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.
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[edit] Design features
After the introduction of the explosive shell, warships needed additional protection, and protected cruisers were constructed from about 1880.
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, and were armed with up to a dozen single guns of between 3.9 and 6 inches (100 to 152 mm) in calibre. They were capable of speeds of 18 - 23 knots.
Around 1910, armour plate began to increase in quality and steam turbine engines, lighter and more powerful than previous reciprocating engines. came into use. Existing protected cruisers became obsolescent as they were slower and less well protected than new ships. Oil firing of boilers was introduced, making side bunkers of coal unnecessary and losing the protection they afforded. Protected cruisers were replaced by "light armoured cruisers" with a side armoured belt and armoured decks instead of the single deck, later developed 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 between the late 1880's and 1905, and built large numbers of them for their extensive trade protection requirements. For the majority of this period, these cruisers were built with a "protected," rather than armoured scheme of protection for their hull. First class protected cruisers were as large and as well-armed as armoured cruisers, and were built as an alternative to the large first class armoured cruiser from the late 1880's till 1898. Second class protected cruisers were smaller, displacing 3,000-5,500 tons and were of value both in trade protection duties and scouting with the fleet. Third class cruisers were smaller, lacked a watertight double bottom, and were intended primarily for trade protection duties, though a few small cruisers were built for fleet scout roles or as "torpedo" cruisers during the "protected" era.
The introduction of Krupp armour in six inch thickness rendered the "armoured" protection scheme more effective for the largest first class cruisers, and no large first class protected cruisers were built after 1898. The smaller cruisers, unable to bear the weight of heavy armoured belts retained the "protected" scheme up to 1905, when the last units of the Challenger and Highflyer class were completed. There was a general hiatus in British cruiser production after this time, apart from a few classes of small, fast scout cruisers for fleet duties. When the Royal Navy began building larger cruisers(+4000 tons) again around 1910, they used a mix of armoured decks and/or armoured belts for protection, depending on class. These modern, turbine powered cruisers are properly classified as light cruisers.
[edit] Surviving examples
A few protected cruisers have survived as museum ships:
- Aurora - St Petersburg
- HNLMS Bonaire - Delfzijl, Netherlands
- USS Olympia - Philadelphia
- Bow section and bridge of Puglia - La Spezia
