Protected cruiser

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Protected cruisers were a type of naval cruiser of the late 19th century. They were so known because their armour protected their vital machine spaces. They were less well protected than armoured cruisers which also had a belt of armour along the sides.

1 Design features
2 Protected cruisers in the United States Navy
3 Protected cruisers in the Royal Navy
4 Surviving examples
5 See also

[edit] Design features

In the protected cruiser, the majority of the armour was arranged on a special deck inside the vessel, protecting the boilers and steam engines. It was angled on either wing, appearing trapezoid in cross-section, which gave the best protection for the least amount of armour. The armour tended to range from 2 to 3 inches (5 to 7.5 cm) in thickness, and was thickest on the slopes where it afforded most protection. Protected cruisers would also use armour for the guns and conning tower. The coal bunkers were arranged so that they offered the most protective value.

Typically protected cruisers displaced from 2,500 to 7,000 tons. The armament of protected cruisers was up to a dozen single guns of between 3.9 and 6 inches (100 to 152 mm) in calibre. They were capable of 18 - 23 knots.

The first protected cruisers appeared about 1880, the development of the explosive shell making this inevitable. Around 1910, armour plate began to increase in quality and the steam turbine engines began to be used, which was lighter and more powerful than the traditional reciprocating engine. Existing protected cruisers were slower and less well protected than new construction and were rendered obsolescent. Additionally, oil firing of boilers was introduced, eliminating the protective side bunkers of coal and the protection they afforded. Thus, countries started to build "light armoured cruisers", which had a side armoured belt and armoured decks instead of the single deck. The light cruiser was later elaborated into heavy cruisers.

[edit] Protected cruisers in the United States Navy

The first protected cruiser of the United States Navy "New Navy" was the USS Atlanta, launched in October 1884, soon followed by the Boston in December, and Chicago a year later. A numbered series of cruisers began with Newark (Cruiser No. 1), although Charleston (Cruiser No. 2) was the first to be launched, in July 1888, and ending with another Charleston, Cruiser No. 22, launched in 1904.

The reclassification of 17 July 1920 put an end to the US usage of the term "protected cruiser", the existing ships designated as plain "cruisers" with new numbers (so that the armored cruisers could retain their numbers unchanged).

[edit] Protected cruisers in the Royal Navy

The British Royal Navy rated cruisers as first, second and third class. First class protected cruisers were as large and well armed as armoured cruisers (which were also rated as first class). Second class cruisers displaced around 4,000 tons and potentially were required to serve in the line of battle. Third class cruisers were smaller yet, lacked a watertight double bottom and were not intended for fleet duties. There were no second or third class armoured cruisers as such a ship had to be very large. The last protected cruisers were the Town class of 1910, which were rated as second class. These were essentially an intermediate type, with a side belt of armour and turbine engines, but with mixed firing, thus retaining some protective coal bunkers.