A Rate Officer is a Royal Navy fire control duty used in larger ships, almost always reserved for an officer in an aloft position such as a spotting top.
His primary task is to be personally responsible for selecting the range rate to be used in firing.
Station and Equipment
The point in having such a role was to ensure that the rate would be selected by a man who could personally have a chance to see how well it reflected the geometry of the battle. To this end, his station was aloft.
He would have a Dumaresq in hand to help him compare the apparent heading and speed of the enemy to the range rate in use and any suggestions for new values that might be communicated to him by Navyphone or Voicepipe. In light cruisers, there might also have a Vickers Range Clock near at hand, but a junior number would be in charge of applying the rates commanded by the rate officer, as well as any spotting corrections provided by others. In larger ships, the clocks and plotting would be conducted in the T.S.
- Admiralty, Gunnery Branch (1913). Gunnery Drill Book for His Majesty's Fleet. (Book I.) (Instructions for Power-Worked Mountings). London: Eyre and Spottiswoode, Ltd..
- Admiralty, Gunnery Branch (1917). The Director Firing Handbook. O.U. 6125 (late C.B. 1259). Copy No. 322 at The National Archives. ADM 186/227.
- Admiralty, Gunnery Branch (1918). Director Firing For Flotilla Leaders and Destroyers. Pub. No. B.R. 934 (late O.U. 6127 and C.B. 1461 and 1461(A). The National Archives. ADM 186/234.