Deflection Plotting

Deflection Plotting was a British concept for adjusting a torpedo director first proposed by Commander Alan M. Yeats-Brown. The "steady bearing" concept of Hallett's Director was a subcase.

A pamphlet was drawn up and issued in 1912, and a combination slide rule and plotting board invented by Lieutenant (G) W. M. James to facilitate its practice, permitted the required deflection to be read off rather than calculated as detailed in the pamphlet.

Tests were also underway in 1912 to use the calculator with a system designed by Lieutenant (T) B. E. Reinold to permit a rangefinder, gyrocompass receiver and Forbes speed indicator to automate the process further.

It is not clear to me whether the Torpedo Control Plotting Instrument and/or the Dreyer Torpedo Control Table were deemed to be instances of this method.

Abolished

By mid 1919, a meeting of the Fleet Torpedo Committee decreed that "deflection plotters" should be abolished, as their results, if accurate, were stale. The momentum in torpedo attack from the battleline was progressing toward attack against the entire enemy battleline, based upon its direction of advance. It is not plainly apparent which systems were to be encompassed in this decision, especially the T.C.P.s and the Dreyer tables.

See Also

• Hallett's Director
• James Calculator
• Torpedo Control Plotting Instrument
• Dreyer Torpedo Control Table

Bibliography

• H.M.S. Vernon. Annual Report of the Torpedo School, 1912, with Appendix (Wireless Telegraphy). Copy 17 at The National Archives. ADM 189/32.
• H.M.S. Vernon. (Feb 1914) Annual Report of the Torpedo School, 1913, with Appendix (Wireless Telegraphy). Copy 42 at The National Archives. ADM 189/33.
• H.M.S. Vernon. Annual Report of the Torpedo School, 1918. C.B. 1527. Copy 143 at The National Archives. ADM 189/38.