Editing St Vincent-class battleship (section)

===Fire control===
[[File:St Vincent - NH 54835.jpg|thumb|''St Vincent'' at anchor, before 1912]]
The control positions for the main armament were located in the [[Top (sailing ship)|spotting tops]] at the head of the fore and [[mainmast]]s. Data from a {{convert|9|ft|m|adj=on|1}} [[Barr and Stroud]] [[coincidence rangefinder]] located at each control position, together with the target's speed and course information, was input into a [[Dumaresq]] mechanical computer and electrically transmitted to [[Vickers range clock]]s located in the transmitting station located beneath each position on the main deck. Wind speed and direction was called down to the transmitting station by either [[voicepipe]] or [[sound-powered telephone]]. The range clock integrated all the data and converted it into elevation and [[Deflection (ballistics)|deflection]] data for use by the guns. The target's data was also graphically recorded on a plotting table to assist the gunnery officer in predicting the movement of the target. The turrets, transmitting stations and control positions could be connected in almost any combination.<ref>[[#Brooks 95|Brooks (1995)]], pp. 40–41.</ref> As a backup, two turrets in each ship ('A' and 'Y' in ''St Vincent'') could take over if necessary.<ref>[[#Brooks 05|Brooks (2005)]], p. 61.</ref>

In 1910–1911, the four-inch guns on the roof of the forward turret of ''Vanguard'' were replaced by a {{convert|9|or|12|ft|m|adj=on|1}} rangefinder. This was removed about a year later, roughly at the same time when the rooftop guns were removed from the forward turrets of the other two ships.<ref name=b81>[[#Burt|Burt (1986)]], pp. 80–81.</ref> In late 1914, the remaining rooftop guns were replaced on the three [[sister ship]]s by 9-foot rangefinders protected by armoured hoods.<ref name="dread">Admiralty Weekly Order No. 455 of 6 October 1914, referenced in footnotes 16 and 17, {{cite web |title=St. Vincent Class Battleship (1908) |url=http://www.dreadnoughtproject.org/tfs/index.php/St._Vincent_Class_Battleship_(1908) |publisher=The Dreadnought Project|access-date=4 February 2017 |language=en}}</ref>

[[Fire-control system|Fire-control technology]] advanced quickly during the years between the ''St Vincent''s' commissioning and the start of World War I and the most important development was the [[Director (military)|director]] firing system. Mounted high in the ship, a fire-control director electrically provided data to the turrets via a pointer on a [[dial (measurement)|dial]], which the turret crewmen only had to follow. The director layer fired the guns simultaneously, which aided in spotting the shell splashes and minimised the effects of the [[ship motions|roll]] on the dispersion of the shells.<ref>[[#Brooks 05|Brooks (2005)]], p. 48.</ref> While the exact dates of installation are unknown, ''St Vincent'' was equipped with a director by December 1915 and the others by May 1916.<ref>[[#Brooks 96|Brooks (1996)]], p. 168.</ref> The ships were fitted with Mark I [[Frederic Charles Dreyer#Dreyer Fire Control Table|Dreyer Fire-control Tables]] in the transmission stations by early 1916, which combined the functions of the Dumaresq and the range clock.<ref>[[#Brooks 05|Brooks (2005)]], pp. 157–158, 175.</ref>