Range Master Transmitter

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A Range Master Transmitter was an instrument mounted on the bulkhead of the Transmitting Station in a Royal Navy vessel. Alterations in range arrived from the Spotting Corrector of a Dreyer Fire Control Table by a flexible shaft. An operator would then note the change and Follow-the-Pointer to relay the data on to the guns and director.

It was mechanically linked through Cross-connecting Gear to drive a series of Range Transmitters so the one effort would inform all the turrets and directors who needed the data.


The actual outputs of the Dreyer Fire Control Tables were flexible shafts coming from handles worked at the table. In the case of range, this came from the spotting corrector. In order to avoid imposing undue load on the flexible shaft, it was seen as wise to place another F.T.P. dislocation in the data path, and the range master transmitter provided this buffer. The range indications from the Dreyer would move a red pointer on the clock face of this instrument, and the operator would chase it with a handle driving a black pointer. This action would also drive a series of range transmitters, one for each turret (and one for each director) to pass the data on by a step-by-step circuitry.

Each transmitter had a knob by which a bias could be introduced in that transmission path only. It is not clear if this capability was permit a willful increase in salvo pattern for range or for some other purpose.

Those used with Mark IV* tables, and possibly others, had a maximum range of 20,200 yards and had cams for full charge, reduced charge and sub-calibre firing, altering the equal spacing around the master transmitter dial to unequal spacing.[1]

The range was probably altered 200 yards by each full revolution of the handle.[2]

See Also


  1. Captain F. C. Dreyer's Fire Control Apparatus, Mark IV, Sheet 18.
  2. Manual of Gunnery (Volume III) for His Majesty's Fleet, 1915. p. 36.


  • Elliott Brothers, London (1916). Captain F. C. Dreyer's Fire Control Apparatus, Mark IV. Copy 19 "as fitted in H.M.S. Royal Oak" at H.M.S. Excellent Library, Portsmouth, United Kingdom.
  • Schleihauf, Bill (2001). "The Dumaresq and the Dreyer, Part I-III." Warship International 38 (1-3).
  • 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.