Devastation class battleship

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General Characteristics

Displacement:	9188 tons
Length:	87 m (285 ft)
Beam:	19 m (62 ft 3 inches)
Draught:	Maximum 8.4 m (27 ft 6 inches)
Propulsion:	Two coal fired Penn trunk engines, 2 screws;
Speed:	13 knots (24 km/h) maximum
Range:	8700 km (4700 miles)
Complement:	410
Armament:	Four 30 cm (12 inch) rifled muzzle-loading guns mounted in two turrets
Armour:	38 cm (15 inch) armour on turrets, 30 cm (12 inches) partial belt reducing to 25 cm (10 inches) at ends, 7.6 cm (3 inch) curved deck

The two British Devastation-class battleships of the 1870s were the first class of ocean-going capital ship which did not carry sails, and the first which mounted the entire main armament on top of the hull rather than inside it. For the first fifteen years of their lives, they were the most powerful warships in the world.

The genesis of the design was a request by the First Lord of the Admiralty Hugh Childers to the head of ship design at the Admiralty, Edward Reed in early 1869 for a large breastwork monitor which could steam from Queenstown (now Cobh) in Ireland to Halifax in Canada.

He responded in February 1869 with an outline design, but complained that the upper limit on displacement of 3000 tons was insufficient and suggested that 4000 tons was more practical. At a meeting shortly afterwards of the Admiralty board it was agreed that the ship should have two 30 cm (12 inch) guns firing 275 kg (600 pound) shells mounted in each of two turrets protected by 35 cm (14 inches) of armour, which would each have a 280 degree field of fire. The turrets would be mounted on the centre-line one of which would be in front of the superstructure and one behind it. The ship would be protected by a 30 cm (12 inch) thick armour belt around the waterline.

A very low freeboard of 1.4 m (4 feet 6 inches) was agreed since the ship was now intended for coastal service in waters around the United Kingdom or service in the relatively calm Mediterranean. Twin steam engines and twin screws were felt necessary for security, and there was a strong feeling that masts and sails should be dispensed with. This was in part due to problems with masted turret warships, where the standing rigging for the masts interfered with the field of fire of the turrets, but their absence meant that the vessel could not operate far away from friendly coaling stations.

A replica of the proposed turret was constructed and tested at Shoeburyness in May 1872. The 28 cm (11 inch) armour plate backed by 38 cm (15 inches) of teak and a 3.2 cm (1.25 inch) metal skin resisted hits from a 25 ton gun firing at a range of 180 m (200 yards), although one shot hit a joint between plates and opened a gap 18 cm (7 inches) wide but did not penetrate.

The main belt was 30 cm (12 inches) of armour reducing to 25 cm (10 inches) at the ends, and backed by 46 cm (18 inches) of teak.

The loss of HMS Captain in 1870 led to concerns about the stability of turret ships, and a committee was set up to determine whether Devastation would be safe. One effect of this was to extend the armoured breastwork with unarmoured structure to the sides of the ship and carried aft to improve the stability at large angles of heel. This greatly improved the crew comfort by adding extra accommodation and especially latrines, but since it was not armoured would have been riddled in a battle reducing the stability of the vessel.

In 1871 a 2.75 m (9 feet) long model of Devastation was tested in a water tank, and subsequently with an 5.5 m (18 feet) long version. Once Devastation was completed, tests could be carried out with the real ship. This included building up a roll of 7 degrees by having 400 men run backwards and forwards across the deck 18 times. Other tests involved taking it to sea to look for rough weather, in one trial waves of 6-8 m (20-26 feet) were encountered which gave the ship a 14 degree roll either way.