Lord Nelson Class Battleship - Technical Characteristics

Technical Characteristics

The Lord Nelson-class battleships were designed and built at a time when the direction of future battleship construction was controversial. On the one hand, naval combat during the Russo–Japanese War of 1904–1905 suggested that engagement ranges would increase to the point that intermediate and secondary batteries would become far less important and perhaps even ineffective, and that smaller-calibre guns would be useless in combat between capital ships; on the other hand, the lower rate of fire of battleship main batteries raised questions about the prudence of building all-big-gun battleships, for fear that they might be overwhelmed by the higher rate of fire of intermediate-calibre guns in the shorter-range engagements that might occur in fog or bad weather or at night. In the end, the all-big-gun battleships, which became known as dreadnoughts after the first such ship, HMS Dreadnought, were vindicated, but this was by no means clear when the Lord Nelsons were designed in 1904 or even by the time they were laid down in 1905.

The Lord Nelsons were the first battleships for which Sir Phillip Watts was responsible. Although they followed the pre-dreadnought pattern established in the Royal Sovereign-class battleships in the early 1890s of having two twin main battery mounts, one fore and one aft, and mounted a main battery of four 12 inch (305 mm) guns, as had every pre-dreadnought since those of the Majestic-class battleship in the mid-1890s, they otherwise were a major departure from previous British pre-dreadnought designs; they might have marked a new era in pre-dreadnought design had not the rise of the dreadnoughts snuffed out the pre-dreadnought era. In order to match increases in firepower seen in foreign battleships of similar displacement, the preceding King Edward VII-class battleships had introduced a 9.2-inch (234 mm) intermediate battery into British battleships in addition to the 6 inch (152 mm) secondary battery they long had mounted, but the Lord Nelsons carried this further by mounting an all-9.2-inch secondary battery; they were the first British battleships not to mount 6 inch guns since HMS Inflexible, which joined the fleet in 1881. (The Trafalgar and Centurion classes had joined the fleet with 4.7 inch (120 mm) secondaries but had later had them replaced by 6 inch guns.) Also, the 9.2-inch battery, made up of more powerful guns than on the King Edward VII-class ships, was mounted in turrets (four double and two single) on the upper deck, rather than on the main deck in a central battery or casemates; this eliminated the problem of being unable to work the secondaries in a seaway, a problem in the many classes of British battleships with main-deck-mounted secondaries which were washed out in all but the calmest weather.

The 12 inch guns were a new, more powerful, 45-calibre type; they and their turrets were the same as those carried by the revolutionary Dreadnought; indeed, the completion of Lord Nelson and Agamemnon was delayed when their main battery guns and mountings were diverted to Dreadnought to expedite her completion in 1906.

In the end, the mixed-calibre heavy armament proved unsuccessful, as gunnery officers found it impossible to distinguish between 12-inch (305-mm) and 9.2-inch shell splashes, making fire control impractical. This finding further pushed the navies of the world to move to all-big-gun dreadnought battleship designs. Indeed, an all-big-gun design had been considered for the Lord Nelsons in January 1905, but their design was too far advanced by then to be changed, and the all-big-gun layout had to await HMS Dreadnought.

For anti-torpedo-boat defense, the Lord Nelsons retained a battery of 12-pounders. These were mounted on a large flying deck amidships, where they had good command. However, this innovative mounting scheme also was criticised because it made a good target and because falling debris due to damage might foul the 9.2-inch turrets below in combat. In addition, some officers believed that the all-12-pounder battery was too light to deal with larger, modern torpedo boats.

Larger gun calibres becoming common in foreign battleships, it was also recognised that greater protection was needed than had been thought to be the case in previous classes, and their main armour belt was twelve inches thick over the machinery spaces and magazines; the armour belt in the King Edward VII-class battleships, the immediately preceding class, was nowhere more than nine inches (229 mm) thick. The deletion of the casemate armour required for the 6 inch guns formerly mounted allowed the main belt armour to be increased at very little cost in weight. They were more heavily armoured than any other British pre-dreadnoughts, and more heavily armored in terms of area and thickness than any of the dreadnoughts prior to the Orion-class of 1909. They were the first British battleships to have solid watertight bulkheads, penetrated by no doors or pipes, intended to contain flooding, with access across the bulkheads being via lifts (elevators). The solid bulkheads proved unpopular in service because of the inconvenience they imposed on the crew and were not repeated in the early British dreadnoughts, although Russian experience in the Russo–Japanese War suggested that such bulkheads were useful in keeping pre-dreadnoughts from sinking. As further protection, each compartment in the Lord Nelsons had its own ventilation and pumping arrangements, eliminating the need for a single main drainage system as employed in previous British battleships and seen as a possible weakness during flooding.

Both ships were designed to be short because the design board responsible for the ships wanted them to be able to fit into dry docks otherwise closed to previous battleship classes. The design requirements this imposed made them shorter than the earlier King Edward VII-class battleships and rather cramped in service, but the requirements also made the ships both flat-sided and fairly flat-bottomed; this and the mounting of the heavy 9.2 inch guns and their turrets had the useful side-effect of making the Lord Nelsons resistant to rolling and therefore both good seaboats and good gun platforms. However, the design also forced a compromises in the 9.2-inch battery. The ships' beam limitations forced abandonment of a design in which each of them would mount twelve 9.2 inch guns in six twin turrets, and instead they mounted ten of the guns in four twin and two single turrets, and limitations on the size of the 9.2-inch turrets themselves meant that they were cramped enough in service to impair the rate of fire of their guns.

They were the last British battleships to have reciprocating engines and the last with twin propellers, future classes having turbines and four propellers. They also were the last with inward-turning screws, which allowed greater propulsive force and slightly higher speeds and slightly less fuel consumption, but were unpopular in service because they made ships less manoeuvrable at low speeds or when going astern. It was decided to stop using mixed boiler types in the same ship, and both had 15 uniform, large water-tube boilers, Babcock and Wilcox in Lord Nelson and Yarrow in Agamemnon. Although primarily coal-powered, they were the first British battleships designed to carry oil, earlier ships having been retrofitted to carry oil; Lord Nelson had six oil spayers and Agamemnon five, and the use of these extended their range considerably. The boiler arrangements were very successful in service, and both ships easily made their design speed of 18 knots (33.33 km/h); on trials Lord Nelson made 18.7 knots (34.6 km/h) and Agamemnon made 18.5 knots (34.25 km/h).

The Lord Nelsons were the last British battleships to have an armoured ram built into their bow. They cost just over £1,600,000 each, the 2005 equivalent of about £110,000,000. The ships as completed were homely but intimidating in appearance, and looked more like French battleships than the previous British pre-dreadnought pattern.