Editing Duncan-class battleship (section)

==Design==
[[File:Peresvet1901.jpg|thumb|left|{{ship|Russian battleship|Peresvet||2}}, the Russian battleship the ''Duncan''s were ordered to counter]]

The six ships of the ''Duncan'' class were ordered in response to Russian {{sclass|Peresvet|battleship|1}}s that began construction in the mid-1890s. At the time, the British mistakenly believed the Russian vessels were capable of a top speed of {{convert|19|kn|lk=in}} (though they were not that fast in service), so the [[Director of Naval Construction]], [[William Henry White]], set about designing a British response. His initial proposals were completed by February 1898, but the [[Board of Admiralty]] decided that more work would be required on the new ships, and so modified versions of the preceding {{sclass|Formidable|battleship|4}} would be ordered in the meantime. These ships incorporated some of the aspects of White's design, namely the revised armour protection layout in the bow, which abandoned the heavy transverse [[bulkhead (partition)|bulkhead]] that connected both ends of the [[armoured belt]] in favour of continuing the side armour all the way to the [[stem (ship)|stem]], albeit at reduced thickness; these became the five {{sclass|London|battleship|1}}s. White then returned to working on the design for the response to ''Peresvet'', completing a revised version on 14 June 1898.{{sfn|Burt|p=227}}

To achieve the desired speed of 19&nbsp;knots while keeping [[displacement (ship)|displacement]] about {{convert|1000|t|LT|lk=on}} less than the ''Formidable''s and retaining the same battery of four [[Armstrong Whitworth 12 inch /40 naval gun|{{convert|12|inch|adj=on|0}} guns]] carried by earlier British battleships, White was forced to make significant reductions, particularly in terms of armour protection. As such, they represented an evolution of the smaller {{sclass|Canopus|battleship|4}}, rather than a direct development of the ''Formidable'' or ''London'' types. The ''Duncan'' class was about a thousand tons heavier than the ''Canopus'' class, and with that increase in displacement, they acquired more powerful guns, heavier armour, and an improvement in top speed by one to two knots. Despite these improvements, the ''Duncan''s proved to be disappointments in service, owing to their reduced defensive characteristics, which rendered them inferior to the true first class battleships to which they were inevitably compared. Nevertheless, they were still markedly superior to the ''Peresvets'' they had been built to counter, and they were some of the fastest battleships in service at the time they were built.{{sfn|Burt|pp=227–229}}

Minor revisions to the dimensions were made between June and September, when the finalised design was approved, with tenders for shipyard contracts being sent out the following month. Public pressure over the 1898 programme—the first three ''London''s that were supposedly slower than the ''Peresvet''s—led to the passage of a Special Supplementary Programme that allocated funding for the first four ''Duncan''s, all of which were laid down in 1899. Two more were added under the 1899 programme.{{sfn|Burt|pp=227–228}}

===General characteristics and machinery===
[[File:Duncan class diagrams Brasseys 1915.jpg|thumb|left|Right elevation and deck plan as depicted in ''Brassey's Naval Annual 1915'']]

The ''Duncan''-class ships were {{convert|432|ft}} [[length overall|long overall]], with a [[beam (nautical)|beam]] of {{convert|75|ft|6|in|abbr=on}} and a [[draft (hull)|draft]] of {{convert|25|ft|9|in|abbr=on}}. The ''Duncan''-class battleships displaced {{convert|13270|to|13745|LT}} [[normal displacement|normally]] and up to {{convert|14900|to|15200|LT}} [[full load|fully loaded]]. They had two pole masts fitted with [[fighting top]]s; each top carried a [[searchlight]], and four additional searchlights were mounted on the forward and aft [[Bridge (nautical)|bridges]].{{sfn|Lyon & Roberts|p=37}} The ships' hulls were divided with longitudinal bulkheads that should have allowed for counter-flooding to offset underwater damage, but the equipment necessary to quickly flood a compartment was insufficient, as was typical in many British pre-dreadnought designs. The decision to adopt longitudinal bulkheads was made in large part to keep [[secondary stability|reserve stability]] low, since that made the ships more stable gun platforms.{{sfn|Burt|p=236}}

Their crew numbered 720&nbsp;officers and [[Naval rating|ratings]], though this varied over the course of their careers; in 1904, ''Russell'' had a crew of 736, and while serving as a [[flagship]] that same year, ''Exmouth'' had a crew of 762. During the [[First World War]] in 1915, ''Russell''{{'}}s crew had grown to 781. The ships were fitted with Type 1 [[wireless telegraphy]] sets, with the exception of ''Exmouth'', which received Type 2 sets. The remainder of the class had their Type 1s replaced with Type 2 sets later in their career, except for ''Montagu'', which had already been wrecked by that time. ''Cornwallis'' and ''Russell'' eventually received Type 3 wireless transmitters. The ships carried a number of small boats that varied over the course of their careers, including a variety of steam and sail [[Pinnace (ship's boat)|pinnaces]], steam [[Launch (boat)|launches]], [[Cutter (boat)|cutters]], [[whaler]]s, [[Captain's gig|gigs]], [[dinghy|dinghies]], and [[raft]]s.{{sfn|Lyon & Roberts|p=37}}{{sfn|Burt|pp=232–233}}

The ''Duncan''-class ships were powered by a pair of 4-cylinder [[triple-expansion engine]]s that drove two inward-turning, four-bladed [[propeller|screws]]. Steam was provided by twenty-four [[Belleville boiler]]s. The boilers were divided into four [[fire room|boiler rooms]], two of which contained eight boilers each and the other two with four boilers per room; they were trunked into two closely spaced [[funnel (ship)|funnels]] located [[amidships]]. The ''Duncan''-class ships had a top speed of {{convert|19|kn}} from {{convert|18000|ihp|lk=in}}, though on speed trials their maximum speed ranged from {{convert|18.6|to|19.4|kn}}, with power slightly exceeding the design figure.{{sfn|Lyon & Roberts|p=37}}{{sfn|Burt|p=236}} At a cruising speed of {{convert|10|kn}}, the ship could steam for {{convert|6070|nmi|lk=in}}.{{sfn|Burt|p=232}}

===Armament===
[[File:Gun Shop in Armstrong Works LOC ggbain 00178.jpg|thumb|The two turrets for ''Cornwallis'' under construction]]
The ''Duncan''s had four 12-inch 40-calibre guns mounted in twin-[[gun turret]]s fore and aft. These were the same guns and mountings carried aboard the ''Formidable'' and ''London'' classes, although their [[barbette]]s were reduced in diameter as a weight-saving measure. To account for the slightly narrower barbettes, the gun houses also had to be reduced in size, though the guns were carried in the same BVI-type mountings.{{sfn|Burt|pp=229, 231}} The mounts had a range of elevation from -5&nbsp;degrees to of 13.5&nbsp;degrees, and required the guns to return to 4.5&nbsp;degrees to be loaded. The guns had a muzzle velocity of {{convert|2562|to|2573|ft/s}}, and they were capable of penetrating 12 inches of Krupp armour at a range of {{convert|4800|yd}}. At their maximum elevation, the guns had a range of {{convert|15300|yd}}.{{sfn|Friedman|pp=57–58}}

The ships also mounted a [[secondary armament|secondary battery]] of twelve {{convert|6|in|mm|adj=on|0}} 45-calibre guns mounted in [[casemate]]s, the same battery carried by earlier British battleships. The casemates were [[sponson]]ed further out from the sides of the hull, however, to improve their firing arcs while reducing blast effects on the hull when the guns fired ahead or astern. The designers considered moving two of the guns per side to the upper deck to improve their fighting capabilities in heavy seas, but decided that such an arrangement would hamper ammunition movement from the magazines.{{sfn|Burt|pp=231, 233}} The guns had a muzzle velocity of {{convert|2536|ft/s|abbr=on}}. These guns could penetrate six inches of Krupp armour at {{convert|2500|yd}}. Maximum elevation was 14&nbsp;degrees, which allowed the guns to engage targets out to {{convert|12000|yd}}.{{sfn|Friedman|pp=79–81}} For defence against [[torpedo boat]]s, they carried ten 12-pounder guns and six 3-pounder guns. As was customary for battleships of the period, they were also equipped with four [[British 18 inch torpedo|{{convert|18|in|mm|adj=on|0}} torpedo]] tubes submerged in the [[hull (watercraft)|hull]].{{sfn|Lyon & Roberts|p=37}}

In 1915, the five surviving ships received two {{convert|3|in|adj=on}} [[anti-aircraft gun]]s. ''Albemarle'', ''Duncan'', and probably ''Exmouth'' had theirs installed on their aft [[superstructure]], while ''Russell'' had hers mounted on her [[quarterdeck]] and ''Cornwallis'' had her guns placed atop their forwardmost casemates. Between 1916 and 1917, ''Albemarle'' had her casemate guns removed, with four of the 6-inch guns being relocated to the 12-pounder battery and two of those guns being removed to make room. The 6-inch guns were placed in shielded pivot mounts. In 1917–1918, ''Albemarle'' had the rest of her 12-pounders removed altogether.{{sfn|Burt|p=242}}

===Armour===
The ''Duncan'' class adopted the basic armour layout of the ''Formidable'' class, but with significant revision to the forward armour scheme and with significantly thinner levels of protection. Earlier battleship designs had employed a partial armoured belt that terminated abreast of both of the main battery turrets; the ends of the belt were connected by way of transverse bulkheads to create a central citadel that protected the ships' magazines and propulsion machinery spaces. This arrangement left the bow and stern unprotected, and thus highly vulnerable to enemy fire. White was concerned that the unprotected bow could be flooded by even light gunfire, which would reduce speed and maneuverability. Since the ''Duncan''s were intended to serve as fast battleships, White decided to reduce the risk of this kind of damage by discarding the forward transverse bulkhead in favor of a complete belt. The main portion of the belt was {{convert|7|in|0}} thick and extended to just forward of the fore turret, thereafter being gradually reduced to {{convert|5|in|0|abbr=on}}, then {{convert|4|in|0|abbr=on}}, then to {{convert|3|in|0|abbr=on}}, and finally to {{convert|2|in|0|abbr=on}} close to the stem. The aft end of the ship retained the traditional transverse bulkhead, which was also 7&nbsp;in thick. Abaft of the bulkhead, the hull was protected by a [[strake]] of {{convert|1|in|adj=on}} thick side armour.{{sfn|Burt|pp=234–235}}

Horizontal protection consisted of a pair of armoured decks that covered the ships' vitals. The main deck ran from the stem to the aft bulkhead and was connected to the top of the belt; it was 1 to 2&nbsp;in thick, with the thicker armour over the central portion of the ship and the thinner steel over the bow. The second deck, at middle deck level, was 1&nbsp;in thick and covered just the central citadel, sloping down on the sides to the belt. The voids created between the decks and behind the belt were used to store coal, which had the added benefit of increasing the strength of the side protection layout. The bow and stern had a curved armour deck below the waterline that extended from the barbettes to either end of the hull, which was 1 to 2&nbsp;in thick. The ships' main battery turrets faces and sides were {{convert|8|in|0|abbr=on}} thick, with {{convert|10|in|abbr=on|0}} rears and 2–3&nbsp;in roofs. The turrets sat atop barbettes that were {{convert|11|in|abbr=on|0}} on the outer face above the belt and 7&nbsp;in thick behind the belt; their inner faces were reduced to 10 and 4&nbsp;inches thick, respectively. The casemate battery was protected with {{convert|6|in|abbr=on|0}} of armour plate, and their ammunition hoists received 2&nbsp;in of armour protection. The ships' forward [[conning tower]]s had 10–12&nbsp;in sides and their aft conning towers had 3&nbsp;in sides.{{sfn|Burt|pp=235–236}}