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Leander-class light cruiser

The Leander class was a class of eight light cruisers built for the Royal Navy in the early 1930s that saw service in World War II. They were named after mythological figures, and all ships were commissioned between 1933 and 1936. The three ships of the second group were sold to the Royal Australian Navy (RAN) before World War II and renamed after Australian cities.

Design

Formal design work on the Leander class began in 1928 and was influenced by the York-class heavy cruiser. The ships were designed for long-range patrols, scouting, and trade protection duties. Originally, more Leander-class ships were planned. However, the general displacement limit set by the arms limiting London Conference meant the Royal Navy had just 91,000 tons of total cruiser displacement remaining. As a result, efforts to reduce displacement further led to the design of the Amphion-class light cruisers.

Propulsion

Speed was 32 knots (59.3 km/h; 36.8 mph), and 845 tons of armour was provided. During trials in December 1932 Leander made 32.45 knots (60.1 km/h; 37.3 mph) with 72,430 shaft horsepower (54,010 kW) at 7265 tons displacement and 31.4 knots (58.2 km/h; 36.1 mph) with 73,140 shp (54,540 kW) at 9010 tons deep displacement. The first five vessels did not contain dispersed machinery; the boiler rooms were arranged together and trunked into a single large funnel, a unique feature amongst British cruisers. This meant that damage amidships was more liable to disable all the boiler rooms.

Protection

Protection was light and confined mostly to vital areas of the ship, as her intended role was trade protection and engaging auxiliary cruisers this was deemed an acceptable compromise. The magazines were protected by a box structure with 76 mm (3 in) walls. The main deck and turrets were protected by 25.4 mm (1 inch) thick armour, sufficient to protect against small caliber weapons.

Armament

The 7,000-7,200 ton Leanders were armed with eight BL 6 inch Mk XXIII naval guns in superfiring twin turrets, two forward and two aft. The turrets were based on a design trialled on HMS Enterprise with an anticipated rate of fire for the guns of eight rounds per minute, with a firing range of 22,700 m.

Their secondary armament consisted of four high-angle QF 4 inch Mk V naval guns, which were later replaced by twin mountings for eight guns (the later high angle QF 4 inch Mk XVI naval gun). Their close-range anti-aircraft weaponry consisted of twelve 0.5-inch (13 mm) Vickers machine guns in three quadruple mounts.

They also mounted a bank of four 21-inch (530 mm) torpedo tubes on each beam and provision was made in the design for the carriage of two catapult-launched Fairey Seafox aircraft. Modified catapults were later fitted which allowed the launching of heavier aircraft such as the Supermarine Walrus.

Modifications

To alleviate wetness in heavy seas, the hull plating was extended aft to the rear 4" gun mount. The single 4in mounts were replaced by twin Mk XIX between 1936 and 1938, although Achilles did not receive this upgrade until a wartime refit.

Leander and Achilles received more powerful catapults that allowed them to operate the Supermarine Walrus ahead of their transfer to the Pacific.

During the war, significant modifications were made to the vessels. Various additional anti-aircraft armament was added, and the two New Zealand vessels removed a turret to carry heavier 20 mm and 40 mm anti-aircraft guns in its place. Improvements in radar technology subsequently reduced the advantages of floatplanes, and surviving ships had their aircraft handling facilities removed to reduce topweight.

Amphion Class

Three ships described at the time as Amphion-class, or Modified Leanders, were ordered for the Royal Navy. These ships differed from the original Leander-class ships in having unit machinery and two funnels. The unit machinery provided better protection against damage but required more space. The ships were fitted with more powerful boilers, reducing the number of boilers from six to four, but keeping the same power output. The new boilers were larger than those fitted to the first ships, so the armour belt was raised and extended.

The beam was increased by 20in to retain stability as a result of the armour belt surrounding the longer machinery space. The extra beam and length effectively negated the weight savings provided by the improved boilers.

Consideration was given to mounting triple turrets in "A" and "Y" positions, but these were cancelled during the design stage.

All three ships were transfered to the Royal Australian Navy in the late 1930s. Sydney and Perth were unaltered before their loss. Hobart had aircraft and catapult removed during the war and AA and radar considerably enhanced.

Ships in class

Name	Builder	Laid down	Launched	Commissioned	Fate
Leander	HM Dockyard Devonport	8 September 1930	24 September 1931	24 March 1933	Transferred to Royal New Zealand Navy as HMNZS Leander, 1941–1945; Broken up at Blyth, 1950
Orion	HM Dockyard Devonport	26 September 1931	24 November 1932	18 January 1934	Broken up at Dalmuir, 1949
Neptune	HM Dockyard Portsmouth	24 September 1931	31 January 1933	23 February 1934	Sunk in minefield off Tripoli, 19 December 1941
Ajax	Vickers Armstrong, Barrow-in-Furness	7 February 1933	1 March 1934	12 April 1935	Broken up at Newport, 1949
Achilles	Cammell Laird, Birkenhead	11 June 1931	1 September 1932	10 October 1933	Transferred to Royal New Zealand Navy as HMNZS Achilles, 1941-1946; Sold to Indian Navy as HIMS Delhi, 1948; Scrapped 1978
Perth (ex-Amphion)	HM Dockyard, Portsmouth	22 June 1933	27 July 1934	15 June 1936	Sold to Royal Australian Navy as HMAS Perth, 1939; Sunk in torpedo attack, 1 March 1942
Hobart (ex-Apollo)	HM Dockyard, Devonport	15 August 1933	9 October 1934	13 January 1936	Sold to Royal Australian Navy as HMAS Hobart, 1938; Broken up at Osaka, 1962
Sydney (ex-Phaeton)	Swan Hunter, Wallsend	8 July 1933	22 September 1934	24 September 1935	Sunk in surface action, 19 November 1941 with all hands