The Hawkins class consisted of five heavy cruisers built for the Royal Navy during the First World War, although none of them saw service during the war. The first ship to be completed, , was renamed from HMS Cavendish and converted into an aircraft carrier while under construction. All ships were named after Elizabethan sea captains. The three ships remaining as cruisers in 1939 served in the Second World War, with Effingham being an early war loss through wreck; Raleigh had been lost in a similar shipwreck on uncharted rocks in 1922 (and Vindictive was nearly lost to grounding in 1919). Vindictive, though no longer a cruiser, also served throughout the War. This class formed the basis for the definition of the maximum cruiser type under the Washington Naval Treaty of 1922.
Design
Although the Hawkins class are sometimes named as the "Improved Birminghams", referring to the Birmingham sub-class of the Town-class light cruisers, their design was based on a proposal by the Director of Naval Construction, Eustace Tennyson d'Eyncourt, in 1912–1913. Reacting to rumours of large German cruisers armed with guns for overseas service and the need to replace the elderly armoured cruisers deployed abroad, d'Eyncourt proposed an oil-fuelled and lightly armoured ship of capable of and armed with guns in turrets. Referring the design as a "Light Cruiser for Atlantic Service", he optimised the design for good seakeeping performance for hunting down commerce raiders by giving it a deep draught and high freeboard.Friedman 2010, p. 35
Winston Churchill, First Lord of the Admiralty, objected to the size and cost of the ship and asked for a smaller and faster design armed with a mix of and 7.5-inch guns, capable of using oil and a version of the new design using a mix of coal and oil as in the Birminghams in August 1913. The oil-fuelled design was estimated to cost £550,000, compared to the original's £700,000, while the mixed-fuel ship was priced at £590,000. Nothing further was done with the designs as the naval construction budget was already badly stretched.
In the early months of the First World War, German commerce-raiding warships and armed merchant cruisers seriously disrupted British seaborne trade as the need to form convoys or re-route ships to avoid areas that the raiders in which were operating seriously delayed sailings or lengthened voyages. Furthermore, the need to escort the convoys and to search for the raiders required large numbers of warships that were needed elsewhere, far out of proportion to numbers of raiders.Raven & Roberts, p. 51 On 12 October 1914 d'Eyncourt reiterated the arguments behind his "Atlantic Cruiser" proposal in a memo to the Board of Admiralty, adding that a fast mixed-fuel design with a large steaming radius would be very helpful for operations in remote areas where oil might not be available.Friedman 2010, p. 65
By early 1915 the threat had been neutralised or sunk, but the Royal Navy believed that further commerce-raiding operations were likely. On 9 June the board met to consider specifications for a large light cruiser capable of hunting down commerce raiders anywhere in the world. D'Eyncourt was subsequently requested to submit designs for a ship capable of with at least one-fifth power from coal-fired boilers and an armament of at least ten 6-inch guns. He submitted six sketch designs armed with various mixes of 6-, 7.5- and guns using and hulls.Friedman 2010, p. 65, fn. 33, p. 340 Based on several encounters where the raiders had attempted to flee as soon as they had spotted the cruisers, the board believed that the ship's armament needed to be able to reach out to the visible horizon and be powerful enough to cripple the raider with a single hit. It therefore rejected the 6-inch gun as too short-ranged and lacking in power and the 9.2-inch gun as too few could be mounted on the hull; settling on the 7.5-inch gun in a new mount capable of 30° of elevation to maximise its range and carried on the larger of the two hulls proposed. The fruition of this design meant that with the 1930 London Naval Treaty the Hawkins class would become the Royal Navy's first heavy cruisers.
Description
The ships had an overall length of , a beam of and a draught of at deep load.Preston, p. 63 They displaced at standard load and at deep load. The shape of the hull was based on that of the large light cruiser with anti-torpedo bulges covering the engine and boiler rooms. Amidships, the hull had 10° of tumblehome, although the forward portion of the forecastle deck flared outwards to improve sea keeping. The ships had a metacentric height of at deep load. D'Eyncourt claimed that they were so subdivided that they could survive the flooding of two adjacent compartments. Their crew numbered 37 officers and 672 ratings.Raven & Roberts, p. 404Friedman 2010, pp. 67, 390
The Hawkins class were equipped with four geared steam turbine sets, each driving one propeller shaft using steam provided by a dozen Yarrow boilers at a pressure of , distributed between three boiler rooms. The fore and aft groups adopted a modern oil-fired design, but the four boilers in the middle compartment were coal-fired, so that cruising fuel could be easily obtained in foreign ports where oil was not available. The drawback being that they produced much less power, only generating one-sixth of the ships' total output.Friedman 2010, pp. 65, 69 The steam from the boilers was ducted into two funnels, the uptakes from the coal-fired central group being split and trunked in with those from the oil-fired ones fore and aft.Raven & Roberts, p. 405Friedman 2010, p. 69 The turbines were rated at to give the ships a design speed of 30 knots. A fuel supply of of fuel oil and of coal was supposed to give a steaming range of at .Friedman 2010, p. 390
In the event, only Hawkins and Vindictive were completed with this engine installation. During her sea trials in 1919, Hawkins reached a speed of from about at deep load, a slightly disappointing figure as she had been designed for at this displacement.
In November 1917 the Admiralty decided to replace the coal-fired boilers in the three least-advanced ships with four oil-fired ones, but only Raleigh actually received this modification, which increased her power to for a theoretical . The following year, Raleigh reached her designed speed during her trials. Effingham and Frobisher exchanged their coal-fired boilers for a single pair of oil-fired boilers which gave them for a design speed of . These three ships stowed of oil which was designed to give them the same range of at . The ships' machinery arrangements would be further modified in later refits and reconstructions.
Armament The main armament of the Hawkins-class ships consisted of seven 45-calibre Mk VI guns in single mounts protected by gun shields. The guns fired projectiles at a muzzle velocity of to their maximum range of .Friedman 2011, pp. 78 The ships stowed 150 rounds per gun. The mounts were initially hand-worked, but they were refitted with power-operated elevation and traverse motors after the war. Powered-loading gear was never fitted and the guns could only be hand-loaded up to 10° elevation. The requirements for long lines of ammunition-handlers, physically passing rounds and cartridges along the deck from the shell-hoist to each gun (and in the case of the superfiring forward gun, physically passing them up from one deck to the next) were particularly inconvenient, and in terms of manpower, were described as "absurdly out of proportion" to the ship's cruiser role and firepower.
The ships were arranged with five guns on the centreline, four of which were in superfiring pairs fore and aft of the superstructure, the fifth gun was further aft on the quarterdeck, and the last two as wing guns abreast the aft funnel.Friedman 2010, p. 66 To make room for her flight decks, HMS Vindictive was completed with just four guns, one forward, two in the wing positions, and one right aft. Further revisions to the number and layout of the main guns would be made subsequently.
, and Hawkins had their guns controlled by a mechanical Mark I Dreyer Fire-control Table. It used data provided by the coincidence rangefinder in the pedestal-type gunnery director positioned under the spotting top at the head of the tripod mast. The ships were also fitted with one and a rangefinder. Effingham and Frobisher were fitted with a Mark III Dreyer Fire-control Table and three 12-foot rangefinders.
The secondary armament of the class was intended to consist of ten 20 cwt Mk I guns."Cwt" is the abbreviation for hundredweight, 20 cwt referring to the weight of the gun. Six of these were in low-angle mounts to defend against torpedo boat attack, two in casemates between the forward 7.5-inch guns, another pair on platforms abreast the conning tower and two on a platform between the funnels. The last four served as anti-aircraft (AA) guns and were positioned further aft around the base of the main mast. They fired shells at a muzzle velocity of .Friedman 2011, pp. 107–108 Each gun was provided with 300 rounds.
In practice, the secondary armament of each ship varied. At most, only Hawkins and Raleigh completed with the intended guns, and if so, they were promptly modified. No low-angle guns were fitted in Effingham or Frobisher and their high-angle guns were replaced by three Mk V guns on high-angle HA Mark III mountings. A pair of these were positioned at the base of the main mast and the third gun was on the quarterdeck.Raven & Roberts, p. 55 At an elevation of +30°, their shells had a range of at a muzzle velocity of .Friedman 2011, pp. 103–104 The rest of their anti-aircraft suite consisted of a pair of 2-pounder () AA guns that were added during construction. The Hawkins-class ships were designed with a submerged 21-inch (533 mm) torpedo tube on each broadside, but two above-water torpedo tubes were added below the base of the main mast during construction on each broadside.Friedman 2010, pp. 66–67; Raven & Roberts, p. 404
Armour The Hawkins class were protected by a full-length waterline armoured belt of high-tensile steel (HTS) that covered most of the ships' sides. It was thickest over the boiler and engine rooms, ranging from thick. Their magazines were protected by an additional of HTS. There was a 1-inch aft transverse bulkhead of mild steel and the conning tower was protected by 3-inch HTS plates. The ships' deck protection consisted of 1- to 1.5-inch HTS.
Cavendish as an aircraft carrier
In January 1917, the Admiralty reviewed the navy's aircraft carrier requirements and decided to order two ships fitted with a flying-off deck as well as a landing deck aft. The initial order had to be cancelled in April 1917 for lack of building facilities, so the Admiralty decided to convert Cavendish, already under construction, in June 1917. She was renamed Vindictive to perpetuate the name of the cruiser sunk at the Second Ostend Raid and her construction was rushed to bring her into service before her cruiser sisters.