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Useful Notes / Types of Naval Ships

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Because a battleship and a destroyer are not the same thing.

NATO has a variety of different codes it uses to designate ship types (not the same as ship classes), so we'll use them.

If you want to know how things got this way, see the History of Naval Warfare. To see the kinds of firepower used on the high seas, examine Naval Weapons.

First, a few basic notes.

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    Navies love nuclear power 

If an N is in the type designation, that means that the vessel is nuclear-powered. This is not the same as nuclear-capable, the latter meaning that it can carry nuclear weapons.

Nuclear powered ships or submarines are very useful things for a navy to have. Simply put, they don't need to be refuelled during a sortie, have enough electricity to generate their own oxygen from seawater, and are only limited by the endurance of their crew and other supplies. This allows the vessel to go more or less anywhere in the ocean and if they're a submarine stay submerged for weeks if not months on end. The appearance of the first US nuclear submarine, USS Nautilus, made most techniques for anti-submarine warfare developed during the Second World War useless, since those relied on the submarine coming to surface to recharge its batteries.

All submarines in the US Navy are nuclear powered, as are all currently-active carriers; USS Kitty Hawk was the last conventionally powered carrier in service with the USN, and was decommissioned on May 12, 2009. The crazy amount of energy generated by a carrier's two reactors (eight in the case of USS Enterprise) allow them to steam at full speed around the world indefinitely. USS Enterprise could out-accelerate all of her non-nuclear escorts despite her bulk thanks to her eight reactors. They're also very fast despite being among the largest ships in the world.

There are a couple of drawbacks to using nuclear reactors for power. One of course, is the radioactivity, although this is actually far less of a problem than it was in the past.note  Nuclear-powered vessels are also rather complicated and expensive to maintain, a problem which is only exacerbated over time through exposure to a corrosive environment.

One major operational drawback of nuclear submarines is that although their range is functionally infinite, they cannot shut down their nuclear reactors without losing all systems entirely until they start the reactor up again, which may be impossible without towing the sub back to port (emergency batteries only last so long). So the reactor system, including cooling pumps and other machinery, runs all the time. This makes nuclear submarines much noisier than diesel-electrics, by the ultra-sensitive standards of modern submarine warfare. They are incapable of true "silent running".note 


A few terms are often thrown around in reference to capital ships and their roles. A couple common ones:


In naval parlance, a "flagship" is the lead ship of a group of vessels. It is so called as it is the ship used by the commanding officer of a particular group of vessels, traditionally flying a distinctive flag. It's a temporary designation- a "flag officer" (usually an admiral) can move his or her flag as he or she sees fit. Flag officers usually choose larger ships so that there's room aboard for him/herself and the accompanying staff, which can be considerable.

Some ships may have a separate flag bridge. The regular captain still runs his or her vessel and does not have to take orders from the Admiral regarding their own ship. For example, the Admiral can tell the captain where to go, but the Captain will decide how he gets there. This will often have extra communications and data-handling facilities in order for the admiral to be able to manage the battle adequately. Depending on the class and size (and sometimes the age) of ship, these may be integral or added on afterwards at the expense of something else (e.g. some of the guns, in ex WW-2 cruisers that no longer needed as many and/or which were being converted to missile armament).

Flagships tend to be carriers, cruisers or destroyers, but specialized command vessels exist too. As expected, the United States Navy is the most active user of these, having an entire (two-ship) class of vessels, the Blue Ridge class, to serve exclusively as command ships; the ships are currently assigned to the Sixth Fleet (based in Italy, as part of USEURCOM) and the Seventh Fleet (based in Japan, as part of USPACOM).

Capital ship

The key vessels of any navy—the ones expected to do the majority of the fighting and the ones on whom victory or defeat hinges. Depending on the time period, these may be:

  • 3rd Rate (74 Guns) or better Man O' War (80 to 100 guns was 2nd Rate, 100+ guns was 1st Rate) during the Age of Sail.
  • Battleships and battlecruisers, between about 1860 and 1945.
  • Aircraft Carriers, from about 1920 onward.
  • Nuclear submarines, from about 1968 onward.

Destroyers and cruisers have historically not been considered capital ships, but due to role and size creep, may act as such in modern navies.

    "G" is for Guided Missile 

Most ship designations were created before the 1950s and 60s. Ships then were separated by size and role. Then, the guided missile was invented. The difference in range and combat power between a ship armed with conventional guns and one armed with guided missiles was such that navies around the world added "G"s into their designations so that they were still accurately divided. Therefore, a DDG is a destroyer with Guided Missiles. Likewise CG, CGN, FFG, SSG, SSGN, etc. Most vessels today have some form of guided missile, like anti-air, and often anti-ship.

For more information, see Naval Weapons.

To actually get the "G" you must have an area defence SAM with a range of more than 10 nautical miles, i.e the capability to defend other vessels. Older frigates and destroyers like the Spruance-class destroyers and Leander-class frigates never got a G despite carrying short-range SAMs and, in the case of the former, a formidable array of surface-to-surface weapons.

However, this system is at times inconsistent, with the SSGN designation going to submarines whose only air defence is likely to be a couple of dudes with hand-held SAMs standing on the conning tower or just the crew taking pot shots with rifles (or, y'know, going under the water). In the context of submarines and only submarines, the G indicates surface-to-surface guided missiles like the US Tomahawk.

    Size Creep 

Simply put, any given category of warship tends to increase in size and displacement over time.

Take destroyers, for example: when the Spanish Destructor was launched in 1887, it had a hull 192 feet long and a beam 25 feet wide, displaced around 380 tons, and a complement of 60 men. Compare this to one of the United States' current Arleigh Burke class destroyers, the largest of which have a hull 509 feet long and a beam 66 feet wide, a displacement of around 10,000 tons, and a crew consisting of 23 officers and 300 enlisted men and women. Similar figures can be seen with aircraft carriers and frigates, both of which have seen their displacements increase several times since their respective designs were first conceived. On the other hand, size of cruisers began to (temporarily) shrink shortly after World War II, as increasingly powerful anti-ship missiles were seen as rendering heavy armour and big guns obsolete. The result has been that there is no longer any actual difference between a destroyer and a cruiser. Indeed, the last cruisers commissioned by the US Navy were literally built on an identical hull to the destroyers built at the same time.

The reason why modern warships are so much larger has a lot to do with the fact that they are designed to be more effective at multitasking. Whereas the 19th century Destructor was originally designed as a fleet escort for the specific purpose of destroying torpedo boats, a modern multirole destroyer of the Arleigh Burke class can attack all manner of surface, underwater, and aerial targets at the same time. Such a design philosophy is made possible by technological factors such as miniaturization and computer networks, both of which allow the integration of multiple weapons systems inside a single hull or for a smaller vessel to take on the functions of a larger one. Additionally, improvements in engines, hull design, and material science has led to larger warships being built without the engineering limitations of their forebears.

    Designation issues 

Certain classes have been dubbed frigates when they're closer to destroyers or something like that, often for budgetary reasons or to sound less militaristic. Other reasons, as noted above, may have to do with advances in technology rendering one class of vessel obsolete while pushing new ones to the forefront. This happened in the 19th century with ships-of-the-line and frigates: although the former carried several times more guns than the latter, a combination of rifled guns firing explosive shells, steam power, and iron cladding allowed the construction of frigates more powerful and manoeuvrable than a ship-of-the-line. One also has to deal with non-English speaking navies, especially the Soviet/Russian one, who use a different set of names.

  • The British Invincible-class STOVL carriers were dubbed "through-deck cruisers" to get them through the Treasury and had a space-consuming Sea Dart SAM system built in, later removed (among other things, this enabled them to carry more aircraft).
  • Soviet/Russian carriers were dubbed "aviation cruisers" by Moscow in order to bypass restrictions on aircraft carriers passing the Bosporus. Legal shenanigans aside, however, it was a close reflection of their actual armament.
  • Japan's Hyūga class "helicopter destroyers" look suspiciously like helicopter carriers, which can generally also operate V/STOL jets. Japan's constitution prohibits an offensive military; aircraft carriers of any kind are almost always interpreted as being forbidden by this (given Japan's history with aircraft carriers, there is a reason for this). The JMSDF insists that it will only use the "destroyers" for helicopters, though no good explanation is given for why they need a long flight deck...
    • The JMSDF has commissioned a pair of even larger "helicopter destroyers", the Izumo-class. The new "destroyers" are over 800 feet long and weigh in at over 27,000 tons, making them larger than many of Japan's World War II aircraft carriers. Unlike the Hyūga class, the CIWS mountings are all on sponsons off the sides of the flight deck, meaning there is no obstacle to the operation of fixed-wing aircraft. One of the elevators is also positioned on the deck edge, just aft of the island, instead of the middle of the flight deck. Its long deck makes it very possible to operate V/STOL jets with reasonable efficiency. There is also speculation that Japan intends to employ an anti-submarine version of the V-22 Osprey tilt-rotor aircraft, which could also explain the need for such a gigantic ship instead of just building another pair of Hyūgas. In the early 2020s, Japan bought several F-35C models (capable of S/VTOL) and admitted they would be used with the larger ships.
  • The US went without a class of "cruisers" under the old US naming scheme. This was changed when the US public and Congress began to perceive a "Cruiser Gap" vs. the USSR—that is, on paper, the USSR had many more cruisers than the US, as the only ships the US called cruisers were old "gun cruisers" (CA, CL) left over from WWII and the few nuclear-powered cruisers that it had (CGN). To eliminate the "gap", the US re-categorized its ships, with the ships from the Belknap and Leahy classes designated DLG, or destroyer leader, redesignated as CG, cruiser guided missile. Destroyer leaders that were deemed too small to designate as cruisers were instead redesignated as simply guided missile destroyers (DDG). At the same time, destroyer escorts (DE) were redesignated as frigates (FF), in keeping with the designation commonly used in other navies for small escort ships. Though this caused a bit of confusion at the time, because previously the US Navy had considered destroyer leader (DL or DLG, meaning a large destroyer intended as a flagship of a destroyer flotilla) to be a term interchangeable with frigate.
  • The Ticonderoga-class cruisers were originally designated DDG, being built on the hull of the Spruance-class destroyers. This was changed to CG during construction to help slip these billion-dollar ships past Congress.
  • The US Zumwalt class "destroyers", two of which now commissioned, could easily be re-designated as cruisers (in an absurd case of size creep, the Zumwalts are larger than every light cruiser the US Navy has ever built, and most of the heavy cruisers as well). It seems to be the reverse of the "Cruiser Gap" nonsense: buying a bunch of destroyers sounds less expensive than buying the same number of cruisers. So for the benefit of Congress in an era of reduced naval budgets, the Zumwalts are "destroyers". This proved to be relatively ineffective, Congress ended up cutting the production from 32 ships to just 3.
  • The US Navy operates a wide variety of ships with spacious (sometimes full-length) flight decks and hangar decks, designed to operate a variety of aircraft to occasionally include V/STOL strike jets. That said, the US Navy has a fairly narrow definition of Aircraft Carrier (large, fast ships dedicated to the operation of aircraft, especially fixed-wing fighters and bombers), so these smaller assorted ships are designated Landing Helicopter Docks, Landing Platform Docks, and so on, often being dedicated to niche roles that carriers could do if there weren't smaller cheaper ships to fill the role. As the names imply, these ships often feature integrated boat bays, essentially hangars located below the water line, that allow the ship to easily load and unload personnel and equipment from the ship into amphibious vehicles or boats. When Marines snark about the US Navy being their own personal taxi service, these are the taxis they hitch the proverbial thumb out for.

With that out of the way, let's begin.

Types of naval ships

    Pre-steam warship types 

The majority of this article is devoted to the types of ships that are used today or were used within the last century. Some of these ships share names with, but are separate from, older ship types from the Age of Sail or earlier. Sometimes called "Men 'O War". Although they further break down into sub-types based on their particular rigging style, here is a list of warships that you might find when tall ships ruled the waves:

  • Galleys: Warships that were mainly human-powered, with rows of "sweeps" (oars) that gave them superior maneuverability compared to sailing ships and bursts of speed for short distances, but not much long-range capability. They also had to be light enough for rowers, and so didn't usually carry heavy weapons, or if they did, they carried only a few, typically in a chase armament. The oldest type of warship, they continued to be used into the 1700s in a coastal defense role. Many were designed solely for boarding or ramming. The term "galleon" derives from galleys, even though it came to generically describe large sailing ships with no oars at all. It is something of a stereotype that galleys were largely manned by slaves at the oars but this was actually only true for a relatively short period from the mid-1600s to the mid-late 1700s. Rowing a warships and manuevering in order to effectively board or ram an enemy ship is actually quite difficult, and slaves are generally not highly motivated to fight the enemies of those who enslaved them, so ancient navies relied on free, skilled mariners, each handling a single oar and joining in the ship's defense if boarded. It was only with the advent of naval guns that a slave galley became viable, as the tricky manuevering was no longer necessary; you just had to generally get the ship pointed at the enemy and let the gunners do their work. But of course, sailing vessels became dominant around the same time and so slave galleys quickly disappeared.
  • Armed Merchantmen: Before steam, big guns, and armor, almost any ship would do as a warship if it could carry guns and/or lots of extra men. Although they generally couldn't stand up to purpose-built warships, they made a suitable substitute for defending against pirates, going pirating, and as a little extra firepower when you were short on real fighting ships. Once armor and big guns became important, these gradually went away as it takes a very different design for a ship to effectively mount modern weapons vice transport cargo efficiently.
    • The concept made a brief comeback steam-era in the each of the World Wars; a key German strategy each time was attempting to choke off supplies from Britain, which as an island can only be supplied by sea. As a stopgap measure many merchant ships were given guns for self-defense and sometimes sandbags around vital areas as improvised armour. At the same time Germany armed (and disguised) its own merchant ships in order to sneak up on unsuspecting British ships and sink them before they had a chance to call for help.
  • Packets: Small, fast, lightly armed ships for transporting messages, light cargo, and small numbers of people. Cross-oceanic communications in the age before radio depended entirely on ships carrying messengers or letters, and even without crossing the ocean, often a sailing ship could make better time from port city to port city than a rider on horseback could, since it didn't have to stop and rest on the way or deal with difficult terrain. Any ship could do this job, but the side with the fastest communication had an advantage, and that it was important that the messages or passengers not be intercepted or fall into enemy hands. Thus, some navies would take the fastest ships they could find and outfit them with just enough weapons to make them unappealing targets for pirates and hard to capture for the enemy. Their captains would then be ordered to take on messages and stop for nothing else.
  • Brigs, Sloops of War, and Cutters: Single-deck ships even smaller than frigates, used in a wide variety of roles from open-sea raiding to freshwater naval battles. The development of shell guns and steam power prompted sloops of the mid-19th century to slip into a direct battle role, a notch below frigates in combat power.
  • Frigates: Smaller ships meant for long-range, independent cruising, scouting for a large fleet, commerce raiding, and one-on-one actions versus enemy frigates. A defining characteristic of frigates was that the most if not all of their armament was mounted on a single gun deck, whereas ships-of-the-line had multiple gun decks. Their lone-wolf nature leads many of the most exciting sailing stories to take place aboard these. Their role was eventually replaced by cruisers, and then submarines and aircraft.
    • Over time, frigates grew in size to be comparable in length (though rarely in height) to contemporary ships-of-the-line, with fewer guns but superior speed and manoeuvrability. The battlecruisers of their day, to an extent, but since armor didn't exist in ship design of the time it was firepower that they traded to for their speed. These "heavy frigates" also did sacrifice durability to an extent relative to ships of the line, in the sense that like all frigates their internal framing was less extensive than in a ship of the line, and didn't use as thick wood.
  • Ships-of-the-Line: Large sailing ships meant for one purpose: direct, close-range combat with the enemy fleet in the "line of battle". Slow and heavily armed, they were eventually replaced by Battleships, whose type name is a shortened version of the original phrase "line-of-battle ship". (Another modern inheritance of that phrase, used only to describe civilian ships now that the line of battle is itself obsolete, is the word "liner".) To maximize firepower, ships-of-the-line had two or even three decks of guns (or in the case of Spain's infamous Santísima Trinidad, the largest warship of the age of sail, four gun decks), though massive three-deckers proved to be rather impractical since maintaining stability required the third gun deck to be very close to the waterline and thus the gun ports had to be locked closed in all but the calmest seas.
    • The power of a ship of the line was defined by how many guns it could carry. This was normally only applied to the long-barreled cannons on the gun decks, with smaller anti-personnel swivel guns not being counted. Since Britain's Royal Navy had the most ships of the line, their "rating" system (particularly the version in use as of The Napoleonic Wars) is widely used to describe all navies' ships. A 3rd Rate ship of the line was rated for 64 to 80 guns. A 2nd Rate had 90 to 98 guns. And a 1st Rate had 100 or more guns.note  There had previously been 4th Rate with 50 to 60 guns, but starting in 1756 they were no longer considered powerful enough for the line of battle and were given the catch-all designation of "cruiser".
    • Late in the age of sail, the concept of the razee was introduced: a ship of the line cut down by removing the upper gun deck and any partial decks above it, allowing older ships of the line to extend their useful career by turning them into heavy frigates. In the rare instances where this was done to a large 3-deck ship of the line, this would also make the remaining lower gun deck much more usable since the now much lighter ship would sit much higher in the water. But the primary advantage was because ships of the line were built with significantly larger masts that flew correspondingly large sails.note  The larger sails of a razee frigate meant that it would be faster than normal frigates despite its heavier hull, and that heavier hull would be able to maintain its speed easier even in rough seas. The downside was that a razee's heavier and wider hull also made them less agile and slower to accelerate than a conventional frigate. Razees were usually built from 3rd Rate ships of the line and were designated as 4th Rate afterward.

    Aircraft carriers 

Aircraft Carriers (CV, CVA, CVS, CVAN, CVN) note 

Nothing quite beats an aircraft carrier for a) coolness and b) power projection. If a hostile carrier shows up on your coast, you are in trouble - especially a US one, as their air groups are larger and more powerful than most nations' air forces.

Only certain aircraft can take off or land on an aircraft carrier. Choppers and some fighters are fine (with modern aircraft, carrier-friendly models have to be designed to be carrier-friendly from the outset), but generally nothing bigger. This is because carriers are still small compared with air bases. Even carrier operations are fraught with problems.

  • Taking off, you will either have to take off vertically, go up a "ski jump" ramp (most non-US carriers) or be catapulted off the end (the US and French approach). The last approach means that a pilot is exposed to very high acceleration and the plane has to be built for being pulled by its nose gear as well as pushed by its engines. The advantage of a full-length carrier, however is that you can launch and recover larger, heavier aircraft carrying more and/or heavier weapons. Note before the invention of jet aircraft this was not a problem; propeller-driven aircraft before the 1950s were light enough to achieve flying lift in the short space of a carrier's deck. (Early catapults did help, however, in launching fully-loaded aircraft, or when the aircraft were launched sideways off the hangar deck...)
  • Landing, you have to find the carrier (not an easy proposition in the dark) and land on it (again, not easy considering factors like wind speed and the carrier's own movement). With an arrester wire as in US carriers, this requires actually getting in the right place to snag the wire (with an arresting hook that your plane must have), which then slows you down very quickly indeed. The whole process has been described as a "controlled crash" and also "landing on a postage stamp" and "having sex during a car accident". Then try doing it damaged. Before the invention of aircraft that could land vertically, this was the only way to get a plane aboard a ship at sea, aside from landing on the water and being hoisted aboard, something that not all aircraft were good at.
  • A notable exception to the "no large aircraft" trend occurred during the 1942 Doolittle Raid. A bunch of B-25 medium bombers were launched from an aircraft carrier to bomb Tokyo. A B-25 is of course much, much smaller than a B-52, but they were certainly never meant to take off from a carrier, and had to be significantly stripped down to be light enough to take off in the required space. The pilots also took off knowing, at best, this would be a one-way trip to China: the planes certainly couldn't land on a carrier.
  • Carrier aircraft are often designed with folding wings to make them easier to store and move around.
  • In addition to the various weight and space limitations of landing and launching from a carrier, there is the problem of corrosion. The ocean is of course made of salt water, which has very nasty corrosive effects on iron and steel (ever wonder why sailors spend so much time swabbing the decks and repainting the ship?). Maritime aircraft often have to be specially designed and equipped to be particularly corrosion resistant, an issue that land-based aircraft need not worry about.

Carriers don't carry much in the way of their own personal weaponrynote . They need other ships to protect them from attack, and also rely on their own aircraft. Their decks are generally reinforced to allow them to eat the occasional missile if absolutely needed, but a carrier generally shouldn't be in range of any surface ships, and most of their sparse weapons are dedicated to anti-aircraft roles.

As an aside, due to their design, with large hangar bays and open flight decks, it is not uncommon to see carriers serve as transports. One common wartime duty for carriers is transporting land-based aircraft to distant bases, with the aircraft often partially disassembled or packed too tightly to carry out air operations. That said, there have been occasions where land-based aircraft were ferried near their new base, then launched from the carrier to complete their voyage. Many of the carriers built during World War II were converted into transports after the war.

There are multiple different classifications of aircraft carriers, based on the role they fill and the types of aircraft they can carry and launch. Listed below are the most common categories:

Full-length carriers

Large carriers meant to operate with large fleets. They can carry larger aircraft, such as the F/A-18 and Su-33. Only five nations have one currently (US, Russia, France, China, India).

Within this category there are two major variants. The "standard" type (still used by the US and France) is CATOBARnote , which uses a steam (or in the recently commissioned Gerald R. Ford class, electromagnetic) catapult to launch aircraft and arrestor wires to catch them by a tailhook when landing. The more recent variation is a hybrid of STOVL and CATOBAR called STOBAR note (used by Russia, China and India, though the latter two plan to build CATOBAR carriers eventually), in which aircraft take off via a ski jump without catapult assistance, but land using arrestor wires. CATOBAR allows for higher takeoff weight and expends less fuel during takeoff, but STOBAR is simpler and cheaper, while still offering greater flexibility than STOVL carriers. Carriers before the 1950s had aircraft which were actually small and light enough that they could take off unassisted from the deck under their own power but still used arresting gear for landing, so they could have been called STOBAR, but the term had not yet been invented.

As an interesting note, despite their enormous size, full length carriers are also usually some of the fastest ships in a given fleet. This is partially a function of their high length-to-width ratio reducing the drag from water resistance. However, navies will outfit them with the expensive propulsion systems powerful enough to take advantage of their length because it allows for the launch of larger, heavier aircraft carrying more fuel and munitions. Every plane needs a certain amount of airspeed in order to fly, and catapults or ramps can only do so much with a given length. You can steer into the wind in order to increase the airflow over the deck, but this isn't reliable; sometimes the wind just isn't blowing. However, if your carrier can make 30 knots while fully loaded, then you can just make your own wind on demand.


  • HMS Furious: The first operational aircraft carrier, which saw use with the Royal Navy during World War I. Converted from a battlecruiser, and built before the concept of an aircraft carrier had been fully fleshed out, she originally had a hangar and flight deck forward of the superstructure, with a single 18 inch gun mounted aft. She launched the Tondern Raid, the first carrier raid in history, with seven Sopwith Camels attacking a German zeppelin base, destroying two airships and a balloon, for the loss of one plane. After the war, she was rebuilt with a full-length flush flight deck.
  • USS Langley (CV-1): The first American aircraft carrier, converted from the collier USS Jupiter. She was nicknamed "The Covered Wagon" due to her flight deck being built on top of much of the pre-existing and still exposed superstructure. She was eventually demoted from her carrier role and had much of her flight deck removed to live out the rest of her service as a seaplane tender (AV-3) once she was thoroughly obsolete as a carrier.
  • USS Ranger: The first American aircraft carrier built from the ground up as an aircraft carrier. Served primarily in the Atlantic during World War II.
  • Lexington-class: Laid down as battlecruisers, Lexington and her sister ship Saratoga were redesigned during construction to be carriers in response to the London Naval Treaty.
  • Yorktown-class: A class of three carriers that served as the primary carriers for the US Navy early in WWII. Two, Yorktown and Hornet, were lost. The sole survivor, Enterprise (CV-6), was the most decorated ship in US Navy history. She received 20 battle stars, was the first ship in the US Navy to sink an enemy warshipnote  during WWII, and was heavily involved in most of the major naval battles of the Pacific War. The Japanese mistakenly reported her sunk 3 times, leading to the nickname "The Grey Ghost", and for about 8 months in 1942-1943 she was the only operational US carrier in the Pacific, leading her crew to accurately claim that at that point it was "Enterprise vs Japan."
  • Shōkaku-class: This class of two carriers served as the primary arm of the Imperial Japanese Navy for much of World War II.
  • Illustrious-class carrier: One of the most important British warships of WWII. HMS Victorious she saw service in the Atlantic against the German battleships Bismark and Tirpitz, as well as service in the Pacific in the middle and later parts of the war. Of note is her service with the US Pacific Fleet during 1943, during a critical shortage of American flat-tops after the costly battles of 1942 which saw all of the Pacific Fleet's carriers but USS Saratoga put out of actionnote . Her radio callsign was "Robin", leading to an Urban Legend that she had been renamed USS Robin during this time.
  • USS Enterprise (CVN-65): The first nuclear-powered aircraft carrier. She was both the longest naval ship ever built, as well as the longest-continuously-serving ship in US Navy history, with 51 years of continuous naval service.
  • Nimitz-class: The largest warships in history—their air wings are larger than many nations' entire air forces. Nuclear-powered, like the Enterprise, but using 2 large reactors instead of 8 small ones.
  • Gerald R. Ford-class: An evolution of the Nimitz design. In what has become something of a whimsical tradition, each new US carrier built is a few feet longer than the previous one, so that the US Navy (and Newport News Shipbuilding) can always claim they are working on the largest warship ever built.
  • Charles de Gaulle: The only French aircraft carrier currently in service, and the only non-American nuclear-powered aircraft carrier.

STOVLnote  carriers

Smaller carriers, usually carrying Harriers or more reccently, F-35B Lightning II's, or helicopters due to having a shorter length. A cheaper alternative, owned by a few nations such as Spain, Italy and Thailand. Most STOVL carriers use a "ski jump" ramp allowing their aircraft to take off with larger payloads.


  • Invincible-class: A class of three that served the Royal Navy. Invincible and Illustrious served with distinction during The Falklands War, while Ark Royal was commissioned afterward. All were decommissioned by 2014.
  • Queen Elizabeth-class: One currently in service, with another to follow. The Royal Navy's newest class of carrier.
  • Kuznetsov-class: A class of two built for the Soviet Navy. Kuznetsov is in service with the Russian Navy, while the second went to the People's Republic of China as Liaoning. The Chinese are also building a third of the class with a modified design.

Light carrier (CVL)

A mostly obsolete classification, light carriers are, obviously, smaller than full-sized carriers, with a correspondingly smaller complement. They may or may not be lumped in with escort carriers mentioned below, but the difference is that light carriers are meant to operate with fast-moving battlegroups, while escort carriers are typically slower. The term "light carrier" is also sometimes used generally to refer to small aircraft carriers, like the STOVL carriers mentioned.

Many early aircraft carriers, while designed as fleet carriers, could later be considered light carriers due to size creep.


  • Independence-class: Served during WWII with the US Navy. As they were converted from Cleveland class light cruisers under construction, they were fairly fast and maneuverable for the type.
  • Japanese aircraft carrier Hōshō: The first commissioned ship in the world designed as an aircraft carrier from the ground up.
  • HMS Hermes (95): The world's first ship designed from the ground up as an aircraft carrier, though the aforementioned Hōshō was commissioned first.
  • The British 1942 Design Light Fleet Carrier, later known as either the Colossus or Majestic-class, which were not ready before the end of WWII, but saw service for many years afterward.

Escort carrier (CVE)

Often referred to as "baby flattops" or "jeep carriers", these carriers were similar in size to light carriers, but are much slower, making it harder for them to keep up with fast-moving fleets. Instead, they are primarily tasked with escorting convoys, protecting them from submarines and aircraft, supporting amphibious operations, working with other ships to hunt down submarines, and ferrying aircraft. They were intended to be cheap and quick to build, and were often converted from or based on civilian ship hulls. This resulted in a complete lack of armor and torpedo protection, and fewer watertight compartments than a similarly-sized purpose-built warship. Crews often joked that CVE stood for "Combustible, Vulnerable, Expendable", though ironically, since they were usually further from the front lines, they took fewer losses as a percentage than other types of carrier.


  • Long Island-class: The first escort carriers in the US Navy. These ships were built on merchant hulls and designed to be cheap and plentiful.
  • Casablanca-class: The most numerous class of aircraft carriers ever built.

Helicopter carrier (CVHA, CVHE, LHA, LHP) note 

These carriers are only supposed to carry helicopters. Those that can operate fix-winged aircraft are considered STOVL carriers. Many of their roles overlap with amphibious assault vessels.


  • The Japanese Hyuga-class.
  • Izumo-class: A class of two helicopter carriers built for the JMSDF to replace the aforementioned Hyugas. Approval was given in 2018 to convert them to be able to land F-35Bs, making them STOVL carriers in the process.
  • The Soviet Moskva-class, which were designed primarily for anti-submarine warfare.
  • Canberra-class: A class of two landing helicopter docks built for the Royal Australian Navy, based on the Spanish Juan Carlos I aircraft carrier.
  • Wasp-class: A class currently in service with the US Navy.

Aircraft/Helicopter Cruiser

This concept combines the aircraft-handling facilities of a carrier with the surface warfare capabilities of a battleship or cruiser. It was first tested in World War II. During the Cold War, various nations went on to use such ships. They aren't that common anymore, though, since the combining the different operational and structural requirements of carriers and surface combat vessels would, in the end, make them great at neither, not to mention their high cost.


  • Carriers that fly the Russian ensign use this concept in a blatant but generally accepted attempt to get around the aforementioned rule forbidding carriers from going through the Bosporus have formidable armament in their own right.
    • The Admiral Kuznetsov-class carried a large number of anti-ship and anti-air missiles. The anti-ship missiles have since been removed.
    • The Kiev-class had their entire foredeck dedicated to carrying large numbers of missiles. Four vessels were built; two have since been retired and sold to China as museums, a third was scrapped, and the fourth was sold to India and converted to a dedicated aircraft carrier.
  • During World War II, Japan converted one of its cruisers, Mogami, and its two Ise-class battleships into hybrid carriers with aircraft facilities aft. Its two Tone-class heavy cruisers were also designed with this in mind from the start, with a large aft deck for reconnaissance floatplanes.
  • The French Jeanne d'Arc.
  • The Italian Vittorio Veneto-class.

Seaplane Tender (AV)

Ships designed specifically for handling seaplanes. Some were basically an aircraft carrier with no flight deck; some didn't have the facilities to actually store aircraft and could only service or repair a few at a time. Now obsolete as no navy uses seaplanes anymore.


  • USS Langley was the US Navy's first aircraft carrier. She was later converted to a seaplane tender, and was sunk early in WWII.

There are also various ships that look like aircraft carriers, and appear to function as them to various degrees, but get designated otherwise, often due to being designed specifically for a particular type of mission or lacking certain attributes seen as necessary for a dedicated carrier. Though sometimes political considerations may be the reason.

  • Amphibious Assault Ships: Typically classified as various types of landing ships, these are too small to carry out full-out air operations (their deckspace usually dedicated to helicopters and a few V/STOL planes). They usually operate under the umbrella of a dedicated CV.
  • And sometimes you end up with weird cases such as USS Wolverine and USS Sable, possibly the only paddle-wheel freshwater aircraft carriers in naval history. Both ships were officially classified as Miscellaneous Auxiliaries rather than Aircraft Carriers, and used to train Naval Aviators in carrier operations on Lake Michigan during World War II, due to a critical shortage of CVs needed in combat. Neither ship possessed a hangar deck, and both ships were too small and slow to launch and recover planes in calm winds.


Battleships (BB)

The Big Boys. First of all, to forestall any confusion generated by poor use of terminology ("battleship" is often incorrectly used as a synonym for "warship"), there are no battleships on active duty in any navy today, after the U.S. Navy retired the Iowa-class in 2005. Until World War Two, these were the largest, most powerful warships in use. They carried the biggest guns, ranging from 9 inches (technically, 240 millimeters) to 18 inches (again, technically, 460 millimeters, or 18.1 inches…) in diameter and capable of throwing projectiles weighing a ton or more up to 35 miles, and carrying thick armor plate. Initially regarded as the dominant fighting ship, they were dethroned from that role during WWII by aircraft and submarine weapons. They were finally rendered obsolete by guided missiles, which let smaller ships carry similar amounts of firepower at a much cheaper price. They last fired their 16 inch (406 mm) guns in anger in Operation Desert Storm in 1991. At the time of their retirement they were equipped also with long range Tomahawk missiles.

They are, it must be said, far, far better-looking and more characterful than the efficient but soulless aircraft carriers—which perhaps explains their enduring appeal to enthusiasts. Or perhaps it's just more visceral. When one looks at an aircraft carrier, one sees little more than a giant flat top: the ship itself is not imposing, and indeed it is the smaller planes that it launches that do all the work, with the ship itself perhaps not even within visual range. On the other hand, there's no mistaking the silhouette of the battleship and what that silhouette means: many, many, MANY BFGs, and if you're close enough to tell they're pointed at you, then You Are Already Dead. Aside from actual ship-to-ship combat, battleships were very effective at providing fire support for amphibious operations and destroying shore positions; in WWII, U.S. battleships fought more Japanese coastal forts than Japanese ships. A seaborne artillery barrage is also more frightening than aerial assault, as it can come with little warning, adding the psychological effect.

The term is a contraction from the earlier "line-of-battle ship", meaning the ships heavy and powerful enough to serve in the line of battle during the era of Wooden Ships and Iron Men. At the time, "line-of-battle ship" was more commonly abbreviated as "ship of the line".

Historically, battleships have been divided into a few different types. Note that not all of these classifications are formal.

Pre-dreadnought battleships

Pre-dreadnought battleships refers to any battleships built from the mid-late 1880s to around 1905, when HMS Dreadnought was launched. Pre-dreadnoughts were typically equipped with a mixed battery of heavy guns and smaller secondary and intermediate guns. The large guns were typically mounted in two rotating turrets (one fore and one aft), while the smaller guns were in lightly-armed barbettes or hull-mounted casemates. For propulsion, they mainly relied on coal and triple-expansion steam engines, operating at relatively-low speeds (around 18 knots at most), though a few late models used oil when it came into use.
After the arrival of HMS Dreadnought and her revolutionary design, all battleships built before her were retroactively dubbed pre-dreadnought battleships.

Pre-dreadnoughts continued to be used even after the arrival of dreadnoughts, especially in smaller navies that couldn't build enough dreadnoughts to quickly replace them. But this was almost always in second-line capacities because no one was under any illusion that they were a match for dreadnoughts.note 

  • The ironclad turret ship HMS Devastation, while not a true pre-dreadnought (lacking steel armor and launched much earlier in 1871) is generally regarded as the prototype for them. She was the first ocean-going capital ship to entirely lack sails, and the first to mount her armament entirely above the hull rather than inside of it. The basic layout of the main guns in 2 twin turrets, 1 each forward and aft, would later be copied by nearly all pre-dreadnoughts. The only reason Devastation wasn't considered just as revolutionary for her time as Dreadnought in 1905 was that it took over a decade for navies to realize the superiority of this configuration to everything else that was being tried at the time.
  • HMS Royal Sovereign (completed 1892) is widely considered the first "true" pre-dreadnought, repeating the successful layout of Devastation but propelled by the then-new triple expansion steam engines, protected by compound armor (steel backed by iron instead of iron backed by wood) and replacing the excessively bulky turrets with open-topped barbettes. While on its face the latter seems like a step backwards by leaving the gun crews poorly protected, the "turrets" of nearly all later warships are technically "hooded barbettes", having a rotating barbette with an armored housing sitting on top of it.
  • HMS Majestic (1895) is also sometimes cited as the first pre-dreadnought, or least as fully solidifying what the type is supposed to be. The compound armor of Royal Sovereign was replaced by case-hardened Harvey steel armor, the "hooded barbette" style of turret was introduced and the guns were fired using smokeless powder (specifically cordite) rather than black powder. After Majestic, little changed about pre-dreadnought other than improvements to armor quality (Harvey steel being supplanted by Krupp armour and then Krupp cemented armour) and the addition of ever-bigger secondary gun batteries.
  • USS Texas, the first battleship to serve in the U.S. Navy, entering service in 1892. She was built in response to the Brazilian Navy's purchase of the Riachuelo, which was believed capable of laying waste to the entire U.S. Navy in open combat. The Texas and her quasi-sister ship USS Maine (designed on a similar pattern, but switching out the two BFGs for four smaller guns to fill the role of an Armored Cruiser) were both designed around battleships then in vogue with the European navies, but both were considered obsolete before entering service.[[note]]due largely to their turrets being mounted en echelon, rather than in line, causing numerous problems with firing the main battery The Maine was lost in an ultimately unexplained explosionnote  in Havana Bay, and the Texas served in the Battle of Santiago De Cuba during the Spanish-American War, helping to destroy the Spanish Atlantic Fleet as they tried to make a run for the sea.
  • The Mikasa, flagship of Tōgō Heihachirō during the Russo-Japanese War, mounted a mixed battery of guns, including four 12 inch guns in two turrets, and a mix of 3 inch and 6 inch guns in broadside arrangements. She is most famous for leading the Japanese fleet at the Battle of Tsushima Strait, where the Russian Second Pacific Squadron was intercepted and mostly destroyed in their attempt to reinforce Vladivostok (their original goal was to reinforce Port Arthur, but the harbor fell before they could complete their voyage from the Baltic Sea on the other side of the world). The Mikasa was preserved as a museum ship in 1922, and has been permanently moored at Yokosuka ever since. It is now the only remaining pre-dreadnought battleship in the world.


In 1905, the British laid down HMS Dreadnought, whose design was nothing short of revolutionary.

A review of the pre-dreadnought battleships had found their armament layout to be rather inefficient. Their secondary guns didn't really weigh enough less to justify their reduced power, and it also made aiming the guns more difficult. At the time the only way to effectively aim naval guns was to estimate the correct angle and then view the splash of the shells that missed to adjust for the next shot. Problem was, nobody could distinguish between the splashes of a main battery shell and a secondary shell at long range. Dreadnought dispensed with these problems by simply having a uniform main battery of 12-inch guns, ten of them, a then-unprecedented amount of firepower. She also used steam turbines, which allowed her to hit speeds of up to 21 knots, compared to earlier ships.

Dreadnought essentially rendered all previous battleships obsolete. Other countries soon began scrambling to build comparable warships. So, ironically, within five years, Dreadnought herself was rendered obsolete by new super-dreadnoughts, which packed even heavier guns and armor.

After World War I, the term "dreadnought" fell out of use, as all battleships from that point forward had dreadnought characteristics of some sort.


  • HMS Dreadnought, as mentioned, from the United Kingdom, which pioneered the concept.
    • In fact, other nations (e.g. the United States) were working on the same concept at the same time, and she has been called "a ship whose time had come" (DK Brown, "Warrior to Dreadnought"). And Italian naval architect Vittorio Cuniberti had presented his design for an "ideal battleship" (a fast 17,000 ton battleship armed solely with 12-inch guns, in other words very similar to Dreadnought) in 1903.note  But being first has kudos, and going from laying of keel to a ship which could steam, if not quite yet fight, in a year and a day shocked the world, and is a capital-ship building record that has never been beaten.note 
  • Japan very nearly beat Dreadnought by several months with Satsuma, but couldn't afford enough high-quality guns to outfit every turret. Only being able to manage four 12-inch guns, the remaining turrets were fitted with 12 10-inch guns. Had Japan been willing to follow Britain's example and scavenge 12-inch guns from their pre-dreadnought fleetnote , the term for battleships with a single-caliber main armament might've ended up being "Satsumas", which would provide a rather different image... Japan's follow-up design, the Kawachi class, was similarly impaired by Japan's limited finances and is sometimes described as a "semi-Dreadnought"; while all 12 guns were 12-inch in caliber, 4 of the guns were longer-barreled and more powerful.
  • The USS South Carolina was designed before the Dreadnought and the Satsuma, and had a far more efficient gun layout, being the first battleship to have all of its turrets mounted on the centerline and the first to use superfiring turrets (that is, one turret mounted to fire directly above another). This meant that despite being smaller than the Dreadnought, the South Carolina was just as well-armored and had the same 8-gun broadside. But construction was slow, and she wasn't even laid down until two weeks after the Dreadnought entered service.
  • However, both the Satsuma and the South Carolina lacked the other, less famous innovation of the Dreadnought: the use of steam turbines instead of triple-expansion steam engines. This was actually the more enduring innovation, as the concept of an all big gun armament couldn't be completely adhered to given that a battleship often had to defend itself against smaller ships. HMS Dreadnought herself ultimately was completed with a secondary armament of 27 3-inch guns to fend off the dreaded torpedo boats, and by the time of World War II battleships were invariably equipped with secondary guns designed primarily for anti-aircraft use.
  • Thanks to the slow construction of South Carolina and Japan's money problems, both the Americans and Japanese were beat to punch in fielding dreadnoughts not only by Germany but also by Brazil. This spurred a relatively little-known naval arms race in South America, since if Brazil had dreadnoughts, the other South American naval powers had to have their own. Since Brazil wanted to have dreadnoughts just for the sake of having themnote , and Argentina and Chile just to keep pace with their neighbornote , this all turned out to be just a colossal waste of money. And very nearly became an even bigger waste, had World War I not put a halt to British export of battleships; Brazil had just purchased what would've been a super-dreadnought and among the most powerful in the world, meaning Argentina and Chile would've again felt compelled to respond in kind. Fortunately, construction never even started on that ship when the outbreak of war led to Brazil's down payment being refunded.
  • Some British officials at the time lamented that since Dreadnought rendered all existing battleships obsolete, including Britain's own, this actually nullified the Royal Navy's quite large numerical advantage over any potential adversary. However, given that Britain was already demonstrably not the only nation to have come up with the idea, going first allowed them to take a head start in building dreadnoughts. Britain didn't just build the first dreadnought battleship, they built first four of them. By the time Germany had completed their first class of four dreadnoughts, Britain had built three different classes for a total of seven. All of them (even HMS Dreadnought herself) superior to their German counterparts. And by the time Germany was able to build a dreadnought that was unquestionably superior to these ships, Britain had already built the first super-dreadnought (armed with 10 13.5-inch main guns, all capable of firing broadside, whose heavier shells produced double weight of broadside that a first-generation dreadnought's 12-inch guns could manage).
  • Confusingly enough, another notable US battleship was also named USS Texas (in this case, with the hull designation BB-35). She's notable because, after serving in both World Wars, she remains the only dreadnought battleship in existence today, as a museum ship near Houston, Texas, and is appropriately nicknamed "The Last Dreadnought".

Treaty battleships

In 1922, the Washington Naval Treaty was ratified in the wake of World War I. It sought to prevent another naval arms race by placing restrictions on the number and tonnage of various warships, particularly battleships.

As such, many battleships built from 1922 to the beginning of World War II were built to abide by these restrictions (in name, if not in spirit), which forced the designers to make compromises which they might have wished to avoid given a choice. Regardless, the 1920s and 1930s saw a number of innovations in battleship design, particularly in engines, underwater protection, and aircraft, that would improve their capabilities.


  • The British Nelson and King George V-class battleships. The Nelsons were the first treaty battleships built as an allowance to let Britain have some ships on the same level as the American Colorado-class and Japanese Nagato. The two Nelsons, three Colorados, and two Nagatos would be collectively known as the Big Seven due to being the seven ships in the world permitted to carry 16-inch guns. The King George V-class would be built with a battery of 14-inch guns in an unorthodox layout of two quadruple turrets and one twin turret to comply with the limits of the Second London Naval Treaty.
  • The American North Carolina and South-Dakota-class battleships, the latter of which was considered the best treaty battleships built. One North Carolina-class ship (North Carolina) is preserved as a museum ship, while two South Dakotas (Alabama and Massachusetts) are preserved.
  • The Italian Littorio-class. One member of the class, Roma, was sunk by a German Fritz-X guided bomb, the first ship in the world to be sunk by such a weapon. While one Littorio would have been permissible under the Washington Naval Treaty, two was a flagrant violation of their 70,000 ton allowance to modernize their relatively old fleet, and three was just right out, and none of them would have been permissible under the 35,000 ton limit of the Second London Naval Treaty, which Italy declined to sign.
  • The French Richelieu-class. Like the Italian Littorios they were built to counter, one Richelieu could fit within the 70,000 ton limit France was given for modernizing their relatively old battleship fleet, but two was right out. The second ship, Jean Bart, would be the last battleship ever commissioned in 1949, following a long and troubled production that was understandably hindered by the German occupation and the aftermath of the war casting doubt on the value of even finishing her. Like the British Nelson-class and the preceding Dunkerque-class, the Richelieu-class had a gun arrangement that placed the entire main battery in front of the superstructure (in two quadruple turrets in the case of the French battleships and three triple turrets in the case of the British battleships), which reduced the weight of the ship by allowing a shorter armored citadel. The third Richelieu-class ordered and laid down, Gascogne, would have returned to a more conventional layout had she ever been finished.

Post-treaty fast battleships

As countries began rearming in the 1930s, technology improvements allowed for new features on battleships.

Many early dreadnoughts were built with relatively-low speeds due to their heavy armor and armament. A fast battleship, obviously, was capable of higher speeds, without compromising its armament and protection.

The fast battleship concept was first established in World War I, where the main method of making fast battleships was an increased length-to-beam ratio. After the war, the Washington Naval Treaty limited the construction of battleships, these designs were scrapped or toned down. New advances in technology, however, allowed for faster and faster vessels without having to increase length. And so, before and during World War II, a number of fast battleship designs were built.


  • The Iowa-class (completed 1944, after various retirements and re-commissioning of the class, were finally retired "for good" 1998-1999) from the United States, probably the best overall design of battleships built. You can still see all four of the class as museum ships; USS Missouri is at Pearl Harbor (her home port during World War II, which ended on her deck), while USS New Jersey is in the Delaware River in Camden, New Jersey (right across from Philadelphia, where she was built). USS Iowa is on display in the Port of Los Angeles at San Pedro, and USS Wisconsin is part of the Nauticus Museum Complex in Norfolk Virgina.
    • Following their 1980's refit, they also held the distinction of being some of the most heavily armed warships in history, with nine 16" guns, twelve 5" guns, 32 Tomahawk land attack missiles, 16 Harpoon anti-ship missiles, and four 20mm Phalanx CIWS guns. Ironically, while this made them ridiculously powerful surface combatants, the removal of all of the old machine guns pretty much made them irrelevant for air defense, which was one of their primary jobs in World War II. Not that those machine guns would have helped much against the aircraft the enemy would have been using in the 1980s, however. There were proposals for much more extensive refits that would also include anti-aircraft missiles and the Aegis combat system, or even replacing the rear turret with a flight deck for Harrier jets, but these were deemed too expensive. And there were also questions as to how stable the ships would be after such a conversion, which would've added quite a bit of top-weight.
  • The Yamato-class from Japan (completed 1941/1942, sunk 1944/1945) were the largest battleships ever constructed, weighing in at over 65,000 tons and thus 20,000 tons larger than the Iowa-class. They were armed with nine enormous 18.1" guns, a secondary armament of twelve (later reduced to six) 6.1" guns,note  a tertiary armament of twelve (later increased to twenty-four) 5" guns, and eventually one hundred sixty-two 25mm anti-aircraft cannons. They also had an excellent armor scheme with the thickest belt armor and thickest turret faces of any battleship ever built - although they had a serious defect in the way their torpedo protection was designed and Japanese armor was not the best quality, these flaws were mostly compensated for by the sheer size of the armor. In practice, though, they epitomized Awesome, but Impractical and accomplished little other than soaking up large numbers of bombs and torpedoes before sinking. The second ship of the class, Musashi, was sunk without ever firing a shot against an enemy warship. Yamato had slightly more luck, contributing to the sinking of two destroyers and one escort carrier in the Battle off Samar, but still ended up retreating when her commander lost his nerve due to the dogged fighting of the enemy fleet-even though Yamato herself outweighed (and outgunned) all of the enemy ships combined.
  • HMS Vanguard was both the last British battleship ever built and the last battleship launched by any countrynote , commissioned in 1946 and retired in 1960.



Cruisers were originally designed for long-range independent action. The term dates back to the age of sail when small warships (who were too fragile to be used in a major battle) were often sent on "cruises". In essence this meant roaming around in potentially hostile territory disrupting enemy trade and communications, striking targets of opportunity and just being as much of a nuisance as they possibly could. So a 'cruiser' was not a class of ship but a role a warship could fill, though some types of ship (such as frigates) were regarded at being better 'cruisers' than others. Since then cruisers have become a class of warship, today they are the largest types of ships below a carrier and the heaviest ships designed for surface-to-surface warfare.

The first ships designed as cruisers appeared in the 1870s and quickly diversified into a baffling profusion of types, ranging from small scout cruisers to huge armoured cruisers which were as big as (pre-Dreadnought) battleships.

After WWI, treaty restrictions divided cruisers between "light" and "heavy" types, with the late-war HMS Hawkins being the template for treaty definitions of the latter type. The designations were not based on size, but on armament. While from a design standpoint there were substantial differences between a pre-war armoured cruiser and a post-war heavy cruiser, and even moreso between a protected cruiser and a light cruiser,note  they generally served similar roles. By treaty definition, 8 inch guns were the maximum for a heavy cruiser, with guns larger than 6.1 inch automatically being considered "heavy." Heavy cruisers with guns smaller than 8 inch were either pre-treaty holdovers, ie the British Hawkins class with 7.5 inch (191 mm) guns, or ships from smaller navies that weren't bound by the Washington and London Naval Treaties.note  Likewise, cruisers with guns larger than 8 inch were either post-treaty ships or built by non-treaty nations. Since the types were defined solely by gun size (and notably not by number of guns), the US, Britain and Japan all dodged treaty restrictions on the number of heavy cruisers by building "light" cruisers that carried so many smaller guns that they were every bit the equal of a heavy cruiser in firepower,note  and had identical armor to their heavy cruiser counterparts.

A basic guide is below:

Armored cruiser (ACR)

An early class of cruiser which possessed a protective "belt" along the sides to protect its vitals against direct fire from shells and torpedoes, as well as deck armour to protect against shells plunging from above. Later replaced by battlecruisers as technology improved.


  • The Greek museum ship Georgios Averof, often mistaken (even in Greece) for a pre-dreadnought battleship, is actually the last remaining armored cruiser in the world. She was the Greek flagship in both World Wars, surviving because the crew disobeyed orders to scuttle her and instead fled to Alexandria when the Nazis overran Greece.

Protected cruiser (C)

A cruiser which only possessed an armored deck. They were much faster and cheaper to build than armored cruisers (prior to the advent of steam turbines this was seen as the only way to make a decently-armed cruiser that was still fast enough to be an effective scout). Saw use primarily in the late 19th century.


  • USS Olympia: Fought during the Spanish-American War. She is preserved as a museum ship today, the only surviving ship from the conflict. You can see her in Philadelphia, right across the river from USS New Jersey.
  • Russian cruiser Aurora: Fought during the Battle of Tsushima. Currently preserved as a museum ship, in Saint Petersburg, one of only two surviving vessels from Tsushima.

Unprotected cruiser

Basically, a cruiser with no armor at all. Made obsolete by later warships.

Battlecruiser (CC)

A term for very large cruisers with battleship-like armament. The original term proposed for the first battlecruisers was "Dreadnought armoured cruiser" (the idea being that they would be to armoured cruisers what the Dreadnought was to battleships), but this was considered cumbersome (and turned out to be inaccurate, as battlecruisers were an even greater increase in both capability and expense compared to armoured cruisers than Dreadnought battleships were compared to pre-Dreadnoughts, and thus were too valuable to spare for the commerce-raiding and commerce-protection missions that armoured cruisers were often assigned to) so it was shortened to battlecruiser. The new name would contribute to the very unfortunate tendency to treat battlecruisers as if they were suitable stand-ins for true battleships.

Battlecruisers had a bit of a heyday leading up to World War I. As their name suggests, they were meant to be a combination of battleship and an armoured cruiser: as fast and armored as a cruiser, but carrying the guns of a battleship; in other words, the naval equivalent of the Glass Cannon. They were (as described at the time) meant to outgun what they couldn't outrun, and outrun what they couldn't outgun; at the time, battleships had top speeds in the 20-knot range, whereas cruisers and battlecruisers could reach 28 knots at the minimum.

While good in theory, when it came to actual combat several problems rapidly appeared, primarily being that admirals tended to use them alongside their battleships due to their armament, they often didn't have enough armour to survive an encounter with their opposite numbers, as shown at the Battle of Jutland. In response, designers began piling on better armour, resulting in a ship that was basically a battleship, whilst battleships simultaneously got faster and faster (the generally accepted minimum top speed of a battleship by World War II was 28 knots; anything slower than that was a pre-Treaty holdover). By the time World War II rolled around the two types had basically merged into the "fast battleship", and the last British battlecruiser design (cancelled by the Washington Treaty) only earned the name because the corresponding battleship intended to go with it was even more heavily armed and armoured. The size creep on battleships meant also the increase on battleship waterline lengths and hence increase on their hull speeds (the longer the waterline of the vessel, the greater its attainable hull speed): also, larger hulls enabled them to carry larger machinery inside, and the machinery itself had gotten much lighter during the treaty-induced "building holiday". All of this came at the cost of...lots and lots of money. Battleships and battlecruisers were never cheap, but the fast battleship was even more expensive and even most of the major naval powers couldn't actually afford to built up their London Naval Treaty allotments.

The idea continued to persist though, on virtually all sides. The Washington Naval Treaty of 1922 limited the size and types of ship allowed in each navy; cruisers in particular were explicitly limited in size and armament, with a maximum of 8" guns and displacing 10,000 tons. Each side knew that if war broke out, they would need some type of ship to counter all these cruisers, and thus developed "cruiser killer" contingency designs for that event. Germany (under slightly different restrictions from the Treaty of Versailles, but with the same 10,000 ton limit) began building "Pocket Battleships," cruisers with 11" guns mounted and which displaced 12,000 tons, which they managed to pass of on paper as treaty-limited by claiming a 10,000 ton displacement. These really just heavy cruisers with unusually large guns, and were eventually redesignated as such by Germany. Japan conceptualized the B-65 cruiser. The United States, once the treaty expired, built and fielded the Alaska class,note  which were largely to counter the Japanese B-65 design that never actually got built. And so on and so forth. But by this time, battleships had already become almost as fast as battlecruisers (in the case of the Iowa, just as fast), and carriers could reach and sink cruisers long before a battlecruiser could get within range. So, just like battleships, battlecruisers spent the war escorting aircraft carriers and performing shore bombardment. Unfortunately, the Second World War showed that improvements in battlecruiser armor weren't good enough - both HMS Hood and the Kirishima were battlecruisers with much-improved armor protection, but even that was not enough to save them when facing modern battleships in combat - the Bismarck and the USS Washington respectively.

Of course, having such an incredibly cool name, battle cruisers appear disproportionately often in fiction. They're rarely actually seaborne, though.


  • HMS Hood: The last battlecruiser built for the Royal Navy, the only member of her class (the Admiral-class), and the largest and most powerful warship in the world for a time. There is some debate over whether she should be considered a battlecruiser or fast battleship. Sunk by German battleship Bismarck in 1941.
  • Kongō-class: A class of four Japanese battlecruisers, designed by a British engineer, the first of which was the last Japanese capital ship built outside Japan. They were reconstructed in the 1930s, and were later reclassified as fast battleships. All saw combat in World War II, and all but one were lost.
  • Only one type today gets labelled this, - the Russian Kirov (the original name of the first one)-class.note  A nuclear-powered cruiser with a very impressive armament (only aircraft carriers have more, those being contained in their air wings), it is really just a very big cruiser. Then again, to some extent so were the original battlecruisers.

Heavy cruiser (CA, CB) note 

Heavy cruisers are cruisers smaller than battlecruisers but larger than light cruisers, defined by the Washington Naval Treaty as having guns larger than 155 mm (6.1 inches) in caliber (usually 8 inch, or on rare occasions- such as in the case of the unique Alaska class "large cruisers", larger). Their heavier armament and armor would allow them to play more significant roles than their smaller counterparts.


  • The American Portland-class, Northampton, and New Orleans-class. Their Alaska-class "large cruisers" were the largest heavy cruisers ever built, sometimes arguably considered battlecruisers. The last surviving heavy cruiser in the world, USS Salem, is a postwar Des Moines-class and is preserved as a museum ship in Quincy, Massaschussets.
  • The German Admiral Hipper and Deutschland-class. The latter were often considered "pocket battleships" due to their disproportionately heavy armament for their weight.
  • The Japanese Myoko, Takao, Aoba, Furutaka, and Tone-classes. The Mogamis were also considered heavy cruisers after their reconstruction.

Light cruiser (CL, CLAA) note 

A contraction of "light armored cruiser", light cruisers are fully armored like armored cruisers, but much smaller, and typically armed with smaller guns, almost always 6 to 6.1 inch (152 to 155 mm) main guns but sometimes in the 5.5 inch (140 mm) range. Throughout their history, they served primarily as escorts, scouts, and support vessels.

The US and Britain also produced specialized anti-aircraft cruisers (CLAA), with very large numbers of 4.7 inch (120 mm), 5 inch (127 mm) or 5.25 inch (133 mm) dual-purpose guns as their main armament, specifically for air defense. These ships were effectively giant destroyers but with (barely) cruiser-level armor, making them an early example of the eventual overlap of the cruiser and destroyer roles. To say nothing of overlap between cruiser and destroyer design, as the CLAA basically amounted to an oversized destroyer with a little bit of armor added. They saw service through WWII, with a few more hanging on for a few more years afterward.


  • The American Atlanta class, anti-aircraft light cruisers fielded during WW2 with a total of 16 5-inch guns. Capable of putting out prodigious amounts of anti-aircraft fire, though their light armor was disadvantageous versus heavier warships. With one exception: the Atlanta class were the only American cruisers in World War II that still carried torpedoes, which proved useful in early night battles, before the wide-scale use of radar allowed cruisers to use their guns at maximum range even in poor visibility.
  • The American Cleveland-class, the most-produced light cruiser class. One example remains as a museum ship, USS Little Rock, although she was converted into a Guided Missile Cruiser in the 1950s.
  • The American Brooklyn-class. One member, USS Phoenix, was transferred to Argentina and renamed ARA General Belgrano, and would dully become the first (and so far, only) ship to be sunk by a nuclear submarine during the Falklands War.
  • The British Dido-class anti-aircraft cruiser from World War II.
  • The British "Town" class, also from World War II. One of these, HMS Belfast is a museum ship in London.
  • The Dutch De Zeven Provinciën-class cruisers. One member, the Peruvian BAP Almirante Grau, was the last gun cruiser in active service in the world before her retirement in 2017.
  • The Japanese Mogami-class were considered light cruisers, before being reconstructed and reclassified as heavy cruisers.

Scout cruiser

Scout cruisers were early cruisers that were smaller, faster, and lighter-armed than light cruisers, but larger than destroyers. As their name implied, they were mostly used for scouting, or as flotilla leaders.

They became obsolete after WWI, when technological developments allowed destroyers and light cruisers allowed them to catch up in terms of speed and armament.


  • The Royal Navy built a number of scout cruiser classes, many of which served in WWI.
  • Italy was also a fan of the concept, building a large number of them. Most were later reclassified as destroyers.
  • The American Omaha class were designed as scout cruisers, but they were later modified and redesignated as light cruisers.

Guided missile cruiser (CG, CGN) note 

Gun armed cruisers slowly disappeared after WWII. Today, cruisers are mainly armed with missiles and used as escorts for carriers, in the air defense role. The Aegis system, fitted on a number of types of cruisers and destroyers, is the USA's primary carrier protection system- an automated SAM system, for destroying anti-ship missiles. It allows for co-operative engagement- one ship can control the missiles of the others, and of other ships in the fleet whose missiles are compatible, reducing the number of radars that an anti-radar missile can home in on. Designed during the Cold War, it was not combat-proven until the Gulf War of 1991.


  • Only two nations today, the US and Russia, have actual cruisers in operational service. China is building several Type 055 class (NATO Reporting Name: "Renhai"), a 13,000 ton ship which is designated as destroyer by PLAN but as cruiser (CG) by the US (despite the US Navy's own 14,000 ton Zumwalt class being designated destroyers). They carry anti-ship and/or land-attack missiles,
  • The best-known today and the most numerous is the US Ticonderoga class, a Guided Missile Cruiser. The original Aegis ships, they set the standards for modern air defense by which all other cruisers and destroyers are judged. Starting with the sixth ship, they are armed with a pair of 64-cell vertical launch tubes for their missiles (primarily from the "Standard" family of anti-aircraft missiles, but Tomahawk cruise missiles and VL-ASROC anti-submarine missiles can be mixed in as well). The first five had old-style twin-arm missile launchers that could only fire Standard-MR and ASROC, and as a result were retired early. They were built on a slightly modified version of the Spruance class destroyers' hull (side-by-side comparison here), but with a completely new superstructure containing the Aegis system's SPY-1 phased-array radar (consisting of four distinctive flat-panel octagonal arrays, each covering one 90-degree angle around the ship) and its fire control system. Packing that much extra weight onto the Spruance design (they're 23% heavier than their Spruance predecessors) proved to put quite bit more stress on the hull than expected, but they've nonetheless held up through over 30 years of active service. One example, the USS Vincennes, infamously shot down an Iranian passenger jet during the Iran–Iraq War, having mistaken it for Iranian Air Force fighter.
  • The Russian Slava class. Notable for having its long-range anti-ship missiles mounted in very prominent above-deck launchers along the sides of its superstructure. Two are currently in service. A third, Moskva, sank on April 14, 2022 after being hit by R-360 Neptune missiles during Russia's invasion of Ukraine, the biggest wartime loss of a warship since World War II.


There are things called or formerly called "helicopter cruisers", "aviation cruisers" or "through-deck" cruisers which are basically other terms for aircraft carriers when you want to get them through the Dardanelles (an international treaty bans aircraft carriers, defining them as ships solely designed to launch aircraft - so the Soviets added a lot of missiles on) or your own country's Treasury. Although in some cases, a "helicopter cruiser" will be an actual cruiser, except with a very large helicopter hanger and flight deck.


Destroyers (DD, DDG, DDR, DL, DLG)note 

The largest ship type in many navies today or the backbone of larger navies, destroyers are (usually) smaller than cruisers, but (usually) larger than frigates, tasked with protecting larger ships (like cruisers and aircraft carriers) from submarine or surface attack. Some navies, such as the UK's Royal Navy, call warships "destroyers" if they are mainly designed to defend against air attacks, and "frigates" if they are mainly designed to fight against other ships and hunt and kill submarines. Thus, the Royal Navy's Type 42 destroyers were actually smaller than their Type 22 frigates and the Type 45s may be about the same size as the next RN frigates. Other navies divide destroyers and frigates by size rather than role, so they may have both sub-hunting and air-defense destroyers.

Destroyers were so named because they were originally "torpedo-boat destroyers", a class invented by the British in the late 1800s and early 1900s to protect battleships against small, fast, maneuverable torpedo boats. Especially with the advent of the all-big-gun "Dreadnought"-class battleships, the big ships' guns were too big, too long-ranged, and too slow-firing to adequately defend against small, fast-moving targets at close range, so destroyers were invented to fill that need. With those early destroyers, it was found that the simplest design for destroying torpedo boats was, essentially, a giant torpedo boat. Starting with WW1, torpedo boats were eclipsed as a threat by submarines,note  and so during both world wars, destroyers mostly were used to hunt submarines, defend convoys, and (starting in WW2) provide radar and anti-aircraft coverage for larger ships.note 

After WWII, destroyers began getting larger to fill in the roles left open by the phasing out of larger ships. Experiments by the US Navy led to the development of the destroyer leader, essentially large destroyers with experimental propulsion features. The term was later retired, with all destroyer leaders redesignated as regular destroyers.

It could be argued that the role of Destroyers never changed, the only question being what any given set of Destroyers was designed to destroy, be it torpedo boats, submarines, enemy aircraft, or, with modern destroyers, enemy ships, plus all the above categories. The advent of radar and guided missiles certainly gave modern ship designers much more flexibility and precision in how to apply their firepower.

Will generally have at least one helicopter on board for sub hunting, search and rescue, and general utility.


  • The American Arleigh Burke class of destroyers use a similar Aegis system to the Ticonderoga class cruisers, and are practically small cruisers. Japan operates the very similar Kongou and Atago classes as their most powerful warship type. South Korea operates the King Sejong the Great class, a slightly enlarged version with 25% more missile capacity and other less significant improvements. All are mainly designed to provide air defense with guided missiles note , although the American ships can also launch large numbers of Tomahawk land-attack cruise missiles. The Japanese versions could do so as well, except that Tomahawks (even the anti-ship version) are deemed to be prohibited "offensive" weapons and thus the JMSDF doesn't have any. The Korean ships instead use the domestically-designed Hyunmoo-3C cruise missiles (which are similar in capability but look like giant versions of the Harpoon antiship missile). Both can engage surface warships and do surface bombardment, as well. With 68 in service and at least 21 more in construction or planned (plus the Japanese and Korean derivatives for another 9 ships), the Arleigh Burkes are the most numerous destroyer class since the WW2-era Fletchers.
  • The American Zumwalt class of destroyers, currently under construction, will take the ultimate prize in size creep. They are 5000 tons heavier than the Ticonderoga class cruisers, the only cruisers left in US service, and will be armed with a pair of advanced 155mm (6.1-inch) guns, the largest (though only by one inch) to be mounted on any ship in decades (and, later on, the possibility of using railguns and lasers). If the Washington and London Naval Treaties of the 20s and 30s were still in effect, it would have been a legal requirement to designate the Zumwalt class as cruisers, and if so designated would be either the 2nd or 3rd largest cruisers ever deployed by the US Navy (depending on whether the oddball Alaska class are considered cruisers or battlecruisers). They also incorporate extensive stealth technology, rendering them perhaps the ugliest (or coolest, most futuristic looking) warships since the days of the first ironclads.note  As a result of all this, they are also incredibly expensive, and the US Navy's order for them was progressively cut down from 32 to two as cost overruns kept piling up; the Navy has since changed its mind, increasing its order again—to three ships. Ironically, the namesake of the class was an admiral who championed the idea of the Navy using a large number of smaller, less expensive ships.
    • The proposed new Russian class is also in the 12-14 kt range, and with its 2×2 152 mm cannons would certainly outgun the Zumwalts. It also could be a first nuclear "destroyer" in the world, if the nuclear powerplant will be approved for it.
  • The American Spruance class used to provide ASW for carrier battle groups. With 31 built, they were the largest destroyer class of the Cold War era. They were also the largest destroyers of that era in terms of tonnage, being similar in size to a pre-WW2 light cruiser. Their hull design was even reused for the Ticonderoga class cruisers.
    • The air defense variant, the four-ship Kidd class, was designed for the fledgling Iranian Navy (under the preliminary name of Kouroush class), but a year after construction started the Iranian Revolution happened and they instead became part of the US Navy.note  They tended to get deployed to the Middle East a lot, because one of the modifications made to the design was heavily improved air conditioning. They've since been transferred to Taiwan, being renamed yet again as the Kee Lung class.
  • The American Fletcher class, built for World War II, and the most numerous class of destroyer built. (175 total for the US Navy) Many were sold to other countries, and the last one in service was decommissioned from the Mexican Navy in 2001.
    • The Allen M. Sumner class (58 ships), Robert H. Smith class (12 ships, a minelaying subclass of the Sumner) and Gearing class (98 ships) destroyers were all closely related, with only slight changes in the hull design but a superior armament with much more efficient layout (replacing the Flechers' 5 5-inch guns in single turrets with 6 guns in twin turrets). Due to their improved layout and slightly larger hulls, some of these remained in US service into the late 1970s to early 1980s, with the torpedo tubes being replaced by an ASROC launcher and the rear turret with a hanger for an armed drone helicopter in the 1950s. As with the Fletchers, many of these were sold to other nations, and the last was retired by the Mexican Navy in 2014, after a combined 70 years of service. 4 Fletcher, 2 Sumner and 5 Gearing class destroyers survive as museum ships.
  • The Russian Udaloy class destroyersnote  are a good example of a destroyer mainly designed to hunt submarines. Roughly the Soviet equivalent of the Spruance class. While their armament also includes modern anti-aircraft missiles, they're short ranged and suitable only for self-defense.
    • The improved Udaloy II type was intended to combine the Udaloys' anti-submarine capability with the Sovremmeny class's anti-ship missiles, but only one was built before the collapse of the Soviet Union and the accompanying collapse in military funding.
  • The Russian Sovremmeny class destroyers are a good example of a destroyer mainly designed to fight other ships (with long-range anti-ship missiles) and provide air defense. China also operates 4 of them. Despite being very similar in size and introduced around the same time, they're not closely related in design to the Udaloy class and in an example of pointless inefficiency do not use the same hull design. Roughly equivalent to the Kidd class, but a lot more numerous. While most of the Russian Sovremmenys are either retired on in reserve, the Chinese quartet are undergoing a major refit with their latest weapons and sensors.
  • The Russian Kashin Mod class destroyers were used during the Cold War as "Tattletales", intended to closely follow US carrier battle groups and report back on their activities. In the event of war, they were to turn and run away, while firing backwards-facing missiles in a last-ditch attempt to sink the carrier. Everyone involved freely admitted that this was likely a futile suicide mission if war ever broke out. So, of course, just before the Cold War ended, one was sold to Poland to become the flagship of the Polish Navy. Renamed Warszawa, it was in service until 2003. The Russian Navy still operates one ship of this class, and the Indian Navy has five of the similar Rajput class (nicknamed "Kashin II" in the West), which have their missiles pointed forward.
  • The British Type 42 or Sheffield class (all named after British towns) are designed to provide anti-aircraft missile protection for British aircraft carriers. They are fairly small for destroyers (at least by modern standards), and are also operated by Argentina. Amusingly, they fought on both sides of the Falklands War.
  • The newest British destroyer class is the Type 45 or Daring class, also meant for air defence, with stealth features and a lot of weapons that it can carry, but will be left off unless needed.note  A planned twelve examples will now be six.
  • Perhaps one of the most defining of all Destroyer classes was the WWII Tribal-Class. Originally designed as Light Cruisers but instead the designs were changed to create a class of destroyers that served the Royal and Commonwealth navies with great distinction in all naval theaters of World War II. Suffering heavy losses in the line of duty, only 1 now remains, the HMCS Haida.
  • The ancestors of the modern destroyer were the Japanese Fubuki class (also known as "Special Type destroyers, as they were such a huge leap in capability over what came before them), which were the best destroyers of the late 1920s and pretty much sent the destroyer along its evolutionary path to being the formidable, all-purpose vessel that is today. Very fast, well armed and packing a devastating set of torpedoes, the Fubukis did their job in WWII, even if they were starting to get old.
  • The Akizuki class were the next major step, being twice the size of the Fubukis and nearly 50% larger even than their American contemporaries like the Fletcher classes, and despite predating the existence of missiles they were the first destroyers to be specialized anti-aircraft escorts.


Frigates (FF, FFG)note 

Frigates are generally smaller than destroyers (though the distinction is becoming less and less relevant as size creep sets in), and are almost always tasked with escort or patrol duties. "Frigate" in the modern sense is a term that only dates to the 1940s, when it was reintroduced by the Royal Navy for sub-hunting vessels. The original "Guided Missile Frigates" were later re-classified as cruisers, but the term stuck.

Frigates today are one of the most common classes of warships, and the largest ships in many navies. Their (relatively) low construction and operating costs, combined with their flexible and balanced capabilities, allow them to fill many different roles.

In some navies, "destroyer" has come to refer solely to guided missile destroyers, and thus anti-submarine escorts will inherently be "frigates" regardless of size. A prominent example is Britain's Royal Navy.

Not to be confused with the original use of the term "Frigate", which was a smaller warship from the Age of Sail; see above in "Pre-steam ship types" for a description of those.


  • The American Oliver Hazard Perry class frigates, while designed mainly to hunt subs, do carry an impressive anti-aircraft missile system for their size (their anti-submarine weaponry is primarily their helicopters), and have been exported widely. They are used by, among others, Spain, Taiwan, Turkey, Greece, Egypt, Bahrain, Poland and Australia, with some of these navies using ex-US ships and others having had Perry class frigates built specifically for them back when the design was new. Some of those ships were built in their operating country to slightly modified design, others sold off after the US Navy decided they didn't need them any more. Ironically, the anti-aircraft missiles were removed from the US examples well before their retirement from US service, due to the company making the missiles no longer offering tech support for them, and the newer versions of the missile being physically incompatible with the Perry class's older launchers. Some countries, such as Australia, decided to actually upgrade the launchers to take new missiles instead.
  • British Type 23 or Duke (they are named after English dukes) class frigates are actually larger than Type 42 destroyers, designed mainly to hunt subs, and featured in the James Bond movie "Tomorrow Never Dies". They utilize the excellent "Sea Wolf" anti-aircraft missile for self-defense; while its range is far too short to be much use in protecting other ships, it's so accurate that it can even shoot a target as small as a 4.5" artillery shell out of the air.
  • The French-designed La Fayette are frigates designed with stealth elements to minimize their radar signature. They are used by France, with variants used by Singapore, Saudi Arabia, and Taiwan.
  • Russian project 11356 frigates, an evolution of the venerable proj. 1135 Krivak class, now fielded by India as Talwar class and by Russia itself as Admiral Grigorovich class. Based on a tried and true hull design, they feature an entirely new armament (including the supersonic Brahmos/Onyx ASM), sensor and electronic packages, and the redesigned, more stealthy superstructure, which makes them pretty formidable combatants.
  • Another Russian frigate, a proj. 22350 Admiral Gorshkov, is intended to be the replacement of the Krivaks, and the latest in the gee-whiz category, with everything in the ship being state-of-the-art. Which, unfortunately, is responsible for the lead ship still not being commissioned despite standing virtually completed for a couple of years now, while all the kinks and delays in her machinery are being ironed out. At ~5 kt displacement the ship is essentially a small destroyer, and should become one of the most powerful frigates in the world when finally commissioned. However, after the delays first surfaced, the Russian Navy ordered six Grigoroviches as a stop-gap, so they might even outpace Gorshkov in the pipeline.



Smaller versions of frigates, primarily designed for coastal duties- many are now close to frigate size though. Small, manoeuverable and generally lightly-armed. Often found in navies of countries bordering smaller seas. Some smaller navies bordering major oceans will use them for heavier duty however, and typically modify them accordingly. They are usually found escorting other ships, or as patrol vessels. Corvettes are usually the smallest type of warship able to carry helicopters.


  • The US Littoral Combat Ship (LCS) is similar to a corvette; however, the U.S. Navy has stubbornly refused to use the "corvette" designation for any of its ships, even before a certain sports car came around. Even though given their 45 knot top speed is exceptionally fast for any type of warship, sharing the name of a sports car really would've been appropriate.
    • In early 2015, the US Navy actually decided to re-designate these ships as frigates and plans to arm them heavily enough to qualify. It helps they're already close to the same size as the average frigate.
  • The British Flower-class corvette saw heavy use in World War II, guarding convoys from U-boats.
  • The Swedish Visby-class corvettes.
  • The Russian Project 1234 Ovod (Gadfly) Nanuchka class.
  • The new Russian Stereguschiy class is unusual in that it manages to squeeze an integral helicopter (with a hangar etc., not just a helipad) in just 2.5 kilotons of displacement. And as usual with the Russian ships, it is armed heavier that the many frigatesnote  — which led to the habitability of the crew suffering as a result. They miss the Saar 5 armament density, though, but only because they're more then a full kiloton heavier.
  • The Israeli Sa'ar 5 class corvettes, like their Sa'ar 4.5 missile boats (see below) stretch the limit of how heavily armed a ship of their size can be. They carry 8 Harpoon anti-ship missiles, 64 Barak anti-aircraft missiles, a Phalanx CIWS, 6 anti-submarine torpedo tubes and a Panther anti-submarine helicopter. They squeeze armament similar to a full-sized frigate into a package of only 1200 tons, and at 33 knots top speed they're faster than most full-sized frigates to boot.

    Escort vessels 

Escort vessels

This category covers other ships designed specifically for escort duty. In general, this means a ship with just enough armament to counter the likely threats to a convoy of cargo ships, historically submarines and aircraft, and a long enough range to follow the convoy all or most of the way to its destination without stopping. However, they also have to be inexpensive enough to produce in mass quantities, as you need enough to cover all your convoys, and in a trans-oceanic war, there are likely to be a lot. Usually keeping the price down meant that they were small, had little-to-no armor, and were slow for warships, as the merchants they needed to escort were quite slow themselves. In most modern navies, Frigates serve this role, in addition to their fleet defense duties.

Destroyer/Ocean escort (DE, DEG) note 

During World War II, the United States Navy designated their dedicated escort vessels as destroyer escorts. These ships were smaller than and slower than true destroyers, but cheaper and quicker to build, and optimized for anti-submarine warfare. They could accompany destroyers on missions to hunt down submarines, or form the outer ring of defense for a convoy. A few other nations also operated their own versions of this concept.

Ocean escorts were the post-WWII successors to the US Navy's destroyer escorts, filling a similar role, but with more-advanced engines and propulsion. DE ocean escorts were intended for anti-submarine warfare, while DEG ocean escorts were anti-aircraft.

In 1975, the US Navy redesignated all remaining destroyer and ocean escorts as frigates.


  • The US Edsall and Cannon-classes.
    • The Dealey, Garcia and Knox-classes were postwar ocean escorts.
  • Perhaps the most famous destroyer escorts in history were the 3 DEs of Taffy 3, assigned to the defense of the US landing force off the island of Samar during the battle of Leyte Gulf in 1944. Due to a series of miscommunications and tactical errors, the landing force wound up abandoned by the powerful 3rd Fleet, and the group of unarmed landing ships and small escort carriers (CVEs) was suddenly set upon by the powerful Japanese Center Force, which included multiple battleships and heavy cruisers, including the Yamato, the largest battleship ever constructed, who outweighed every single one of her opponents put together. The only thing between the landing force and destruction was the 3 destroyers and 3 destroyer escorts of the Taffy 3 escort force. Most ships of that size encountering a battle fleet would flee; they instead decided to charge the Japanese fleet to buy time. In particular, USS Samuel B. Roberts (DE-413) became known as "The Destroyer Escort that fought like a battleship", managing to torpedo one heavy cruiser and disable two others, expending all of her 5" gun ammunition, before being sunk by fire from multiple cruisers, destroyers, and battleships. In the confusion of being attacked by ships that should have run, the Japanese retreated with significant losses.
  • The British equivalent (aside from American-build DEs provided under Lend-Lease) were the Hunt-class escort destroyers. Which were really actually four different classes, but the Royal Navy arbitrarily deemed them "types" within one class. A total of 86 were built (20 Type I, 36 Type II, 28 Type III and 2 Type IV), of which 23 were sunk. 72 served in the Royal Navy while the remaining 14 were given out to the "Free" navies of Britain's conquered allies. Post-WW2 a dozen were surplused out to minor navies as Britain no longer had any use for them. A Type I Hunt class HMS Mendip, after being sold to Egypt and renamed Ibrahim el-Awal, holds the dubious distinction of being the last warship ever to be captured in battle. After a running battle with a pair of Israeli destroyers, she surrendered on 31 October 1956 and was added to the Israeli Navy as INS Haifa.


Kaibōkan (in English, "sea defense ship", or "escort vessel") was the Imperial Japanese Navy's designation for small warships intended for coastal patrol and escort duties. Several different classes existed.


Sloop-of-war was the British designation for small vessels designed for escorting and defending convoys. After World War II, they have mostly been reclassified or supplanted by corvettes and frigates.


  • The British Black Swan-class sloop.

Submarine chaser (PC, SC) note 

Subchasers, as their names imply, are escort vessels specifically tasked with anti-submarine warfare. They are primarily armed with depth charges, with a few anti-aircraft and light guns for self-defense. Nowadays, they have mostly been replaced by frigates, corvettes, and destroyers.

    Patrol vessels 

Patrol vessels (PC, PCF, PB, PBR) note 

These vessels are designed for coastal defense, patrol, law enforcement, and/or search and rescue operations. Certain highly-specialized PBs are also used for special operations. They can be operated by a country's navy, coast guard, law enforcement, or customs agency. They are generally split into two types: Inshore Patrol Vessels, (often labeled PB for Patrol Boat) which may be relatively small and limited to coastal/riverine areas in view of the shore, or Offshore Patrol Vessels (Often labeled PC for Patrol Craft or Patrol Ship), which are quite large and capable of operating in the open ocean.

They are typically lightly-armed, if they carry weapons at all, usually with a single heavy gun or autocannon, possibly a CIWS gun, a few crew-served weapons, and/or small arms, though some larger vessels may also carry missiles and torpedoes. Some can even carry smaller boats and/or helicopters (or at least have a helipad).

Because they are inexpensive, many navies who do not have a strong oceangoing presence will have a large number of these as their primary combatant forces. Also, they are popular with navies who have long, irregular coastlines, large numbers of islands, and/or lots of shallow waters, as these conditions greatly increase their combat power and survivability against larger ships at a fraction of the cost.


  • The US Cyclone class PCs are offshore patrol vessels.
  • The US Mk VI PBs are designed for more inshore duties.
  • The US Mk V Special Operations Craft is a well known patrol boat designed and used specifically for insertion, extraction, and support of special forces.
  • The United States Coast Guard calls its patrol boats "cutters". They range in size and role from frigate-sized ocean-going near-warships to small, open topped boats for law enforcement.
  • The Australian Armidale Class PCs.
  • The US PCFs, also known as "Swift Boats", were coastal patrol boats used to stop the movement of supplies and people to the Viet Cong in South Vietnam via sea.
  • The US PBRs were riverine patrol boats used to stop the movement of enemy supplies and personnel in the rivers and deltas of South Vietnam, and occasionally for attack and support of special forces.

Gunboats (PG, PR) note 

Dedicated gunboats are relatively heavily armed boats typically meant for fire support of troops in coastal or riverine environments. Generally they traded speed for armament and maneuverability in shallow water.

  • The US Asiatic Squadron and later Asiatic Fleet operated a group of River Gunboats on the Yangtze River in China to protect US commercial interests there. Similar fleets were operated by the Germans, British, Japanese, and other colonial powers.

    Fast attack craft 

Fast Attack Craft (FAC)

Eggshells armed with hammers. Fast Attack Craft are small vessels capable of high speed and armed with heavy weapons, enough to allow them to "punch above their weight class" and do real damage to larger ships. As their small size reduces their range and seaworthiness, and makes them basically impossible to armor, they typically operate close to land, and rely on strength in numbers and hit-and-run attacks.

Torpedo Boats (PT)

Small boats armed with torpedoes. Mostly used just before and during World War II, they're largely obsolete now due to anti-ship missiles. Which naturally led to missile boats (see below) being designed to replace them.

During their heyday they filled a niche role somewhere between destroyers, aircraft and submarines. Like submarines, their heavy torpedoes gave them the ability to do serious damage to very large ships, even battleships—PT boats had more firepower per ton than any other vessel. Like destroyers, their small size, maneuverability, and high speed gave them the ability to defend a fleet adequately against close-range threats. Like aircraft, their relative cheapness meant they could be employed en masse.

However, they also shared the disadvantages of the types and some unique to themselves: their onboard supplies were even more limited than a submarine's or a destroyer's, limiting their range and staying power in a battle. They couldn't move as fast as aircraft and made easier targets for other ships and planes. The emphasis on speed and firepower left little room for armor.

Eventually, their role became a compromise: they were used as the commandos and raiders of the naval world. Hit and run attacks, night attacks under smokescreen, infiltration and exfiltration of special forces, evacuation of VIPs from hostile areas, and scouting were all missions under their purview.

Two particular incidents made them famous:

  • A flotilla of 6 PT boats was used to evacuate General Douglas MacArthur and his family and staff from the Philippines during the opening days of WWII, successfully evading most of the Imperial Japanese Navy over 600 nautical miles of ocean and safely delivering the general to Australia. This act of daring earned every member of the squadron a silver star and its CO, Lieutenant Commander (later Vice Admiral) John D. Bulkeley the Medal of Honor. Regardless of what you think of MacArthur, this was an impressive feat of tactics and seamanship that also served as a morale booster and an endless source of Allied propaganda during the war.
  • PT-109 became famous during and after World War II, despite being cut in half in a collision with the Japanese Fubuki-class destroyer Amagiri, mainly due to the fact that her commander at the time was John F. Kennedy. The story of his survival and how he saved what was left of his crew made him into a war hero and may have contributed to his election as president.

They're also well known in Italy due the extensive use made by the Italian Navy.

Torpedo boats became obsolete after the war mainly because other vehicles and weapons became more effective at their jobs. Their role has been taken up by submarines and missile boats. However, the way they were used and small, easy-to-identify-with crew makes them excellent fodder for dramatic fiction, so they tend to show up more often than other ships like destroyers and cruisers which did more important but more boring work.

One exception to their general obsolescence: Some countries, such as Iran, have begun to bring back the concept using semi-submersible boats, guided torpedoes, and swarm tactics as a counter to more expensive large ships. These would work best using surprise, waiting partially submerged for a larger ship to come by, then surfacing, firing their torpedoes, and running away.


  • American PT boats.
  • British Motor Torpedo Boats (MTB).
  • Italian MAS-boats (Motobarca Armata SVAN, standing for 'armed motorboat SVAN' (SVAN was the original manufacturer)).
  • German Schnellboots (E-boats to the Allies).

Missile Boats (PTG)

The logical successor to torpedo boats, substituting the slow, short-ranged torpedoes of WWII for the fast, long-ranged anti-ship missiles of today. They are subject to many of the same shortcomings as torpedo boats but in some cases the increased long-range striking power makes up for it. Like their predecessors, they typically pack a lot of firepower into a very small, fragile package.

During The Cold War the Soviet Union particularly liked the idea of lots of small, fast ships that could engage in hit-and-run attacks on other vessels... or hit-and-sink attacks, as the Soviets considered them expendable and realized they would have to be employed in large groups to account for the fact they'll take many losses before they reach launch range. After all, as the boss said, Quantity has a quality all it's own. They armed them with surface-to-surface anti-ship missiles, usually the P-15/SS-N-2 "Styx". The US, which believed in fewer but more powerful and survivable large ships lagged behind in developing these until much later, when the dominant power of anti-ship missiles was more established.

Some other countries (particularly Israel, after an Egyptian missile boat sank a destroyer of theirs in the Six Day War of 1967) took up the idea and the USSR exported the type. India put them to good use in its 1971 war with Pakistan. The US had some, but have now retired them as not cost-effective.

The missile boats do have their drawbacks, though. Actual combat showings have suggested they are not effective in a modern environment, primarily due to their small size, short range, and large antiship missiles taking up a lot of space and displacement keeping them from mounting a meaningful defense against aircraft and helicopters (though more recent models compensate by mounting surface-to-air missiles, or at least carrying man-portable SAMs with them). Due to their small size, they are not very seaworthy, have poor accommodation facilities, and short range.


  • The Soviet/Russian Project 205 Tsunami/"Osa" class is a particularly good example. The NATO designation means "wasp" in Russian- a good name for small, annoying boats with a nasty sting.
    • The Osa II class, in Finnish Navy the Tuima ("Fury") class, was generally hated by the Navy conscripts who had to serve onboard. They bore nicknames like Tuska ("Agony") class and Moskvich (after a poor quality Soviet car). The working and living conditions onboard could at best be described as Spartan (by the deck crew) and at worst hellish (by the engine crew).
  • The Norwegians have the Skjold class, which are both the fastest warships in the world (a whopping 60+ knots, the exact speed is classified) and the first operational stealth warships. They are designated as "corvettes" by Norway despite their being only slightly larger than an "Osa", on the premise that they're too seaworthy to be called mere "boats". The armament of 8 anti-ship missiles (in concealed launchers) and a 76mm gun are quite typical of a missile boat, though. These replaced the Hauk class, which were a rather more ordinary design.
  • The US Navy had the Pegasus class. They were very fast hydrofoil missile boats with an impressively heavy armament for their size (8 Harpoon missiles, double the firepower of an "Osa", and a rapid-fire 76mm gun). At least 30 were planned, but only 6 were builtnote  and they never really did anything before being retired.
  • The Israeli standard missile boat, the Sa'ar 4.5 probably pushes the boundaries of what can be considered reasonable armament for missile boats. Each ship carries 8 Harpoon missiles, and between 16 and 32 Barak anti-aircraft missiles (or 6 Gabriel anti-ship missiles), and two gun turret positions that can each mount either a 3-inch gun, a 25mm autocannon or a Phalanx CIWS. And there used to be a version of these ships that included a helipad and hanger,note  despite both versions weighing under 500 tons. This has the effect of making ships that are classified as "missile boats" almost as well armed as your average frigate. They make up for it by having as speed of "only" 34 knots, a bit faster than most frigates but mediocre for a missile boat.


The maritime equivalent of a technical. An improvised fighting vessel, usually manufactured by attaching a machine gun, anti-aircraft cannon or recoilless rifle on a speedboat manufactured as a pleasurecraft. Usually favoured by third world countries; irregulars, especially in chaotic or underdeveloped countries; and by pirates. The name derives from Swedish speedboat manufacturer Boghammar Marin AB, who manufactured the first armed speedboats for the Iranian Navy. Often called FIAC, for "Fast Inshore Attack Craft".

An arguable "sub-class" of these are suicide vessels, favored overwhelmingly by terrorists. Naturally, most of the time this is little more than a civilian speedboat packed with explosives, but back during WW2 Japan designed several purpose-built vessels as part of their eclectic array of kamikaze vehicles and weapons.

    Amphibious warfare vessels 

Amphibious warfare vessels

These ships are used to support amphibious operations.

Landing Craft (LC)

Landing craft are smaller ships of limited endurance designed to take troops from a ship and put them on the shore. They are generally deployed from transports or Amphibious Assault Ships (see below) and are not capable of independent operations. Most are simply boats with a shallow draft and a ramp in front for troops and (depending on the size) larger vehicles like trucks or tanks.

Weapons are limited mostly to machine guns for self-defense, though World War II-era variants had heavier weapons like rockets, mortars, and light artillery for supporting operations.


  • The famous Higgins Boat was a wooden landing craft manufactured by the thousands for the US and its allies during WWII and afterwards. A vivid depiction of their use in combat can be found in Saving Private Ryan and numerous other works that depict that era.
  • The US LCU (Landing Craft, Utility)
  • The US LCAC (Landing Craft, Air Cushion) is a unique take on the concept, which forms a faster but lower-capacity complement to the LCU. It is a hovercraft which is capable of actually flying a few feet above the waves and can actually drive up on shore to provide vehicles with a more stable foundation for unloading. Their great advantage lies in the fact that they're essentially small aircraft: it's nearly impossible to run one aground, short of intentionally driving into large rocks, cliffs, trees, or structures. This means they can put amphibious forces ashore in places previously thought impossible to reach, summed up in the US amphibious community adage "No beach out of reach!" LCACs are also much faster than the average landing craft, with the trade-off of larger size (can't fit as many in an Amphib) and reduced carrying capacity relative to their size.
  • Various amphibious armored vehicles can be used as landing craft if needed and conveniently double as ground transportation for troops once ashore. They have the advantage of being somewhat better armed and armored than most landing craft but the drawback of being very slow while "swimming" and requiring a particularly calm beach with a gentle slope to safely land on. Examples include the US AAV-7 and LAV-25, and the Russian BRDM and BTR series vehicles.

Amphibious Assault Ships (LS, LSD, LST, LH, LHD, LHA, LP, LPD) note 

Amphibs, or "gators" as they are referred to in the US Navy, are a sort of cross between aircraft carriers and troop transports. They are designed to take large groups of ground troops and their equipment and transport them long distances, then deploy them to shore using landing craft or helicopters. Most Amphibs have a stern gatenote  and "well deck" in the aft portion which they can flood, allowing landing craft to float in and out of the ship quickly. They also usually have a flight deck large enough to accommodate transport helos. Some, like US LHAs and LHDs, have flight decks and hangar bays which are large enough that they can transport their own helicopters and offensive aircraft, and are sometimes referred to as "assault carriers" for this reason. Like carriers, they usually have little defensive armament of their own and need to be protected. In navies without aircraft carriers, this is frequently the largest ship class around. In standard US practice, these ships do not operate alone, but instead are the lead ship of the landing force component of a larger fleet, often operating together (e.g.: an LHD, and LPD, and an LSD all together with the ground troops and aircraft distributed between them.)


  • The US LHA and LHD class ships, for the larger variety. (designation: Landing ship, Helicopter, Assault and Landing ship, Helicopter, Dock). Originally the designation LHA meant that the ship used only helicopters to deploy troops to shore, and LHD denoted that the ship also had a well deck for launching and recovering landing craft. However, then the US Marine Corps complained loudly enough that the navy decided to put well decks in their LHAs anyway, so there is really no operational difference between the two. Both have a secondary role as VTOL aircraft carriers, though their standard aircraft load is much smaller (20-30 vs. 70-80) and is optimized for close air support of ground troops. During the Cold War, it was envisioned that they could be employed as an equivalent to World War II escort carriers (CVE) in the event of a major naval war.
  • The US LPD and LSD classes, for the smaller variety. (designation: Landing ship, Platform, Dock and Landing Ship, Dock) The main difference between the two is that an LPD usually has a hangar bay for sheltering and maintaining helicopters, thereby making it a useful helicopter landing Platform.
  • The US LST class ships, now retired in US service but still used by other navies, are basically giant, oceangoing landing craft; they can actually cross the high seas and then deposit large numbers of troops, tanks, artillery, and other vehicles directly onto shore. (designation: Landing Ship, Tank) Naval jokes hold that "LST" actually stands for "large slow target". Though this originated among LST crewmen during World War II, in fact LSTs had higher survival rates than most other ship types.
  • The Spanish Juan Carlos I, a kind of mix between an STOVL carrier and an assault ship, though with emphasis on the aircraft carrier role first. Features a ski jump for launching STOVL aircraft.
    • A pair of additional ships of this design are under construction for Australia, as the Canberra class, and a third for Turkey.
  • The Italian Cavour. Like the Juan Carlos I, it's operated as a light aircraft carrier first and an amphibious ship (in this case, an LPH (Landing Platform Helicopter) second. It has a ski jump with an unusually shallow angle, which cut construction costs but also reduced the advantage of the ski jump.
  • The French Mistral class LHDs, which are broadly similar to the American ones. However their flight deck and hanger are used exclusively for helicopters, as France does not use VTOL aircraft. Three were built for the French Navy and a further two of a modified design for Russia. The latter sale was cancelled after the ships were already complete in protest over the Russian invasion of Ukraine, and the ships ended up being sold to Egypt (who also went on to purchase the navalized helicopters that Russia had planned to use on the ships).
  • The South Korean Dokdo class (similar to an LHD), one of the smallest amphibious assault ships.
  • The Soviet Ivan Rogov class is a hybrid LPD/LST, and at 14,000 tons they're the largest ships capable of beaching themselves to offload vehicles.
  • Like destroyers, the Japanese (Army in this case) pioneered the ship type with Shinshu Maru, way back in 1934. While initially simply an LSD similar to those of the US Navy, it was planned (but never carried out) to have aircraft carried within the superstructure and launched by a pair of catapults. There was no provision for the launched aircraft to land on the ship, meaning that unless floatplanes were used they would rely on the landing force to capture local airfields.
    • Another Imperial Japanese Army ship, the Akitsu Maru commissioned in 1942, was the first LHA, having a full-length flight deck in addition to a well deck for landing craft. While no arrestor wires were included, preventing typical carrier aircraft from landing, Akitsu Maru carried VTOL autogyros, making it the world's first helicopter carrier. In practice it was used primarily as an aircraft ferry, since by the time it was completed Japan had been forced onto the defensive and was no longer conducting amphibious invasions. The autogyros were used for anti-submarine purposes, carrying depth charges.

    Mine warfare vessels 

Mine warfare vessels

As their names imply, mine warfare vessels are designed around naval mines.


Exactly What It Says on the Tin. A ship whose main function is to lay naval mines to sea. Especially popular by navies whose coast is shallow, have a large archipelago or long coastline. Naval mines can be a real menace in close straits, harbours and shallow seas, and a single mine can sink a large ship. A minelayer is usually a good seagoing vessel with flush deck, with mine rails, shafts and/or scuttles attached. A passenger ferry or a ro-ro merchantman can easily converted in a minelayer by just bolting the mine rails on the car deck and embarking the mines inside, and then lowering the stern gate where the mines are to be laid. Some minelayers were well-armed enough to function as escort vessels or anti-submarine vessels. During both World Wars, submarines were also used as minelayers for their ability to lay mines without detection, and some navies had dedicated classes of minelaying submarines.


  • Finnish Navy Hämeenmaa-class minelayers.

Minesweepers (MCM)

Also Exactly What It Says on the Tin. Although, as the old navy joke goes, "Any ship can be a minesweeper...once", these are ships expressly designed for locating and neutralizing naval mines and explosives. They are usually small, slow, and virtually defenseless. However, they are designed with nifty things like non-magnetic (wooden or fiberglass) hulls, maneuvering thrusters or pods which allow them to travel in any direction and turn on a dime, and diving facilities, which allow them to successfully get near and disarm mines without detonating them. Many modern minesweepers now have Unmanned Underwater Vehicles (UUV's) to aid in locating and neutralizing mines from a safe distance. "MCM" stands for Mine CounterMeasures ship.


  • US Avenger MCMs.
  • German Seehund MCMs.


Minehunters are designed to hunt down and eliminate mines, whereas minesweepers are more tasked with disabling or detecting mines in a certain area. Basically, if you have plenty of time and want to guarantee an area of water is mine-free, use a minehunter. If you are pressed for time and need a "good enough" area that probably doesn't have any mines left, use a minesweeper. These roles may also be combined; the resulting ship is known as a Mine Countermeasure Vessel, or MCMV. These kinds of ships pioneered the use of unmanned underwater vehicles in order to allow them to investigate suspected mines without risking the ship or the lives of Explosive Ordnance Disposal divers.


Submarines are boats that can travel underwater, and fight there. Or, as the navy joke goes, they're boats for which the number of sinkings equals the number of surfacings. (Also, they are always "boats", never "ships", regardless of size. At least in US and British parlance.)

Submarines are designed, basically, to be silent hunters: sneaking up on a target, surprising them with torpedoes, and then disappearing before they can be retaliated against. This was harder in the old days; early submarines were essentially submersibles, spending most of their time on the surface and diving only when attacking or attempting to escape, since their submerged speed was very limited and so was their air supply. Not only this, but reliable sonar didn't come about until mid-WWII, and was not really good enough to search for targets (or threats) while submerged, so a submarine would have to roam around searching on the surface and then crash-dive when it found something, hoping that the boat being lower to the water would keep them from being seen until they submerged. Modern nuclear-powered submarines or those fitted with Air-Independent Propulsion (AIP), combined with massive advances in sonar technology and techniques in the 2nd half of the 20th century, brought submarines closer to the ideal of a ship which never needs to risk being on the surface and detected.

During their heyday in the first half of the 20th century, submarines were a constant source of Paranoia Fuel, due to their ability to attack without warning (on more than one occasion, capital ships were sunk in their home harbors by daring submarine commanders). During the Spanish Civil War, submarine warfare by unknown partiesnote  resulted in the Nyon Conference, where strict rules were established concerning submarines operating unescorted in the Mediterranean, with portions of the sea patrolled by British, French, Germans, and Italians to prevent submarine attacksnote  Regardless of whether it ever gets a chance to actually sink anything, submarines represent a deadly enough threat that the possibility of an enemy submarine being in your area of operations can easily tie up a couple of ships and aircraft looking for it and escorting vulnerable assets (The Falklands War for example). The risk of torpedo attack is too big a threat to be ignored.

Modern submarines can also carry anti-ship and land-attack missiles, making them even more dangerous. The deck guns of World War II are no longer present, as they increase underwater noise and are less powerful than modern torpedoes anyway. Any anti-air capacity is basically a hand-held SAM launcher carried in a waterproof box.note  Delivery of special operations forces has also become a major mission for subs since the end of the Cold War.

Submarines are sometimes found operating on their own, but any US carrier group brings a couple along for protection.

There are several different ways a submarine may be propelled:

Mechanical: Early submarines were powered either by human muscle, or using steam engines. The steam engines could only be used on the surface, however, since combustion would use up all oxygen underwater. They were quickly replaced by:

Electric: The advent of electric batteries made submarines more practical. Electric-powered submarines were developed throughout the latter half of the 19th century. Batteries were convenient and did not use oxygenn, but limited the submarine's range and endurance since they couldn't be charged in the field. Soon, however, another solution would appear in the form of:

Hybrid-Electric: The end of the 19th century was a pivotal point in submarine development. New submarines now had either a gasoline or (more commonly) a diesel engine in addition to their electric engine. Early submarines used the diesel engine to run on the surface, and the electric engine when underwater. Nowadays, the diesel engine is used to either drive the submarine's propeller, or charge electrical systems and batteries. In some respects, diesel-electric subs are more useful than nuclear-powered subs. Since they're smaller, they can operate better in shallow waters, and are harder to detect. They are also quieter, since they don't have a reactor and its cooling system running. Under the right conditions, they can be even more dangerous than a theoretically more powerful nuclear submarine, because of the lack of noise. However, they are slower, have shorter ranges and are generally not capable of spending weeks below periscope depth.

The US, UK and France have stopped using these in a combat role. Russia and China retain a fair number, finding them useful for their more limited needs (neither navy often ventures far from their shores), while smaller submarine-using navies (not all that many can afford sub fleets) have no choice but to use these.

Air-Independent Propulsion (AIP): Air-independent propulsion can either replace or supplement diesel-electric propulsion systems. This system allows submarines to operate without access to atmospheric oxygen. It can't fully replace atmospheric operating systems, but it can allow submarines to stay submerged for much longer, on the order of weeks instead of hours. They were first experimented with in World War II and the early Cold War, but failed to gain much leverage until later on, since the early AIP systems used hydrogen peroxide (which is highly explosive). Modern examples, like the German/Italian Type 212 and Spanish S-80 Plus use hydrogen fuel cells.

Today, AIP submarines are used by a few navies, with many more planning to build AIP submarines or retrofit older ones with AIP systems.

Nuclear: Powered by nuclear reactors, nuclear submarines are faster than diesel-electric submarines (and even most surface ships!). They have several further advantages: First, they can stay at sea for longer at a time. The average time between refueling a typical submarine nuclear reactor is measured in years. As a result, nuclear-powered submarines can stay at sea for months on end, until the foodstuffs on board run out, something vital needs repair, or if on a combat patrol, they run out of ammunition. Second, unlike diesel-electric boats, they do not need to periodically surface to charge the battery by running the diesels, a practice known as snorkeling-the sub literally sticks a snorkel out of the water to suck in air for the engines. Instead they make their own oxygen from seawater and scrub the carbon dioxide from the air with filters. This makes them much harder to detect by ships and aircraft.

However, like all nuclear-powered vessels, they are ruinously expensive to build and maintain, and only the US, Russia/USSR, Britain, France, China and India operate these boats. Brazil is developing some with French help.

Submarines fill several different roles:

Attack submarines (SS, SSK, SSN note )

Attack submarines are tasked specifically with locating and sinking enemy ships and other submarines. In wartime, the role of an attack sub is multifold- to defend friendly ships from attacks by enemy submarines, find and sink enemy "Boomers" (if the enemy has any), and sink enemy warships and transport ships. Due to their inherently stealthy nature, they are also frequently used for intelligence gathering and covert operations. During the Cold War (and presumably still today), attack subs from both sides would attempt to trail the opposition's missile submarines, ready to sink them if the need arose.

Along with their torpedoes, some may also carry vertically-launched missiles, for attacking land targets.

Interestingly, Israel's Dolphin class submarines, despite being diesel-electric, are theoretically capable of carrying nuclear-armed missiles and thus giving Israel a regional second-strike capability. Given Israel's fear that Iran will get nuclear weapons in the near future, it's fairly likely that the IDF is preparing for that possibility (if it hasn't already thought of that and carried it out...).

A Pakistani diesel submarine, PNS Hangor, made the first submarine kill of a surface ship since WWII in its country's unpleasantness with India in 1971. It is also one of only two successful attacks by submarines since 1945. You've probably heard of the other one.


  • The US Navy's fast-attack fleet is mainly composed of the Los Angeles Class, though some have been retired in favour of the newer Virginia class. The later ones of the former and all the latter have 12 vertical launch tubes for Tomahawk cruise missiles, but can carry them internally too.
  • There are also three Seawolf class subs in the US inventory; these are said to be the fastest and most powerful attack submarines ever built. It was originally intended to build several dozen of these, but with the end of the Cold War it turned out they were "too powerful": there was no longer a massive Soviet sub threat, and the Virginia class is only marginally less capable (the most obvious difference is that the Virgina class have half as many torpedoes...which merely means reverting to the number carried by the Los Angeles class) and much less expensive (though in reality the Virginias turned out to be only slightly cheaper due to inflation).
  • The Royal Navy's Trafalgar Class is said to have the most advanced sonar in the world. The older Swiftsure-class will soon be replaced by the Astute-class.
  • The main Soviet/Russian fast-attack sub is the "Akula" class nuclear submarine. Well, NATO call it the Akula (Shark). The Soviet Navy gave that name to the missile submarines that NATO called the "Typhoon" class, calling this the Shchuka-B, as it was an improvement of the Shchuka, NATO name "Victor III" (even though the "Akula" class is a new hull design rather than just an incremental improvement of the "Victor III"). Confusing.
  • The Soviet Union used to have the "Alfa" class (called the Lyra by the Russians, after the constellation). It was incredibly advanced for its time, featuring a welded Titanium hull, allowing to enormous dive depths, a lead-bismuth cooled reactor of immense power, and the degree of automation unprecedented to this day — for all its novel features it was crewed by just thirty men. On the other hand it lacked in stealth (though it's difficult to be stealthy running 44 knots underwater, on cruise speeds it was no worse than the other Soviet subs of the time) and it was so expensive that only a small series was built.note  Frequently featured as a "bad" submarine in Tom Clancy works.
  • Modern Russian Project 885 Yasen class is an answer to the US' Seawolf, and is similarly ruinously expensive — in fact, even more expensive than their boomer counterparts, which are much larger — and many analysts expect a Virginia-like "economy" class to surface after an initial series will be built, as the Akula class boats are getting old.
  • The Russian Kilo class diesel-electric. Relatively small and very quiet, they find a notable export success, especially in Asia, and are now bought by such disparate countries as India, China, and Vietnam.
    • Their successor, Lada class, intended to compete with the new German designs, is, however, beset by a teething problems and isn't expected to enter service (except for a single experimental boat) for a few more years.
  • The Australian Collins class diesel electric, after a lot of teething problems and controversy, is now considered to be the best of these today. Interestingly, they have an unusual "X" configuration for its tail planes (instead of the typical "+" configuration of two rudders and two dive planes, all four planes serve as both rudders and dive planes), which improves maneuverability and also makes it possible to "land" the submarine on the ocean floor without risking damage to the planes.
  • Germany still produces quite a few good diesel-electric U-boats for a number of nations. The aforementioned Israeli Dolphin class were actually built in Germany, based on Howaldtswerke-Deutsche Werke's (HDW) 209 class subs. The German Type-212 class submarines and its derivatives feature AIP.
  • The Swedish Gotland class diesel electric submarines also feature AIP, and are the first submarines to use a Stirling engine system, which allows them to stay underwater for much longer.
  • The Chinese Type-039A class diesel electric submarines.

Guided Missile Submarines (SSG, SSGNnote )

These submarines pack large numbers of cruise missiles as their primary weapon.

During World War II, German U-Boats would attack allied convoys on the surface, in large formations known as "Wolf Packs", firing torpedoes and their deck guns to sink the vulnerable freighters. With the advent of guided missiles, a single SSGN-type submarine could now do this on its own, hiding below the water and launching volleys of cruise missiles at merchant vessels in convoy. Alternatively, they could lay off the enemy coast undetected and fire missiles at enemy airbases, railway bridges and other strategic structures.


  • During the Cold War, this was a specialty of the Soviet Navy, who operated the "Echo", "Charlie", "Oscar I" and "Oscar II" classes, which would use some of them attempt to prevent the U.S. resupplying its armies in Europe during wartime or to attack carrier battle groups threatening the Soviet homeland. There were also diesel-powered versions, like the amusingly Western-named "Whiskey Long Bin" and the "Juliet".
  • Since then, the US Navy has converted some of its fleet of Ohio Class ballistic missile submarines to SSGN configuration (using the early boats of the class which were incompatible with the newer Trident II missile), designed for conventional attacks on land or sea targets using numerous Tomahawk cruise missiles. This unfortunately does lead to the odd situation of having two classes of Ohio submarines in existence at the same time; the SSGNs and the rest of the SSBNs from the class they were converted from.

Ballistic Missile Submarines (SSB, SSBN)note 

What people tend to mean when they talk about "nuclear submarines", although some of the early Soviet ones were diesel powered. These large submarines, known as "Boomers" (or "Bombers" in the Royal Navy) for obvious reasons, carry a complement of nuclear-tipped ballistic missiles, each missile usually carrying Multiple Independent Reentry Vehicles (MIRV), giving them the frightening ability to nuke several dozen targets in one go. They also carry torpedoes; these are usually - but not invariably - conventional-tipped, and mostly for self-defense.

The purpose of the SSBN is simple - to hide until such time as it is ordered to launch its missiles. It is, after all, rather easier to hide a submarine at sea which can keep moving than a large, static installation on land. Silence is golden. As with many nuclear weapons systems, SSBNs are notable in that they are typically built in order to never be used. Instead, under the logic of Mutually Assured Destruction, they are there to guarantee that if an opponent launches a nuclear First Strike against your country, you will always have enough weapons left over to launch a devastating counterstrike. Since it would be nearly impossible for the enemy to find and sink all of your subs prior to the attack, in the event your country is nuked, your ballistic missile submarines will be ready to launch retaliation later. For example, the British have a procedure where a Prime Minister can order a launch from beyond the grave by use of pre-written letters in a safe on the vessel. This guarantee of retaliation acts as a fairly strong incentive for an opponent to not launch a first strike to begin with.

Five nations operate Boomers - the US, Russia, Britain, France and China again - and the US and Russian/Soviet fleet have provided fertile ground for fiction, thanks to the dramatic potential inherent in a small, enclosed environment with the capacity for initiating worldwide destruction.


  • The Red October was a fictional (enlarged) member of the Soviet Akula/"Typhoon" class. Six of these very distinctive looking and very large submarines (the biggest ever built) were built, with one remaining in Russian service as a test platform.
  • USS Alabama, featured in Crimson Tide, is a real member of the US Ohio Class.
  • The mainstay of the Soviet/Russian boomer fleet are the boats of the project 667BDR/BDRM, AKA Kalmar/Defin class, called Delta III/IV by NATO. Deltas III, the oldest of them, are in the process of replacement by...
  • The project 955 Borey boats, designed to carry the problem-saddled Bulava SLBM, although by this time everything seems mostly settled. These are easily distinguished by the unusual reverse slope of their conning towers' face, and the virtual lack of the characteristic "hump" of the older Soviet boomers, because the solid-fueled Bulava is much more compact than their hydrazine fueled missiles.

Fleet submarine

Fleet submarine is a pre-Cold War term describing submarines with the speed and range to operate with large fleets. They saw their primary use in World War II. After the war, as submarines increased in speed and range, the term fell out of use, though it is still used by the Royal Navy to describe their attack submarines.


  • The US Gato and Balao-class.
  • The Japanese Kaidai-type.

Submarine aircraft carrier

Submarines capable of carrying aircraft. The concept was tested during and after World War I, but the only country to make any serious use of them was Japan.


  • French submarine Surcouf also had a hangar for carrying an observation plane.
  • The Japanese I-400 class submarine was the largest submarine in World War II, capable of carrying three Aichi M6A1 Seiran seaplanes. Three were completed.

Cruiser submarine

Cruiser submarines are large submarines designed to operate away from bases and support systems for long periods of time. They were tested after World War I, but didn't see much use, as their large size makes them slow to dive, as well as making them large and easy-to-find targets.


  • The French submarine Surcouf, which, at the time of her construction, was the largest submarine built. She also mounted a 203mm gun, the largest artillery ever mounted by a submarine.
  • The British HMS X1, which carried four 5.2 inch guns in two turrets, and was also the largest submarine ever built at the time of her construction in 1915.

Coastal submarine

As their names imply, coastal submarines are small, maneuverable submarines designed to operate near the shore. They have limited resources, but can go to places larger submarines can't, and are much harder to detect. They are well-suited for defensive duties, as well as laying mines.

Midget submarine

Midget submarines are very small submarines with limited range, small crew complements, and little or no living accommodations. They typically operate from motherships. They are mainly used for special forces operations, like harbor penetration or delivering commandos.


  • The Kriegsmarine Biber and Seehund-class.
  • The British XE-class.

    Auxiliary ships 

Auxiliary Ships (AA)

The backbone of any naval fleet. These carry extra supplies- food, fuel, ammo etc. They can also be used for intelligence or command stuff too. They will be found with small defence capabilities, but will need protection from other ships. Many of these ships are designed to be able to refuel, rearm, and resupply other ships at sea, in order to extend the time they can spend out of port. When the practice, called "Underway Replenishment," was invented in the 1920's and 30's, it was practically a secret weapon for the US, who had much less of a dependence on foreign ports and much longer endurance than everyone else. The weapon came to life in the Pacific by 1944, with the US being able to operate its fleet anywhere it chose for as long as it felt like.

There are large numbers of sub-types. For example, the following is still not a complete list:
  • AKV- Cargo ship and aircraft ferry.
  • APB- Self-propelled barracks ship.
  • AGF- Miscellaneous research ship.
  • AE- Ammunition ship; specifically carries ammunition.
  • AFS- Combat Stores Ship; carries ammo and various other supplies.
  • AKE- Dry Cargo/Ammunition ship; designed to do the job of both AEs and AFSs
  • AC- Collier; carries coal to refuel other ships. Replaced by Oilers as ships transitioned from coal to oil for their fuel source.
  • AO- Oiler; carries fuel and other liquids. These replaced Colliers.
  • AOE- Fast Combat Support Ship; a large ship that carries fuel, ammo, and supplies. The "E" must stand for "everything". Additionally, they're called "fast" because they are designed to keep up with dedicated warships like an aircraft carrier and its escorts.
  • AH- Hospital Ship. Exactly What It Says on the Tin.
  • AP- Transport; transports troops.
  • APA - Attack Transport; oceangoing troopships that carry their own landing craft, allowing them to land their troops without needing a dock or tenders.
  • APD- High-speed transport; a destroyer converted to transport small (usually elite) units. This was a US-only thing during WWII.
  • AD- Destroyer tender, carries supplies, repair parts, and support facilities for destroyers. Now obsolete, they were common back when destroyers were much smaller and had shorter endurance.
  • AS- Submarine tender. Likewise.
  • AGI- Intelligence gathering vessels, basically spy ships, typically disguised as fishing trawlers. Although less obvious than an outright warship for intelligence gathering, they can often be identified by the presence of way more antennae than required by your typical fishing vessel. They typically operate alone.
  • LCC- Command Ship. Originally meant for the commander of an amphibious assault (hence the LC for "landing craft"), as it was expected a naval commander would travel by carrier or battleship. The US Navy now uses these to command entire theaters.
  • AG- Miscellaneous Auxiliary. Various support ships which perform their duties out at sea. In the US Navy, this has included many older battleships decommissioned due to obsolescence or treaty/financial reasons which were converted into training ships (often replacing the main batteries with Anti-Air guns) or testing ships (in this role, the USS Mississippi would be the first US battleship, and the only WWI era dreadnought, to launch guided missiles).
    • Torpedo boat tenders in the US Navy used this designation as well. As with the previous tenders, they provided supplies, repair facilities, and other support facilities (including a nicer place to sleep) for torpedo boats.
  • IX- Unclassified Miscellaneous Vessels. A designation used by the US Navy for any ships in the inventory which just don't fit anywhere in the classification system, typically unique vessels or ships used for testing purposes. This has included various support ships, two freshwater aircraft carriers, and the sailing frigate USS Constitution.


  • Chiwawa class oiler (AO)- five used by US in World War II. Two remain in private service today.
  • Berlin class replenishment ship (Germany)- two built, two planned.
  • Project 160 "Altay" class- old Soviet/Russian oilers, but still around.
  • Sacramento class fast combat support ship (AOE) - four used by the US Navy until 2005, they were the first supply ships to be able to keep pace with a carrier battle group. To achieve superior speed compared to other auxiliaries, the steam turbines originally intended for the partly-built 5th and 6th Iowa class battleships were employed.
    • Their successors, the Supply class AOEs, are powered by gas turbine (jet) engines for the same reason.
  • US Henry J. Kaiser class AOs
  • US Lewis and Clark class AKEs
  • USS Jupiter (AC-3), a collier which entered service shortly before World War I. Most noteworthy for her inter-war refit to become USS Langley (CV-1), the United States Navy's first aircraft carrier.


Miscellaneous vessels

This category covers vessels that don't fall under any of the other classifications.


This term was used by the French and Portuguese navies (where, in both languages, it means "warning") to designate small warships used for colonial service. They are typically about the same size or smaller than corvettes, and comparable in role to a gunboat or light escort vessel. The term is rarely used nowadays.

Coastal defence ship

A likewise nowadays redundant class, this type of ship was very popular amongst small countries' navies. More like mobile coastal artillery batteries than true bluewater ships, these ships usually were of size of a frigate but carried the armament of a heavy cruiser, providing more firepower than any other ship in shallow waters. Some were purpose-built vessels, while a few obsolete battleships were reclassified and reassigned for coastal defence duty. Often called "armoured ships" (panserskepp, panssarilaiva etc). Nevertheless, they carried heavy punch and some of them stayed in service until 1960s.

Merchant raider/auxiliary cruiser

Merchant raiders, or auxiliary cruisers, were armed warships disguised to look like ordinary merchant ships. The main difference between a merchant raider and a simple armed merchant vessel is that the latter's weapons are primarily defensive, while merchant raiders actively hunt for and sink other vessels.

These vessels were heavily used by all sides in both World Wars.


Taking their name from the first of the American ironclads, monitors are small ships carrying very powerful armament. They typically have a low-freeboard hull, designed for use in shallow water.

Named for the USS Monitor, the first of their kind to be built and see combat in the American Civil War, they were originally designed as coast-defense ships, for use in defence of naval bases and other strategic seaside positions in the event that something happened to the main fleet (or it had to be elsewhere). By the First World War, the term came to signify a coast-offence ship, tasked with shore bombardment and frequently armed with a single main-gun turret taken from an obsolete battleship or heavy cruiser. Although not specifically intended for ship-to-ship duels, two of them were responsible for the destruction of a German cruiser which was sheltering in shallow waters during the First World War, as they were the only ones which could make their way far enough up-river with a heavy enough armament. A few monitors continued to see service through the Second World War, operating as gunfire support vessels or as river patrol boats. During The Vietnam War, vessels of this description were used by the US as part of the "brown water Navy" operating in the rivers, deltas, and swamps of South Vietnam.

This class of ship is now a redundant anachronism, although the concept still vaguely exists in the form of (abandoned) plans for an "arsenal ship", a platform specifically designed to carry one or two surface-bombardment guns and a VERY large number of (non-nuclear) cruise missiles for use against pinpoint land targets. A handful of monitor-type vessels remain in service today, including the Brazilian monitor Parnaíba, the oldest commissioned warship still in active service, sailing the seas just shy of eighty years.


Q-ships were merchant vessels armed with hidden weapons, designed to lure out and attack enemy submarines. They saw service in both World Wars, but were not particularly successful in either war.

Rigid (Hull) Inflatable Boats (RIB, RHIB)

Basically, small speedboats with a light rigid hull for structure and inflatable pontoons for buoyancy and to make them more forgiving when docking or coming alongside a ship. Often mounted with a light to medium machine gun. Sort of parasite boats, many naval vessels carry a number of these for boarding operations, inport security, search and rescue, and other general purpose jobs. RIBs are the latest iteration of this kind of vessel; in the past, using different designs they have been known as Gigs, Barges, Cutters, Yachts, Runabouts, Whaleboats, and simply Boats.

Training ship

A ship meant for training new sailors, either in sailing techniques, or as floating classrooms. They may be sail vessels, or old hulks or decommissioned warships.