Heavy cruiser
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The term heavy cruiser is used to refer to large cruisers, a form of warship. Heavy cruisers are smaller than battleships and battlecruisers of the same era.
The first examples of large cruisers were the British Hawkins class of 12,000 tons which were built during World War I most of them entering service after the war. The preceding Town class weighed in at some 5,000 tons.
The term was given a definition by the Washington Naval Treaty of 1921. The treaty, which sought to limit an arms race in warships, restricted the construction by nations of all large warships. Among its terms, cruisers could be no more than 10,000 tons standard displacement with armament no greater than 8-inch (203 mm) guns. As a result of the treaties limits on the largest warships - the battleships - the major naval powers started to build large cruisers, to build up their naval strength. These tended to be at the top end of the allowable weight and were typically armed with eight or ten 8 inch guns. In 1930 the Washington Naval Treaty was extended by the London Naval Treaty which split the treaty definition of a cruiser into Heavy Cruiser with guns larger than 6.1 inch (155 mm) and "light cruiser" with smaller caliber guns. The upper limit of 10,000 tons displacement still applied to both.
In the 1930s several navies began to secretly flout the tonnage limits. The Japanese who were planning on withdrawing from the treaty built the Mogami class with a displacement of over 12,000 tons. She was designed so that her five 6.1-inch gun triple turrets could be replaced with twin 8-inch gun turrets and the ships of the class were rearmed in that way shortly before World War II.
By the mid 1930s, Britain, France and Italy had ceased building heavy cruisers. A weakness of heavy cruisers was that they were usually too weak in armour. Within the tonnage limits, mounting the heavier guns left them with insufficient protection against a ship with the same size weapons. Armament based on 8-inch (203 mm) guns was considered overall to be inferior to that using 6-inch (152 mm) guns. The latter fired faster and more of them could be carried for the same weight as for the 8 inch. The heavier shell of the 8 inch was little advantage because ships that could withstand a 6 inch (152 mm) hit were well-protected against 8 inch shells. This led to the construction "light cruisers" of 10,000 ton with twelve to fifteen 6 inch guns that were otherwise identical to heavy cruisers.
Big gunned cruisers were still being built. The Germans built their Hipper class heavy cruisers of 14,000 tons - Germany was not covered by the Washington treaty - the Treaty of Versailles was supposed to limit their shipbuilding. The American Baltimore class, also over 14,000 tons was built during World War II after the end of the treaty. Late in the war, the United States developed a "semiautomatic" loading system for their 8-inch guns that greatly improved the firing rate.
The last heavy cruisers were built during the war. The biggest were the Alaska class of "large cruiser", which were often referred to as battlecruisers because their size and armament approximated that of a small battleship. The Baltimore class consisted of seventeen ships, including six of the derived Oregon City and Des Moines classes, were completed. Additionally, two aircraft carriers were built on a Baltimore-derived hull, the Saipan class (CVL-48 class).
The heavy cruisers fell out of use after World War II. Some existing US heavy cruisers lasted until the 1970s, sometimes after conversion to guided missile cruisers (US hull symbol CG).
In the United States Navy, the term first came into official use in 1930, with the hull classification symbol CA which it took over from the Armored cruiser. With the development of guided missile cruisers in the 1950s, the designation system changed to designate cruisers by their primary armament. Primarily gun-armed cruisers were designated "gun cruisers" (hull classification symbol CA) while primarily missile-armed cruisers were designated "guided missile cruisers" (hull classification symbol CG).
Many other nations built or possessed heavy cruisers in the period 1920-1945, namely Britain, Japan, France, Italy, Germany, USSR, Spain, and Australia. They played a similar role to that of the armored cruisers 40 years earlier.
The only heavy cruisers in existence as of 2006 are the USS Des Moines (CA-134) (on hold for possible donation), and USS Salem (a museum ship).
In popular culture
The term "heavy cruiser" has seen a revival in military-oriented science fiction. In Star Trek, the USS Enterprise and Enterprise-A were ostensibly of the "Constitution class" of heavy cruisers. In Babylon 5, Earthforce fields the "Hyperion-class heavy cruiser". Many other science fiction universes boast classes of heavy cruisers among their warring factions, and the term seems to be a catchall for larger, heavily-armed warships. Many of these spaceborne heavy cruisers also carry squadrons of fighters, adding a carrier role to their big guns. It is not always clear whether the science fiction writers who use the term heavy cruiser realize that this entire class of vessels was the result of a treaty rather than anything a rational navy would have invented on its own initiative. However, in practice, these space heavy cruisers have more in common with battleships than with cruisers, frequently being the most powerful ship their government has to offer.
See also
de:Schwerer Kreuzer it:Incrociatore pesante ja:重巡洋艦 pl:Krążownik ciężki sr:Тешка крстарица