page_title: Formidable-class battleship
section_title: Design
hierarchical_section_title: Formidable-class battleship / Design
caption_attribution_description: English: Right elevation and deck plan depicting British Formidable class battleship. Top diagram (right elevation) shows armour thickness in inches. Bottom diagram (deck plan) shows gun sizes in inches.
context_page_description: The Formidable class of battleships were a three-ship class of pre-dreadnoughts designed by Sir William White and built for the Royal Navy in the late 1890s. The class comprised Formidable, Irresistible, and Implacable. They were armed with a battery of four 12-inch guns, they had top speed of 18 knots, and they marked the adoption of Krupp armour in British battleship designs. The class formed the basis for the nearly identical London class of five ships, and those ships are sometimes included in the Formidable class. Formidable, Irresistible, and Implacable were built between 1898 and 1901 at the Portsmouth, Chatham, and Devonport Dockyards, respectively.
  All three ships served in the Mediterranean Fleet early in their careers, before returning to British waters in the late 1900s for duty in the Home Fleet, Channel Fleet, and the Atlantic Fleet. By 1912, all three ships had been assigned to the 5th Battle Squadron, Home Fleet, where they remained until the outbreak of the First World War in August 1914.
context_section_description: Design work on what became the Formidable class began with a meeting of the Board of Admiralty on 3 May 1897, where the general parameters of the new class was discussed. The Board concluded that repeating the Canopus class would not be a workable solution, since the Imperial Japanese Navy had begun building larger, 15,000-tonne (15,000-long-ton; 17,000-short-ton) battleships and the Canopus design was too small to carry the new 40-calibre 12-inch (305 mm) Mk IX guns, which were significantly heavier than the shorter 35-calibre BL 12-inch Mk VIII guns. The design staff determined that it was possible to construct a new ship that incorporated the advances of the Canopus class—namely, Krupp armour and improved engines and water-tube boilers—on a larger hull like the earlier Majestic-class battleships without increasing displacement and keeping the same speed as the Canopus class.
  The Director of Naval Construction, William Henry White, provided two design options, both modified versions of the basic Majestic form. Both variants had a main battery of four 12-inch guns, belt armour that was 8 inches (203 mm) thick, and a top speed of 18 knots (33 km/h; 21 mph). The main difference between the designs was the number of secondary guns; the first had twelve 6 in (152 mm) guns and the second had fourteen of the guns. Displacement differed by just 200 tons, at 14,700 t (14,500 long tons; 16,200 short tons) for the 12-gun variant and 14,900 t (14,700 long tons; 16,400 short tons) for the other one. White preferred the 14-gun version, though the consensus of the Board was that twelve guns were sufficient, on the basis that the two additional guns would overcrowd the upper deck, where they would have been placed, and would have increased the size of the crew too much. Additionally, a secondary battery of twelve guns was deemed to be sufficient in comparison to most other foreign battleships. And while an increase in offensive power would have been welcome, members of the Board decided that the weight savings gained by omitting the two guns could be used to strengthen the ships' armour, which they preferred at a time where naval guns were becoming increasingly powerful.
  The board adopted the 12-gun version, along with a request to increase the belt to 9 inches (229 mm). The thicker armour increased displacement to 15,000 t (15,000 long tons). The board requested that White prepare drawings for this new design on 19 June. A model was created by 17 August, which allowed the design staff to refine the hull shape. The staff cut away the deadwood forward and aft, which made the vessels more handy. Due to their similarity, some like historian Tony Gibbons consider the five London-class battleships to be part of the Formidable class, though most historians view them as a distinct class. The five London-class ships differed from the Formidables in their protection layout, which abandoned the forward armoured bulkhead in favour of an armoured belt that extended all the way to the stem. Regardless, the Formidable design provided the basis for the five Londons that were ordered under the 1898 programme.
caption: Right elevation and deck plan as depicted in Brassey's Naval Annual 1906
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