Standard Bearing Plot
The Standard Bearing Plot was a well-conceived but tardy replacement for the original bearing plot used on Dreyer Fire Control Tables through Jutland. It's design goals appear to be a more compact dimension, better use of the paper for visual estimation of bearing rate, and enhanced integration with the Dreyer table as well as the outboard users of the table's gun deflection output.
Though the standard bearing plot is well documented in the Handbook for Capt. F.C. Dreyer's Fire Control Tables, 1918, this is actually quite misleading, as the devices never saw service to the extent implied. It is possible that the only ship using a standard bearing plot on its Dreyer table was Ramillies from July, 1917.
The standard bearing plot featured
- a bearing vs. time plot with Bearing Rate Grid
- a pair of deflection drums
- a dial indicating the current bearing, uncorrected for yaw
- a Deflection Totaliser to permit summation of corrections and their transmission from the Dreyer table
Inputs and Outputs
|Inputs to Standard Bearing Plot|
|Input||Source of Data||Means of Expression|
|Own Ship's heading||Gyro-compass||continuously, by motor|
|Relative target bearing||Optical instrument aloft||continuously, by motor|
|Bearing 'cut' indication||Button near target bearing indicator device||momentarily, by electrical pulse|
|Gun range||from Dreyer table's Spotting Corrector||continuously, by shafting|
|Bearing rate||bearing plot operator's use of rate grid||by local bearing rate handle|
|Dumaresq deflection||lining up with commanded deflection on dumaresq deflection drum||by local bearing rate handle|
|Dumaresq Deflection (corrected for range)||from local gun deflection drum||by a handle on face of deflection totaliser|
|Deflection corrections||spotters, Wind Dumaresq operator||by handles on face of deflection totaliser|
|Outputs from Standard Bearing Plot|
|Output||Destination||Means of Expression|
|Gun Deflection||T.S.'s Deflection Master Transmitter||occasionally, by manual working of totaliser's chasing output handle|
|Dumaresq Deflection||for cross-checking with dumaresq||read from dumaresq deflection drum|
- Brooks, John. Dreadnought Gunnery and the Battle of Jutland, p. 174.
- Brooks, John (2005). Dreadnought Gunnery and the Battle of Jutland: The Question of Fire Control. Oxon: Routledge. ISBN 0714657026. (on Amazon.com and Amazon.co.uk).
- Admiralty, Gunnery Branch (1918). Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. C.B. 1456. Copy No. 10 at Admiralty Library, Portsmouth, United Kingdom.