The Orion-class battleships were a group of four dreadnought battleships built for the Royal Navy (RN) in the early 1910s. The first battleships built for the RN, they were much larger than the preceding British dreadnoughts and were sometimes termed "super-dreadnoughts". The sister ships spent most of their careers assigned to the 2nd Battle Squadron of the Home and Grand Fleets, sometimes serving as flagships. Aside from participating in the failed attempt to intercept the German ships that had bombarded Scarborough, Hartlepool and Whitby in late 1914, the Battle of Jutland in May 1916 and the inconclusive action of 19 August, their service during World War I generally consisted of routine patrols and training in the North Sea.
The Orions were deemed obsolete by the end of the war in 1918 and were reduced to reserve the following year. and were sold for scrap in 1922 while was hulked for use as a stationary training ship. In late 1923, she was converted into a target ship and was sunk in early 1925. served the longest, acting as a training ship from 1921 until she, too, was sold for scrap in late 1926. While being towed to the scrapyard, the ship ran aground; Thunderer was refloated and subsequently broken up.
Background and design
The initial 1909–1910 Naval Programme included two dreadnoughts and a battlecruiser, but was later increased to six dreadnoughts and two battlecruisers as a result of public pressure on the government due to the Anglo-German naval arms race. The original pair of battleships became the and were improved versions of the preceding battleship, . A third dreadnought was added to the programme around April 1909 that was to be armed with more powerful weapons than the guns used in the earlier dreadnoughts. Three more ships of this class, as well as another battlecruiser, were part of the contingency programme authorized in August.
Unlike all of the previous dreadnoughts, which had been incremental improvements of the original design of 1906, constrained by cost and size limits, the Orion class were almost a "clean-slate" design driven by the need to accommodate the larger guns and additional armour. The guns were positioned all on the centreline of the hull in superfiring gun turrets, an arrangement first used in HMS Neptune for the aft main turrets. The idea had been pioneered by the United States Navy in their , but the RN was slow to adopt the concept, concerned about the effects of muzzle blast on the gunlayers in the open sighting hoods in the roofs of the lower turrets.
One of the few things retained from earlier ships was the position of the tripod foremast with its spotting top behind the forward funnel to allow the vertical leg to be used to support the boat-handling derrick. This all but guaranteed that the hot funnel gases could render the spotting top uninhabitable at times, but the Board of Admiralty insisted on it for all the ships of the 1909–1910 Programme. David K. Brown, naval architect and historian, commented on the whole fiasco: "It is amazing that it took so long to attain a satisfactory arrangement, which was caused by the Director of Naval Ordnance (DNO)'s insistence on sighting hoods in the roofs of turrets and Jellicoe's obsession with boat-handling arrangements. These unsatisfactory layouts reduced firepower, prejudiced torpedo protection and probably added to cost. As DNO and then as Controller, Jellicoe must accept much of the blame for the unsatisfactory layout of the earlier ships."
Description
The Orion-class ships had an overall length of , a beam of , a normal draught of and a deep draught of . They displaced at normal load and at deep load. Their crew numbered 738 officers and ratings upon completion and 1,107 in 1917.
The ships retained the three engine-room layout of the Colossus-class design. They were powered by two sets of Parsons direct-drive steam turbines. The outer propeller shafts were coupled to the high-pressure turbines in the outer engine rooms and these exhausted into low-pressure turbines in the centre engine room which drove the inner shafts. The turbines used steam provided by 18 water-tube boilers. They were rated at and were intended to give the battleships a maximum speed of . During their sea trials, the Orions exceeded their designed speed and horsepower. They carried a maximum of of coal and an additional of fuel oil that was sprayed on the coal to increase its burn rate. This gave them a range of at a cruising speed of .