Earlier this year the IET Archives was very fortunate to receive a donation of the records of the Decca Navigator Company. This company owned and developed the Decca Navigator System, probably one of the UK’s major contributions to radio navigation since WW2, a radio navigation system that allowed ships and aircraft to determine their position by receiving radio signals from fixed navigational beacons.

Decca Navigator did not have its own formal archives, but a former senior employee of the company, who took a great interest in its history, had maintained close contacts with the Managing Directors of the company and collected the company’s records from these individuals over a period of time. This is therefore not a corporate archive as such but instead the records of a company collected by its senior managers. In addition to information about the history of the company and its formation, there are records related to the senior managers in the company, its finance and sales, technical articles and research, photographs, and perhaps the only complete set of the Decca Navigator house magazine in existence (1949-1981).

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The image above shows the cover of the first issue of Decca News, published in 1950, which became Decca Navigator News in 1951. The image shows Chief Officer of the S.S. British Merit, W R Mowbray, using a recently installed Decca Marine Radar, type 159.

The IET Archives is also very grateful to its volunteer, Eric Everatt, who has catalogued this collection which has been described at item level. Without Eric’s assistance it would not have been possible to catalogue this wonderful collection in such great detail.

History of the Decca Navigator Company

An engineer, William J O’Brien, had the idea of position fixing by means of phase comparison of continuous wave transmissions in the period 1936 to 1938. This wasn’t the first such system but O’Brien made some progress with it and undertook experiments in 1938 in California. Both the US Army and Navy considered O’Brien’s idea too complicated and the work ended in 1939.

O’Brien was a friend of Harvey J Schwarz, Chief Engineer of the Decca Record Company in England and he sent details of the system to Schwarz in 1939 to put to the British military. Robert Watson-Watt reviewed the system, but did not follow it up considering it too easily jammed. However, in October 1941 the British Admiralty Signal Establishment (ASE) became interested in the system, which was then classified as Admiralty Outfit QM, and marine trials were conducted in 1942. A copy of the letter from Decca Radio to the ASE regarding its interest in O’Brien’s navigation system, dated January 1943 is shown below.

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Further trials were undertaken in April 1943 and January 1944 by which time the competing Gee system was known to the Admiralty. The two systems were tested head-to-head under the code names QM and QH. QM was found to have the better sea-level range and accuracy, which led to its adoption.

21 minesweepers and other vessels were fitted with Admiralty Outfit QM and on 5 June 1944, 17 of these ships used it to accurately navigate across the English Channel and to sweep the minefields in the planned areas. The swept areas were marked with buoys in preparation for the Normandy Landings.

Decca Navigator Company Limited was formed in 1945 after the end of WWII as a subsidiary of Decca Records, and the system expanded rapidly, particularly in areas of British influence. Decca’s primary use was for ship navigation in coastal waters, offering better accuracy than the competing LORAN system. Post WWII fishing vessels were major users but it was also used on aircraft. Two of Decca’s test planes are show below (the first image is of a Vickers Valetta aircraft).

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At its peak Decca’s Navigator System was deployed in many of the world’s major shipping areas and more than 15,000 receiving sets were in use aboard ships in 1970.The system was employed extensively in the North Sea and was used by Helicopters operating to oil platforms.
Decca Navigator was acquired by Racal in 1980 which then merged Decca’s radar assets with its own. As the patents on the original Decca technology expired in the 1980s, Decca suffered at the hands of competitors, and its income declined. Decca was eventually replaced, along with LORAN and other similar systems by GPS during the 1990s. The Decca system in Europe was shut down in the spring of 2000, and the last worldwide, in Japan, in 2001.

The Decca Navigator Company collection has been catalogued with an archive reference NAEST 228 and is available to consult at the IET Archive Centre, Savoy Hill House, London.

Additional Comments Following Original Post

After this blog about the Decca Navigator Company was originally posted, Richard V Glenister kindly provided the two images below which show a Decca Plot trace taken during a search for a wreck and also a photograph of the plotter. The equipment was on the Salvage Vessel Droxford being used during a search for S. S. Boniface which had been sunk by a German submarine in World War I. Richard mentioned that the Decca model shown was a Decca Navigator Mk. 12 Multi Pulse with an associated Decca track plotter type 350. The radars used were a Decca Type 46 and Type 45.

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