Challenger-class cruiser

The Challenger-class cruisers were a pair of second-class protected cruisers built for the Royal Navy in the first decade of the 20th century. One ship, HMS Encounter (1902), was later transferred to the Royal Australian Navy.

Design and description
The Challenger-class cruisers were essentially repeats of the previous Highflyer class, albeit with more powerful propulsion machinery. They were designed to displace 5880 LT. The ships had a length between perpendiculars of 355 ft, a beam of 56 ft and a draught of 21 ft. Their crew consisted of 490 officers and other ranks.

The ships were powered by two 4-cylinder triple-expansion steam engines, each driving one shaft, using steam provided by 18 Babcock & Wilcox (HMS Challenger (1902)) or Dürr (Encounter) water-tube boilers. These boilers were heavier and bulkier, but more powerful than the Belleville boilers used in the Highflyer class. Sir William White, Director of Naval Construction, was uncertain if the extra power would offset the weight sufficiently to reach 21 kn and rated the ships at 20.75 kn. The boilers were designed to produce enough steam to allow the engines to reach 12500 ihp. The ships easily exceeded their designed power and speeds during their sea trials. They carried a maximum of 1150 LT of coal.

The main armament of the Challenger class consisted of 11 quick-firing (QF) 6 in Mk I guns. One gun was mounted on the forecastle and two others were positioned on the quarterdeck. The remaining eight guns were placed port and starboard amidships. They had a maximum range of approximately 10000 yd with their 100 lb shells. Eight QF 12-pounder 12 cwt guns were fitted for defence against torpedo boats. One additional 12-pounder 8 cwt gun could be dismounted for service ashore. They also carried six 3-pounder Hotchkiss guns and two submerged 18-inch (450 mm) torpedo tubes.

The ships' protective deck armour ranged in thickness from 1.5 to 3 in. The engine hatches were protected by 5 in of armour. The main guns were fitted with 3-inch gun shields and the conning tower had armour 6 inches thick.

Ships

 * HMS Challenger (1902) - Sold 1920
 * HMS Encounter (1902) - To Australia in 1912 as HMAS Encounter, renamed Penguin 1923, scuttled 1932.