vessels, so much so that this task came to be called cruiser warfare. Other roles included reconnaissance, and cruisers were often attached to the battlefleet. In the later 20th century, the decline of the battleship left the cruiser as the largest and most powerful surface combatant. However, the role of the cruiser increasingly became one of providing air defence for a fleet, rather than independent cruiser warfare. At the beginning of the 21st century, cruisers were the heaviest surface combatant ships in use, with only five nations (the United States, Russia, France, Italy and Peru) operating these at the time. Following the Italian Navy's 2003 decommissioning of Vittorio Veneto (550), only four nations currently operate cruisers.
The Patrol Boat
A patrol boat is a small naval vessel generally designed for coastal defense duties. Pictured is the HDMS Thetis.
There have been many designs for patrol boats. They may be operated by a nation's navy, coast guard, or 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.
They may be broadly classified as Inshore Patrol Vessels (IPVs) and Offshore Patrol Vessels (OPVs).
They are warships typically smaller in size than a corvette and can include fast attack craft, torpedo boats and missile boats, although some are as large as a frigate. The offshore patrol vessels are usually the smallest ship in a navy's fleet that are large and seaworthy enough to patrol off-shore in the open ocean. In larger militaries, such as in the United States military, offshore patrol vessels usually serve in the coast guard, but many smaller nations navies operate these type of ships.
The Minehunter
Minehunters are mine countermeasure vessels that actively detect and destroy individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines. A vessel that combines both of these roles is known as a mine countermeasures vessel (MCMV). Pictured is a Royal Norwegian Navy Oksøy-Class minehunter.
A minehunter uses an imaging sonar to detect and classify targets and then sends out divers or remotely operated vehicles to inspect and neutralise the threat, often using small charges that are detonated remotely.
As minehunters will often be operating in close proximity to mines, they are designed so as to reduce their own acoustic and magnetic signatures, two common forms of trigger for mines. For example, they are often soundproofed by mounting machinery on shock absorbers or by using quiet electrical drive and usually have a wood, glass-reinforced plastic (GRP) or non-ferrous metal hull, or are degaussed to reduce magnetic signature.
Minehunters are generally small, shallow-draught vessels, as they are often called upon to work in enclosed bodies of water such as shipping channels or harbours. As manoeuvrability in such areas is critical the Voith-Schneide cycloidal propulsor is commonly used, allowing the engine thrust to be transmitted in any direction. A number of modern vessels use catamaran hulls to provide a large, stable working platform with minimal underwater contact; this reduces draught whilst lowering acoustic transmission and reducing the fluid pressure generated by the moving hull that may otherwise detonate mines with a hydraulic pressure trigger.