Editing Courageous-class battlecruiser (section)

== Design and description ==
[[File:Glorious class cruiser diagram Brasseys 1923.jpg|thumb|left|Right elevation and plan view of the ''Courageous'' class from [[Brassey's Naval Annual]] 1923]]

The first two ''Courageous''-class battlecruisers were designed in 1915 to meet a set of requirements laid down by the [[First Sea Lord]], Admiral Fisher, with his Baltic Project in mind. They were to be large enough to ensure that they could maintain their speed in heavy weather, have a powerful armament and a speed of at least {{convert|32|kn}} to allow them to outrun enemy [[light cruiser]]s. Their protection was to be light for a cruiser, with {{convert|3|in|0}} of armour between the waterline and the forecastle deck, [[anti-torpedo bulge]]s amidships and the machinery as far inboard as possible, protected by triple [[torpedo bulkhead]]s. Shallow draught was of the utmost importance and all other factors were to be subordinated to this. The [[Director of Naval Construction]] (DNC), [[Sir Eustace Tennyson-d'Eyncourt, 1st Baronet|Sir Eustace Tennyson-d'Eyncourt]], responded on 23 February 1915 with a smaller version of the {{sclass|Renown|battlecruiser|2}}s with one less gun turret and reduced armour protection. The [[Chancellor of the Exchequer]] had forbidden any further construction of ships larger than light cruisers in 1915, so Fisher designated the ships as large light cruisers to evade this prohibition. If this restriction had not been in place, the ships would have been built as improved versions of the preceding ''Renown'' class. The two ships were laid down a few months later under a veil of secrecy, so they became known in the [[Royal Navy]] as "Lord Fisher's [[wikt:hush-hush|hush-hush]] cruisers" and their odd design also earned them the nickname of the ''Outrageous'' class.<ref name=b03>Burt, p. 303.</ref>

Their half-sister ''Furious'' was designed a few months later to meet a revised requirement specifying an armament of two [[BL 18 inch Mk I naval gun|BL 18-inch Mk I]] guns, the largest guns ever fitted on a Royal Navy ship, in single turrets with the ability to use twin {{convert|15|in|0|adj=on}} gun turrets if the 18-inch guns were unsatisfactory. Gunnery experts criticized this decision because the long time between [[salvo]]es would make spotting corrections useless and reduce the rate of fire and thus the probability of a direct hit. Her secondary armament was upgraded to [[BL 5.5 inch Mark I naval gun|BL {{convert|5.5|inch|0|adj=on}} Mk I]] guns, rather than the {{convert|4|in|0|adj=on}} guns used by the first two ships, to compensate for the weakness of the two main guns against fast-moving targets like [[destroyer]]s. Her displacement and beam were increased over that of her half-sisters with slightly less draught.<ref name=b03/>

The Baltic Project was only one justification for the ships.  Admiral Fisher wrote in a letter to the DNC on 16 March 1915: "I've told the First Lord that the more that I consider the qualities of your design of the Big Light Battle Cruisers, the more that I am impressed by its exceeding excellence and simplicity—all the three vital requisites of gunpower, speed and draught so well balanced!"<ref>Roberts, p. 51.</ref> In fact they could be considered the epitome of Fisher's belief in the paramount importance of speed over everything else. Fisher's adherence to this principle is highlighted in a letter he wrote to Churchill concerning the battleships of the 1912–13 Naval Estimates. In the letter, dated April 1912, Fisher stated: "There must be sacrifice of armour ... There must be further VERY GREAT INCREASE IN SPEED ... your speed must vastly exceed [that of] your possible enemy!"<ref>Roberts, p. 46.</ref>

Fisher's desire for a shallow draught was not merely based on the need to allow for inshore operations; ships tended to operate closer to [[deep load]] than anticipated and were often found lacking in [[freeboard (nautical)|freeboard]], reserve buoyancy and safety against underwater attack. This experience led the DNC to reconsider the proportions of the hull to rectify the problems identified thus far. The ''Courageous''-class ships were the first products of that re-evaluation.<ref>Roberts, p. 53.</ref>

=== General characteristics ===
The ''Courageous''-class ships had an [[length overall|overall length]] of {{convert|786|ft|9|in|m|1}}, a [[beam (nautical)|beam]] of {{convert|81|ft|m|1}}, and a [[draft (ship)|draught]] of {{convert|25|ft|10|in|m|1}} at deep load. They displaced {{convert|19180|LT|t}} normally and {{convert|22560|LT|t|0}} at deep load. They had a [[metacentric height]] of {{convert|6|ft|1}} at deep load and a complete [[double bottom]].<ref name=r65>Roberts, pp. 64–65.</ref>

Their half-sister ''Furious'' was the same length, but had a beam of {{convert|88|ft|m|1}} and a [[draft (ship)|draught]] of {{convert|24|ft|11|in|m|1}} at deep load. She displaced {{convert|19513|LT|t|0}} at load and {{convert|22890|LT|t|0}} at deep load. She had a metacentric height of {{convert|5.33|ft|1}} at deep load.<ref name=r65/>

=== Propulsion ===
To save weight and space the ''Courageous''-class ships were the first large warships in the Royal Navy to have geared [[steam turbine]]s and [[water-tube boiler|small-tube boilers]] despite the latter's significantly heavier maintenance requirements. Furthermore, to save design time, the turbine installation used in the light cruiser {{HMS|Champion|1915|2}}, the navy's first cruiser with geared turbines, was simply doubled. The [[Parsons Marine Steam Turbine Company|Parsons]] turbines were arranged in two engine rooms and each of the turbines drove one of the four propeller shafts. ''Furious''{{'}}s propellers were {{convert|11|ft|6|in|m|1}} in diameter. The turbines were powered by eighteen [[Yarrow Shipbuilders|Yarrow]] boilers equally divided among three boiler rooms. They were designed to produce a total of {{convert|90000|shp|lk=in|0}} at a working pressure of {{convert|235|psi|kPa kg/cm2|0|abbr=on|lk=on}}, but achieved slightly more than that during ''Glorious''{{'}}s trials, although she did not reach her designed speed of {{convert|32|knots}}.<ref>Roberts, pp. 71, 74, 76, 79.</ref>

They were designed to normally carry {{convert|750|LT|t|0}} of [[fuel oil]], but could carry a maximum of {{convert|3160|LT|t|0}}. At full capacity, they could steam for an estimated {{convert|6000|nmi|-1}} at a speed of {{convert|20|knots}}.<ref name=b06>Burt, p. 306.</ref>

=== Armament ===
The ''Courageous''-class ships mounted four [[BL 15 inch Mk I naval gun|BL 15-inch Mark I]] guns in two twin hydraulically powered Mark I turrets, one each fore (designated the 'A' turret) and aft (the 'Y' turret).<ref name=b06/> These turrets were originally intended for a {{sclass|Revenge|battleship|2}} that was canceled shortly after the war began.<ref>Burt, pp. 291, 308.</ref> The guns could be depressed to −3° and elevated to 20°; they could be loaded at any angle up to 20°, although loading at high angles tended to slow the gun's return to battery (firing position). The ships carried 120 shells per gun. They fired {{convert|1910|lb|kg|adj=on|0}} projectiles at a [[muzzle velocity]] of {{convert|2575|ft/s|m/s|abbr=on}}; this provided a maximum range of {{convert|23734|yd|abbr=on|0}} with [[Armor-piercing shot and shell|armour-piercing]] shells.<ref>{{cite web | url = http://www.navweaps.com/Weapons/WNBR_15-42_mk1.htm | title = British 15"/42 (38.1 cm) Mark I | date = 1 April 2010 | access-date = 4 May 2010 | publisher = NavWeaps.com }}</ref>

[[File:HMS Furious-1.jpg|thumb|''Furious'' had a single 18-inch gun fitted]]
The ''Courageous''-class ships were designed with 18 [[BL 4 inch Mk IX naval gun|BL 4-inch Mark IX guns]], fitted in six triple mounts. These were manually powered and quite cumbersome in use as they required a crew of thirty-two men to load and train the guns. The gun's rate of fire was only 10 to 12 rounds per minute as the loaders kept getting in each other's way. They had a maximum depression of −10° and a maximum elevation of 30°. They fired a {{convert|22|lb|kg|adj=on}} [[Explosive material#High explosives|high explosive]] shell at a muzzle velocity of {{convert|2625|ft/s|m/s|abbr=on}}. At maximum elevation the guns had a maximum range of {{convert|13500|yd|m|0}}.<ref>{{cite web | url = http://www.navweaps.com/Weapons/WNBR_4-45_mk9.htm | title = Britain 4"/45 (10.2 cm) BL Marks IX and X | date = 25 January 2010 | access-date = 7 May 2010 | publisher = NavWeaps.com | archive-url = https://web.archive.org/web/20120217005213/http://navweaps.com/Weapons/WNBR_4-45_mk9.htm | archive-date = 17 February 2012 | url-status = dead }}</ref> The ships carried 120 rounds for each gun.<ref name=b06/>

Each ship mounted a pair of [[QF 3 inch 20 cwt]]<ref group="Note">"cwt" is the abbreviation for [[hundredweight]], 30 cwt referring to the weight of the gun.</ref> [[Anti-aircraft warfare|anti-aircraft]] guns on single high-angle Mark II mountings. These were mounted abreast the mainmast in the ''Courageous''-class ships and before the funnel on ''Furious''.<ref name=b06/> The gun had a maximum depression of 10° and a maximum elevation of 90°. It fired a {{convert|12.5|lb|kg|adj=on}} shell at a muzzle velocity of {{convert|2500|ft/s|m/s|abbr=on}} at a rate of fire of 12–14 rounds per minute. They had a maximum effective ceiling of {{convert|23500|ft|m|abbr=on}}.<ref>{{cite web | url = http://www.navweaps.com/Weapons/WNBR_3-45_mk1.htm | title = British 12-pdr <nowiki>[3"/45 (76.2 cm)]</nowiki> 20 cwt QF HA Marks I, II, III and IV | date = 27 February 2007 | access-date = 11 November 2009 | publisher = NavWeaps.com }}</ref> All three ships carried ten [[torpedo]]es and mounted two [[British 21 inch torpedo|{{convert|21|in|adj=on|0}}]] submerged side-loading [[torpedo tube]]s fitted near 'A' turret. They were loaded and traversed by hydraulic power, but fired by compressed air.<ref>Roberts, p. 83.</ref>

The [[BL 18 inch Mk I naval gun|18-inch BL Mark I gun]] carried by ''Furious'' was derived from the 15-inch Mark I gun used in her half-sisters. It was intended to be mounted in two single-gun turrets derived from the twin-gun 15-inch Mark I/N turret, and her barbettes were designed to accommodate either turret in case problems arose with the 18-inch gun's development, but only one turret was actually fitted. The gun could depress to −3° and elevate to a maximum of 30°. It fired a {{convert|3320|lb|kg|adj=on}}, 4 [[List of British ordnance terms#C.R.H.|crh]] [[Armor-piercing shot and shell|armour-piercing, capped]] shell at a [[muzzle velocity]] of {{convert|2270|ft/s|m/s|abbr=on}} to a distance of {{convert|28900|yd|m}}. It could fire one round per minute and the ship carried sixty rounds of ammunition. The turret's revolving mass was {{convert|826|LT|0}}, only slightly more than the {{convert|810|LT|0}} of its predecessor.<ref>{{cite web | url = http://www.navweaps.com/Weapons/WNBR_18-40_mk1.htm | title = British 18"/40 (45.7 cm) Mark I | date = 22 October 2009 | access-date = 10 May 2010 | publisher = NavWeaps.com }}</ref>

''Furious''{{'}}s secondary armament consisted of 11 BL 5.5-inch Mk I guns. The guns had a maximum elevation of 25° on their pivot mounts. They fired {{convert|82|lb|kg|adj=on}} projectiles at a muzzle velocity of {{convert|2790|ft/s|m/s|abbr=on}} at a rate of 12 rounds per minute. Their maximum range was {{convert|16000|yd|m|abbr=on}} at 25° elevation.<ref name=nav>{{cite web | url = http://www.navweaps.com/Weapons/WNBR_55-50_mk1.htm | title = British 5.5"/50 (14 cm) BL Mark I | date = 23 January 2009 | access-date = 7 May 2010 | publisher = NavWeaps.com }}</ref>

=== Fire control ===
The main guns of the ''Courageous''-class ships could be controlled from either of the two [[Fire-control system#Naval fire control|fire-control directors]]. The primary director was mounted above the [[conning tower]] in an armoured hood and the other was in the [[Top (sailing ship)|fore-top]] on the foremast.<ref>Roberts, p. 93.</ref> The secondary armament was also director-controlled.<ref>McBride, p. 106.</ref> Each turret was provided with a {{convert|15|ft|m|1|adj=on}} rangefinder in an armoured housing on the turret roof. The fore-top was equipped with a {{convert|9|ft|m|adj=on|1}} rangefinder as was the torpedo control tower above the rear superstructure. The anti-aircraft guns were controlled by a simple {{convert|2|m|ftin|adj=on}} rangefinder mounted on the aft superstructure.<ref>Burt, p. 307.</ref>

=== Protection ===
Unlike on other British battlecruisers, the bulk of the armour of the ''Courageous''-class ships was made from high-tensile steel, a type of steel used structurally in other ships. Their waterline [[Belt armor|belt]] consisted of {{convert|2|in|0}} covered by a {{convert|1|in|0|adj=on}} skin. It ran from barbette to barbette with a one-inch extension forward to the two-inch forward [[bulkhead (partition)|bulkhead]] well short of the bow. The belt had a height of {{convert|23|ft|m|1}}, of which {{convert|18|in|m|1}} was below the designed waterline. From the forward barbette a three-inch bulkhead extended out to the ship's side between the upper and lower decks and a comparable bulkhead was in place at the rear barbette as well. Four decks were armoured with thicknesses varying from {{convert|.75|to|3|in}}, with the greatest thicknesses over the magazines and the steering gear. After the loss of three battlecruisers to magazine explosions during the [[Battle of Jutland]], {{convert|110|LT|t|0}} of extra protection was added to the deck around the magazines.<ref>Burt, pp. 308, 313.</ref>

The turrets, barbettes and conning tower were made from [[Krupp cemented armour]]. The turret faces were {{convert|9|in|0}} thick while their sides ranged from {{convert|7|to|9|in|0}} in thickness and the roof was {{convert|4.5|in|0}} thick. The barbettes had a maximum thickness of {{convert|6|to|7|in|0}} above the main deck, but reduced in thickness to {{convert|3|to|4|in|0}} between the lower and main decks. The conning tower armour was {{convert|10|in|0}} thick and it had a three-inch roof. The primary fire-control director atop the conning tower was protected by an armoured hood. The face of the hood was six inches thick, its sides were two inches thick and its roof was protected by three inches of armour. A communications tube with three-inch sides ran from the conning tower down to the lower conning position on the main deck. The [[torpedo bulkhead]]s were increased during building from {{convert|.75|in}} to {{convert|1.5|in}} in thickness.<ref>Roberts, pp. 54, 106, 113.</ref>

All three ships were fitted with a shallow [[anti-torpedo bulge]] integral to the hull which was intended to explode the torpedo before it hit the hull proper and vent the underwater explosion to the surface rather than into the ship. However, later testing proved that it was not deep enough to accomplish its task as it lacked the layers of empty and full compartments that were necessary to absorb the force of the explosion.<ref>Roberts, p. 111.</ref>