Ship class should not be confused with Ship classification.
A ship class is a group of ships of a similar design.[1] This is distinct from a ship type, which might reflect a similarity of tonnage or intended use. For example, is a nuclear aircraft carrier (ship type) of the (ship class).
In the course of building a class of ships, design changes might be implemented. In such a case, the ships of different design might not be considered of the same class; each variation would either be its own class, or a subclass of the original class (see for an example). If ships are built of a class whose production had been discontinued, a similar distinction might be made.
Ships in a class often have names linked by a common factor: e.g. s' names all begin with T ; and s are named after American battles . Ships of the same class may be referred to as sister ships.
The name of a naval ship class is most commonly the name of the lead ship, the first ship commissioned or built of its design. However, other systems can be used without confusion or conflict. A descriptive name may be used; for example it was decided to group destroyers made to the same design as HMS Tomahawk, all named after weapons, as the rather than Tomahawk class.
In European navies, a class is named after the first ship commissioned regardless of when it was ordered or laid down. In some cases this has resulted in different class names being used in European and U.S. references; for example, European sources record the s of the United States Navy as the "Maryland class", as was commissioned before .
The West German Navy (Bundesmarine) used a three-digit type number for every class in service or in advanced project state. Modified versions were identified by a single letter suffix. After the reunification of Germany the German Navy (Deutsche Marine) kept the system. Informally, classes are also traditionally named after their lead ships.
The Indonesian Navy has a traditional naming system for its ships. In addition, the ship's type and missions can be identified by the first number on the ship's three-digit hull number, which is placed on the front bows and the back of the stern. The naming convention is:[2]
See also: List of ships of Russia by project number. Russian (and Soviet) ship classes are formally named by the numbered project that designed them. That project sometimes, but not always, had a metaphorical name, and almost always had a NATO reporting name. In addition, the ships of the class would have a number prefixed by a letter indicating the role of that type of vessel. For example, Project 641 had no name, though NATO referred to its members as s.
The ship classification does not completely correspond common designation, particularly for destroyers, frigates and corvettes. Russia has its own classification system for these ships:
The British Royal Navy (RN) has used several methods of naming classes. In addition to the accepted European convention, some classes have been named after a common theme in the included ships' names, e.g., s, and some classes were implemented as an organizational tool, making traditional methods of naming inefficient. For instance, the is also known as the A class. Most destroyer classes were known by the initial letter used in naming the vessels, e.g., s. Classification by letter also helped to conflate similar smaller classes of ships as in the case of the A-class destroyers of 1913 whose names spread across the alphabet. Since the end of the Second World War, Royal Navy ship classes have also been known by their type number (e.g. Type 45 destroyer.)
See also: United States ship naming conventions. For the United States Navy, the first ship in a class to be authorized by Congress is the designated class leader and gives the name to the class, regardless of the order in which the ships of that class are laid down, launched or commissioned.[3] Due to numbering conventions, the lead ship often has the lowest hull number of its class. (During World War II, the award of construction contracts was not always congruent with completion, so several ships had higher hull numbers than later ships.)[4]
Before the 1920s, naval vessels were classified according to shared characteristics.[5]
The unofficial retro-applying of ship classes can occasionally lead to confusion. For example, while American works consistently adhere to the City- and Columbia-class monikers, works of British origin refer to the same classes as Cairo class and Tennessee class respectively, in compliance with the modern Royal Navy naming conventions.
By the time the United States entered World War II, the current naming convention was in place, though it remains unclear as to exactly how and when the practice originated.
Merchant ships are almost always classed by a classification society. These vessels are said to be in class when their hull, structures, machinery, and equipment conform to International Maritime Organization and MARPOL standards. Vessels out of class may be uninsurable and/or not permitted to sail by other agencies.
A vessel's class may include endorsements for the type of cargo such as "oil carrier", "bulk carrier", "mixed carrier" etc. It may also include class notations denoting special abilities of the vessel. Examples of this include an ice class, fire fighting capability, oil recovery capability, automated machinery space capability, or other special ability.