The following table illustrates the growth of the Decca chains world wide. By 1976, Decca had grown to more than 50 chains.  Eventually the popularity of GPS started to erode the base of  Decca Navigator users. By 1996, there were only 30 chains left. If anyone can provide missing data, please contact Jerry Proc E-mail: jerry.proc (at)

Some stations had a name board at the front gate, while others had no markings apart from the normal danger and keep out signs. Chains were identified predominantly by their service area. Individual sites were normally referred to by the nearest large town. Almost all sites were located in the middle of nowhere so an exact reference was difficult except for latitude and longitude. Actual site names may be very hard to find on any generally available maps. To simplify matters, all stations in Northeast Europe are shown in accordance with the List of Interference Sources in the NELS coverage prediction tables. Since the datum from which decimal co-ordinates is drawn from is unknown, the figures shown should be assumed to be approximate.

The group that was responsible for the placement of the chains was the Systems Planning Group of the Decca Navigator Co. They were based in a small, separate office building and used all kinds of maps and geophysical data to plot predicted coverage and accuracy. They prepared outline charts, calculated the station goniometer settings and used the results of chain monitoring exercises to make adjustments to the pattern prior to operational use. They also published error correction data for the chains which could be applied based on the time of day to achieve maximum user accuracy.

 I.D. & NAME
Australia  07/1972
8E - Dampier
4A - Port Hedland
Bahamas  <1964 Early 70's? ?  
Bangladesh Late 1950's  >1985 6C - Bangladesh  
Canada  1957 
Aug 19,1957
9C - Quebec
9C - Anticosti
6B  - West Newfoundland
6B - Cabot Straits 
2C - East Newfoundland
7C - Nova Scotia 
Denmark Oct. 1948  31/12/1999 7B - Danish Chain  
England July 1946
June 1951
July 29, 1952
5B - English
3B - North British
2A - Northumbrian
1B - South West British
Finland 1971 31/12/1999 6E - Gulf of Finland
France  Oct 1953
8B - French
??  - Southern French
Germany Jan 17, 1952 03/1992 3F - German 
India  1962
Feb 15, 1979
7B - Bombay
8B - Calcutta
2F - Salaya
Indonesia  1975 -- Proposed but not built.   
Iran (North Persian chain)  1960 01/05/1980  5C - North Persian Gulf chain
Ireland  05/31/1973 05/2000 7D - Irish  
Italy  1959
?? - NATO evaluation chain
?? - Sicily evaluation chain
Japan  07/1967
9C - Hokkaido
2C - Hokuriku
8C - Kanto
7C - Kita Kyushu
4C - Shikoku
6C - Tohoku
Netherlands 1968
June 30/1972
9B - Frisian Islands
2E - Holland
Nigeria  1976 1982 or 83
1982 or 83
8F - Lagos
3A - Mid Western
7F - Rivers 
2B - South Eastern
Norway  May 27/1967


See Norway
text for
7E - Finnmark
9E - Helgeland 
3E - Lofoten 
4E - Trondelag
0E - Vestlandet
7, 9
Scotland  1975
Jun 26,1956
8E - Hebridean
6C- North Scottish
South Pacific (unconfirmed) ? ? Chain ID ? .  See map here 11
South Africa 08/1973
6A - Cape
8A - Eastern Province
4A -  Namaqua
10C - Natal
9C - South West Africa
Spain  01/1969
January 1995
January 1995
4C - North West Spanish
6A - South Spanish
Strait of Hormuz 1978 -- Proposed but not built.
Sweden  06/1962
14 Aug 1970
June 2,1967
5F - North Bothnian
8C - South Bothnian 
4B - North Baltic
0A - South Baltic
10B - Skaggerak
United Arab Emirates ( South Persian)  1961 1999  1C - South Persian Gulf chain
United States of America 1958
Prior to 1985
5C - New York City
??  -  California
Vietnam 1962/63 ?
??    - South Chain
??    - Central Chain


YEAR can mean the date that the contract was signed to build the chain or the date when the chain came into actual use or the date they were formally accepted. These dates have been researched to be as accurate as possible in spite of not having any official documents for reference. Where possible, I have tried to explain it in the text.

1. Only two were built - Lagos and Rivers.

2. Item 2 deleted.

3. This chain had very short service life. Does anyone know the exact reason?

4. This was a two slave chain as of June 1973 with the Purple Slave missing.  In the Mk 19 receiver, a switch allowed  the operator to disable the unused channel so the decometer would not produce bogus readings.

5. This was a two slave chain as of June 1973 with the Green Slave missing. In the Mk 19 receiver, a switch allowed the operator to disable the unused channel so the decometer would not produce bogus readings.

6. This chain radiated Mark 5 type transmissions only as of June 1973.

7. All of Norway's chains could not have been built in the same year. The date of 1968 came from Decca Navigator News without any other qualifier.

8. The date the contract was signed.

9. The ID for this chain was re-assigned at some point in the chain's service life. Please refer to the individual chain for details.These updates are provided by John Beattie the former Corporate Marketing Manager for Marine Policy for Racal-Decca Marine from 1982 to 1993 and then a consultant to them.

10. Dismantled August 1995.

11.The South Pacific chain is unconfirmed.


There are 11 groups of basic frequencies, numbered 0 to 10. In each of these 11 basic groups, 6 master frequencies, lettered A to F, are derived to provide for existing and future chains. Thus, in Group 0, normal master frequencies in kHz are:

0A - 84.100
0B - 84.105
0C - 84.110
This group is separated nominally by 90 Hz (in reality around 80 Hz) , Then the series starts:
0D - 84.190;
0E  - 84.195
0F  - 84.200.

The frequency interval between each numbered group is 180 Hz. ( ie [2A] 84.4550 - [1A]  84.2750 = 180 Hz difference). Group 10 includes only the A, B, and C frequencies. Please refer to the Decca frequency table  Figures 1 and 2 for more information.

Decca MARK 12 or MARK 21 receivers could be switched to each of these 63 frequencies. Earlier receivers could only be switched to the numbers only, where they will receive A, B, or C frequencies, but could not  receive the D, E, or F transmissions.

Because Decca Navigator only depended on the ground wave, it was possible to reuse chain ID's ( ie frequencies) around the world.  Chains sharing the same channel had to be at least 2,000 km apart. Any time a two slave chain was planned, Red and Green were used since that combination offered the best accuracy pattern under all conditions.



The Port Hedland 4A chain was established in May 1970 by the Australian Department of Shipping and Transport, a government agency responsible for the the maintenance of navigation aids along more than 12,000 miles of coastline at the time.
Turner River Master 84.820     kHz 20° 33' S  118° 29' E
Mundabullangana Station (shared) Red 113.0933 kHz 20 °25' S  118° 04' E
De Grey River Green 127.230   kHz 20° 21' S  118° 59' E

When the number of  iron ore carriers using the ports in northwest Australia increased, it was deemed necessary to install another Decca chain. As a result, the Dampier 8E chain was established to provide precision navigation for shipping in the Cape Dampier area off Western Australia for 300 miles of coastline. The Dampier chain also provided coverage for  Port Walcott (20.5833° S, 117.1833° E).
Woodbrook (inland from
Master 85.635   kHz 20° 53' S  117° 08' E
Mardie Station Red 114.180 kHz 20° 59' S  116° 21' E
Mundabullangana Station (shared) Green 128.453 kHz 20° 25' S  118° 04' E

Installed as Multipulse chains from the onset, both chains were collapsed around the 1987-1989 time period.


Australia had always taken a deep interest in the Navigator system and, as part of Decca's expansion campaign, sale personnel gave a number of presentations including a major symposium in Sydney organized by John Lucken.

The final  opportunity came in a rather roundabout way. In the 1960's, Japan's shipbuilding and motor car industries were expanding rapidly and as Japan has no natural source of iron and steel it was necessary to import large quantities of ore. Australia, although thousand of miles away, was the source selected. Japan had its own Decca Navigator coverage and many of the ore carrying vessels were already equipped with receivers. The ore carriers were large and the channels in Northern Australia were twisting and narrow. Decca was clearly a logical solution to the problem therefor two chains were built  - one in Dampier and the other in Port Hedland.

Dampier proved its worth to the large bulk iron ore carriers which navigated a narrow, twisting, 20 mile channel through off-lying shoals. Besides covering the .'confluence of shipping routes off Cape Dampier',  the chain provided accurate navigation in the approaches to Port Walcott, a new iron ore facility being developed in the area.

The decision to install Dampier was announced by the Hon. Peter Nixon, Australian Minister of Shipping and Transport, speaking at the first Australian Coastal Nav Aids Symposium held in Canberra in December 1971. To meet an urgent operational requirement, the Dampier Chain was built from scratch in seven months using 1880 type equipment and went into operation in July 1972. Norman J. Clarke (Nobby) from Decca's Chain Implementation Department oversaw the construction and commissioning of the two chains and then joined the Australian Department of Shipping and Transport. His family emigrated to join him there and they now live near Sydney.

Amalgamated Decca Surveys Pty Ltd also proposed chains for Wallal Downs, Derby and Gladstone but these were never built. The frequencies and coordinates shown above came from the Chain Basic Data (DN Systems
Planning Dept. New Malden) whereas the names came from the proposal.

Any breaks or disturbances of normal Decca transmissions were broadcast as "Decca Warnings" by the coast radio stations in the vicinity. These were Perth Radio (VIP), Carnarvon Radio (VIC), Broome Radio (VIO) and Darwin Radio (VID)

Additional info on  the Australian chains can be seen here.


This was known as the AUTEC chain and was built for the United States Navy  The acronym means Atlantic Undersea Test and Evaluation Center. It's still around today and based on Andros Island, Bahamas. AUTEC's purpose is to be the U.S. Department of Defense and Navy range of choice for conducting undersea warfare testing and measurements in the Atlantic. Decca was used to provide accurate position fixes to support the research which was being conducted on the AUTEC range.

Back then, the chain was run from the New York office of Decca Navigator Systems Inc (DNSI) but installed by the personnel from the UK.  DNSI was the company established in the USA to give Decca a presence in North America thus providing a single point  of contact for all the activities being pursued in the '60's and '70's.

This chain ran successfully as a Mk10 system with 820 control racks but had big problems with salt deposits on the insulators thus degrading performance. Decca tried all sorts of things like MS4 silicon grease but nothing really improved the situation until the rain washed off the salt. Eventually the stations were abandoned and the equipment was shipped to the UK for refurbishment and redeployment. . No information is available on the approximate opening or closing dates for this chain.

Bill Gaston of Marco Island, Florida and Christopher Rose, a former Decca employee have identified the locations of the former Decca stations. The Master was located on Pipe Cay in the Exumas. The Better Boating Association (BBA) Bahamas Chart Kit 4th Edition even has it noted on page 49. Another reference lists a Decca station on Great Exuma Island which is considerably south of Pipe Cay. Golding Cay, off the coast of Andros Island and Eluthera are the other two sites. Golding Cay is a rock in the ocean, not much bigger than a football field and situated at the entrance to South Bight, on the east side of Andros Island.
Pipe Cay (Central Exumas) Master   24 14' 46"N  76 31' 20"W
Great Exuma Island (2 km NW of Georgetown)  Red   23 32' 00"N  75 46' 20"W
Golding Cay (off  Andros Island) Green   23 13' 12"N  77 36' 10"W
Eluthera Island  Purple   24.9314N , 76.1900W 

Christopher Rose of  Orléans, France briefly describes the conditions. "Our accommodation was composed of portacamps - very makeshift. We were originally supplied by a yacht, then a converted coast guard cutter and finally once a month by a seaplane. The staff did three month shifts on the cays then had a two week break working at head office in Nassau. We were a  mixture of British and Americans I think, all ex-servicemen, but so was everybody in those days. Rotations were slow as people did not like being moved around too much. I once spent more than two years in one station in Vietnam. I heard a story from the Persian Gulf of somebody driving
his replacements off with his rifle."

Dan Ahart, a serious traveller, describes what he saw on Pipe Cay. "Our first stop was the abandoned U.S. Navy DECCA station on Pipe Cay. The station has been abandoned for about 20+ years, but it was once a communications station of some sort. I don't know what DECCA stands for, but knowing the military's penchant for acronyms, it probably has something to do with defense communications. The layout looked very familiar to me because I spent some time at similar stations when I served in the Air Force. It had the standard military generator building supplied by diesel fuel via an above ground pipe from a remote storage tank. Closer to the pier was the all purpose building, which included living quarters for at least five and maybe as many as nine personnel and an electronics equipment room. Adjacent, was the foundation of the antenna tower. Interestingly, the boiler for distillation of fresh water had not been removed".

Select this link to see photos of the Bahamas chain.


Bangladesh Chain 6C
Comilla ( near Chandpur) Master 85.185   kHz 23° 26' 60"N,  91° 12' 0"E 
Dohazari (near Chittagong) Red 113.580 kHz 22°  09 46 N,  92° 03 31 E
Khulna (near Jessore) Green  127.788 kHz 22° 34' 60"N,  90° 13' 0"E 
Mymensingh Purple 70.988   kHz 24° 44''34"N,  90° 23' 33"E


The Bangladesh chain was originally a Mk V survey built in what was then East Pakistan in the late 1950's for the hydrographical resurveying of the massive Ganges Delta after each monsoon. This was done with a fleet of boats using echo sounders during daylight hours. The huge changes of the river courses and sand banks after each monsoon made river transport difficult and severely hampered one of the main means of transportation in the country. This resurveying was used to expedite re-use of the waterways after each monsoon.

The war of Independence in the early 1970's seventies led to the formation of the new country of Bangladesh, and during the war, the Decca chain went off the air. After cessation of hostilities, it was refurbished as a Mk10 chain as part of British Government aid programme. One of the stations, Red, near Chittagong, had been destroyed in the fighting, so the opportunity was taken to re-build on a new site about 20 miles south at Dohazari. All the other stations used the existing buildings.

At the time of re-building there were tremendous difficulties. The Red station was reputed to have been built with the first cement to come into Chittagong after the war. Malnourished children were everywhere and smallpox was endemic. Smallpox was actually finally eradicated from Asia by the World Health Organization while the chain was being built. Chandpur, close to the Master station, had one of the last of the world's smallpox outbreaks. Decca engineers did not have enough fuel to boil the drinking water, but luckily potable water came from a deep tube well and was reputed to be good.

While one Decca engineer was alone at the Red station, a battalion of the Bangladesh Rifles came into the compound to take the station over as a billet. When he walked out from the inspection bungalow to greet them, they hastily backtracked out of the gate - probably surprised to see a European in such a remote location.

The Dohazari Red slave was at the end of the railway line south from Chittagong. When the Decca station was being built, there was no timetable posted. Decca arranged for a runner to be posted on the station platform. Whenever a train arrived, he would run into the Decca compound to announce its arrival.

During the stability survey, Decca used the Government inspection bungalow at Jessore as a monitoring point, because it had a trig point (coordinates) at the corner and its position was therefore known. The monitoring station was set up in a bedroom, but they were hastily removed when the President came to town and slept in the room.

The monitoring station antenna was finally installed on the roof of a civil servant's house in Dhaka, the capital, and the whole chain was run by  the Bangladesh Inland Waterways Transport Authority (BIWTA). All stations ran on local generators and had masts of 150 feet using T-array aerials. Transmitters and phase racks were thermionic, even after the re-furbishment. Being so close to the equator, the skywave effect was enormous. Starting around 16:00 hours, accuracy degraded rapidly. The chain was reopened by Judith Hart, Minister of Overseas Aid in the British Labour government, in 1975. This chain had the distinction of being one of the few (or the only) chain used for inland water navigation. The chain was still in use in 1985. (Does anyone know the exact date that it closed?)

The name of the capital "Dhaka" caused endless confusion when Decca employees tried to explain who they worked for.

A map of the Bangladesh chain and photos can be viewed here.


The contract to build Canada's four Decca chains was signed in 1957 and by 1958, it is confirmed that one of the  chains was in full operation and in use by The Royal Canadian Navy. The other chains became operational shortly thereafter and entered a lengthy acceptance period .

John Adams of  the Canadian Coast Guard provides this summary of the Decca Navigator chains, "Following several years of testing, the first official Decca navigation service in Canada was established in 1961. The service consisted of four Decca chains". It is believed that 1961 is the official acceptance year for all the chains.  The Canadian licencee for Decca navigator was Computing Devices of Canada, Ottawa Ontario".

In 1952, the Canadian agent for Decca was S. Stephenson, P.O. Drawer 99, 1175 Bay St., Toronto. Telphone:  Midway 7363.

 Cabot Strait Chain 6B
Grindstone, Iles de La Madeline
Islands, Quebec 
Master 85.180     kHz  47.350ºN, 61.933º W
Channel Port-aux-Basques, NF  Red 113.5733 kHz  45.633ºN, 59.233º W
Antigonish, N.S. Green 127.7700 kHz  45.733ºN, 61.900º W

There was no Purple slave for this chain. This service was discontinued in October 1982.

 Nova Scotia 7C
Chester, Nova Scotia Master 85.3700 kHz 44.533ºN,  64.233ºW
Alma, New Brunswick  Red 113.827 kHz 45.560º N, 64.933º W 
Jordan Bay, Nova Scotia Green 128.055 kHz 43.700º N, 65.233º W 
Ecum Secum, Nova Scotia Purple 71.142   kHz 44.967º N, 62.150º W 

7C was the first Canadian chain. Service was discontinued in March 1982

In the Nova Scotia chain,  the transmitters were manned 24 hours per day. To ensure operational readiness, the transmitters were "rotated" at both the master and slave sites in sequence. Starting at 12:00 noon, the operational transmitter at the Master station was dropped and it became the spare. The one that was the standby unit now became operational. The one that was previously the spare became the standby unit. At 10 minute intervals, the same sequence followed at the Red , Green and Purple slave sites. On subsequent days, the the sequence continued to ensure that all three transmitter "modules" were on-line at regular intervals. Of course if a transmitter was down for some serious maintenance, the round-robin sequence would have been shared among two transmitters only. Rotating the transmitters at noon was done for a reason. It was deemed that the "atmospherics" were most stable at this time of the day in the VLF band and doing it then would minimize any potential disruptions to the users of the system.

Anticosti Chain 9C
Port Menier, Anticosti Island, Quebec  Master 85.725   kHz  64.450º W,  49.850º N
Shippegan Island, New Brunswick  Red 117.157 kHz 64.683º W,  47.850º N
Natashquan, Quebec  Green 128.587 kHz  61.817º W,  50.183º N
Sept Iles, Quebec. Purple 71.437   kHz 66.617º W,  50.150º N

John Molloy-Vickers provides a background note for this chain. "There was an evaluation chain (9C) covering Montreal to Quebec City and it was installed in November 1957 by Decca Navigator and  CDC. It was Mk10 chain with 820 control racks intended for airborne use on the terminal approaches to Montreal's Dorval airport. The 1958 Montreal ICAO meeting killed it and it the chain was moved to become the Anticosti Chain 9C".

This service was discontinued in March 1984.

East Newfoundland Chain 2C
Port Blandford, Newfoundland Master 84.4650    kHz 48.350º  N, 54.167ºW 
Pouch Cove, Newfoundland Red 112.6200  kHz 47.7667ºN, 52.7667º W
St Lawrence, Newfoundland Green 126.6975  kHz  46.917º N,  55.383ºW 
Comfort Cove, Newfoundland Purple 70.3875    kHz  49.350ºN 54.867º W, 

This service was discontinued in December 1986.


The St Lawrence Seaway was the starting point for Decca's  expansion into North America and four chains were built for the Canadian Government. These chains provided excellent coverage and were widely used for fishing operations. It was an early and important development for the company..

According to an article in Decca Navigator News (Sept 1976), Decca Radar Canada Limited and The Decca Navigator Company (Canada) Limited were set up in 1953. An extensive sales and service organization to meet the demand, particularly for radar was established with headquarters in Toronto and was followed by a steady expansion.

In 1957 the manufacture, rental and servicing of shipboard Decca Navigator receivers passed to Computing Devices of Canada under a prior North American licensing arrangement. With the transfer of some Decca personnel from Decca Canada and the UK, Computing Devices Company (CDC) formed a marine electronics sales and service organization in the Atlantic Provinces and at the same time were also appointed representatives for Decca Radar equipment for this area of Canada. Concurrent with these developments, Decca Navigator chains of transmitting stations were erected in Eastern Canada, and as a result of proving trials, four Decca Chains were purchased by the Federal Ministry of Transport to provide better facilities for increased shipping expected with the opening of the St Lawrence Seaway in 1959 and to assist the development of the Eastern Seaboard fisheries. The Canadian fishermen in particular rapidly equipped their vessels and CDC commenced manufacturing receivers.

At the same time, a heavy investment was made by CDC in providing service stations even in remote parts of Newfoundland and Nova Scotia.. Computing Devices added to their marine product range and operated under the divisional title of ComDev Marine. By 1976, some 500 local fishing vessels were equipped with Mk 12 or Mk 21 receivers.

Decca Radar (Canada) Ltd, since its establishment, had achieved great success in meeting the demand in Canada. In addition to a wide range of shipborne radars - no less than 28 new Decca equipment types were introduced for the '70s - the Company had been active in developing and supplying advanced equipment for Vessel Traffic Management facilities and for engine room control and monitoring systems.

When the Canadian chains closed for good it was noted that the Nova Scotia chain was only one transmitting the old 'V' format yet the other three chains had been upgraded to Multipulse. By the end, certain tubes had became very scarce and the only source for new tubes by the early 1980's was in Czechoslovakia.

Select this link to see a map of the Canadian chains.


Samsø Island, Denmark Master 85.365   kHz 55.950° N, 10.583° E
Møn Island, Denmark  Red 113.820 kHz 54.950° N, 12.467° E
Højer, Denmark  Green 128.048 kHz 55.017° N, 08.717° E
Hjørring, Denmark  Purple 71.138   kHz 57.450° N, 10.050° E


Denmark was The Decca Navigator Company's first overseas chain. After the English chain 5B was built, it was realized that more receiver rentals would be required in order for the new company to prosper and profit. With this in mind, the Danish chain was built and operated by Decca with a subsidiary company in Copenhagen. Immediately the overall Decca coverage was roughly doubled. So too were many of the operating expenses. Although the number of rentals did not double, the significance of the overseas development was considerable, laying the groundwork  for expansion in the rest of Europe.

Around 1990, the Danish Government purchased the Danish Chain 7B from the Decca Navigator Company Ltd  for a low price. Later, after arbitration between Racal and the Danish Government, a Danish court increased the amount of compensation. After the purchase, the Danish Government levied User Charges on their fishermen who used Chain 7B.

Select this link to see the Danish chain.
Photos of the Møn Island station (off-site link) can be viewed here.


Puckeridge, England  Master 85.000   kHz 51.817° N,  00.083° E
Norwich (aka Shotisham), England Red 113.333 kHz 52.550° N,  01.333° E
Lewes, Sussex (aka East Hoathley), England  Green 127.500 kHz 50.917° N,  00.150° E
Warwick (aka Wormleighton), England Purple 70.833   kHz 52.200° N,  01.367° W


The first chain of Decca Navigator stations was established in southeast England in 1946. All stations had unbroken transmissions, 24 hours per day.

With its short base lines and high radiated power, it performed well and despite its lack of Lane Identification, it  provided excellent service to the early users. It was the English chain which established the reputation of Decca for both accuracy and reliability. Furthermore, it was this chain that provided the "test bed" for the development of Decca and was the centre for much of the promotion of the system.

It was in these early days that the foundations of the receiver rental/maintenance system were laid. An effective organization was set up in the UK and, as time went on, this organization spread world-wide. The effectiveness of this network was a great contributor to the spread of the System overseas. In the promotion of every overseas chain, there were air and/or marine demonstrations of the system using the English chain. As a sales "tool", the chain was invaluable.

Overall maximum dimensions of a typical transmitter site were 1100 feet by 700 feet but the actual ground area occupied by the station was slightly less than that (750 ft. by 150 feet.) The buildings for the transmitters were simple, single storey, prefabricated units set on a concrete foundation.

The mast and aerial system on the Decca Navigator Ground Station was of special design and had an unusually high degree of efficiency at the low frequencies employed. Field strength measurements showed that the radiation efficiency was some 45%. Transmitter output, being at 2 kilowatts, meant that 900 watts could be expected as radiated power. This power level was deemed sufficient to overcome unfavourable reception conditions.


COVERAGE: This map of the UK illustrates the coverage of the English Chain. With respect to the master station located just north of London, the solid circle indicates 300 miles distance while the dashed circle is 350 miles. That was roughly the range deemed for reliable reception of Decca signals during daytime. The British Admiralty designated a range of 240 miles from London as being the furthest reliable distance. From this map, dated 28/8/46, it is very evident why Decca was only useful as a coastal navigation aid.

After it was found the English chain could not cover the whole of the UK 24 hours per day because of skywaves ruining lane identification,  the transmitter power was stepped down and for the last 25 years of operation, the effective radiated power was only in the area of 40 to 100 watts.

Donald W. Rayner Sr. worked at the Red slave of the English chain in Norwich between 1946 and 1948. He recalls this period with great clarity.  "Notice on Petty Officer's bulletin board at RN signal school, Leydene, Hants in Jan, 1946 -  Seeking to hire W/T ratings being released from post war service. Applicants to contact Decca Navigator in London.

I, and one Norman Thomas, a ‘Geordie’ Both applied and later were assigned to a site located on the ‘Kidner’ farm, Poringland/Shotesham All Saints near Norwich, Norfolk. We were met by a John Mears who became station manager and a contact man from DECCA in London. With this minimum staff, and a local contractor, construction started. Throughout the ensuing months the station took shape. It would be close to the end of 1946 before we got to transmitting.

During this time we had a visit from one, H. Toller Bond who was identified as being the head of design and engineering. On one visit he brought a gentleman identified as a ‘Mr. O’Brien’ the American inventor of the system. He was a US amateur radio enthusiast who had presented his ideas to the US military during the war and was turned down. Being a friend of a Mr. Schwartz who was president of British DECCA Records in London, he went over and sought his help.

The Royal Naval Signal school where Toller  Bond  was on staff became involved in design of the system. I believe the RAF may also have been involved since I met several company officers who had been ex-RAF.  Preliminary testing of a temporary ‘chain’ occurred during the Normandy landings, pinpointing areas for close support for troops on the ground but I have no direct knowledge of this activity. When operations started, we hired additional staff. Seven in, all with Mears, being Station Manager. I got tagged as Assistant Station Manager We were assigned a small new ‘Fordson' van for transport. Our shift hours were "different" . A night shift was defined  from 6PM to 8AM with 2 days off afterwards. Since the manager had a penchant to be absent for days, hence my unpaid promotion to Assistant Manager.

Equipment breakdowns were frequent as were trips to London repair shop. The special receivers were housed in a separate small building that was completely encased in fine wire mesh and grounded with the antenna mounted on its roof. Output cables were under concrete to the main transmitter building. Two large diesel generators were housed in a separate building with one running at all times due to power outages occurring frequently. We had an underground diesel fuel tank and a gasoline tank used for the starter motors mounted on the diesel generators.

Domestic notes: We were all housed in private homes locally but these were mostly farm cottages for farm workers. We asked for housing. Decca sent the company Sec. Treasurer to discuss our needs. Nothing happened.  This action eventually prompted me and my wife to leave and emigrate to the United States for better job opportunities.

In 1993 I visited this old site. The main 138 foot tower was gone replaced by a smaller antenna system.Other changes included the elimination of the diesel generators..  The staff consisted of one operator and a small house for him and wife. With the station due to close, both were planning to return to India, their homeland. On a personal note,  I was never an engineer....just a happy go lucky ham interested in electronics. Those large high power, low frequency transmitters with their glowing rectifiers fascinated me.

I was 25 then. Now I am 82 (2003) and living in this seniors village nestled in the foothills of the Allegheny mountains in Pennsylvania.  I’ve seen  it all and done it all in ham radio. It's been a blast".

Kidsdale, Scotland Master 84.645   kHz 54.700° N, 04.417° W
Clanrolla, N. Ireland  Red 112.860 kHz 54.500° N, 06.333° W 
Neston, South Wirral, England  Green 126.968 kHz 53.267° N, 03.050° W
Stirling, Scotland  Purple 70.538   kHz 56.067° N, 04.067° W 

Coverage of the Irish Sea.  Stirling was also the Red slave for the Northumbrian chain.
Photos of the North British Chain can be viewed here.

Allerdean Greens, England
(a.k.a. Berwick)
Master 84.455   kHz 55.700° N, 02.033° W
Stirling, Scotland  Red 112.607 kHz 56.067° N, 04.067° W
Peterhead, Scotland  Green 126.683 kHz 57.517° N, 01.850° W
Burton Fleming, Yorkshire, England Purple 70.379   kHz 54.133° N, 00.317° W


This chain was established to cover a gap in the North Sea and the Firth of Forth. Along with the Hebridean chain, it used re-furbished  820 series, thermionic valve equipment bought back from the USA. The USA had two experimental chains - one in California used for airborne trials, and one around the Bahamas reputed to have been used for submarine navigation. It is not certain which chain ended up where.

The Northumbrian chain had two shared stations -  Stirling and Peterhead. This meant that the masters at Kidsdale and Orkney had to be synchronized. In the end five chains were synchronized to allow slave sharing.

Decca trivia  - What was the population of Allerdean Greens at the time? Answer - Pop = 6. It was a minor hamlet south of Berwick

Photos of the Northumbrian chain can be found here.

Bolberry Down, Devon, England  Master 84.280   kHz 50.233° N, 3.833° W
St..Helier, Jersey, Channel Islands Red 112.373 kHz 49.250° N, 2.083° W
St.Mary's, Isles of Scilly, England  Green 126.420 kHz 49.933° N, 6.300° W
Llancarfan, Wales  Purple 70.233   kHz 51.433° N, 3.383° W

Chain 1B was officially opened on July 1952 on the Motor/Vessel Vecta. The chain provided coverage for the south and south east coasts of Ireland, Cornwall and the Scilly Isles.

Northern limit 51° 25'N
Southern limit 52° 14'N
Eastern limit 4°  5'W
Western limit 6°  5'W


David Jones provides some closing notes  for Decca, UK. "The final development phase of the UK Decca chains took place in the late 1980's when many sites were updated with a final version of the station equipment. This was a fully automatic and very compact design which permitted all the equipment to be housed in a small shelter. This program was carried out for the UK Government department that operated the chains. After this, many of the original design and support staff were let go. Racal then sold off the  Navigator and Marine radar business as part of it's overall break-up of the group. Litton Systems brought most of these entities including the Austin Insulator Company. Later, they decided to sell off Austin Insulators since they could not accept the potential liability of having a block of ceramic hold up a massive steel tower even though none had failed up to that point. Austin was purchased by a former Decca Navigator chain manager, Pat Warr.

According to John Molloy-Vickers, "In the early days of the UK chains., we installed a morse key and a Marconi receivers at all the UK station sites. The idea was that a navy man would turn up at the station and start keying the Decca transmitters in the prescribed code which would warn the British nuclear submarines to standby and deliver in the event that the Cold War turned hot. !"

Richard Caddy was the last Decca employee and was the person who shut off the lights. He provides some follow-on information after the Decca system ceased broadcasting. "When at all came to an end, we dumped almost everything but Walter Blanchard and his amateur radio team had some good pickings. However, I arranged for the complete master station from Puckeridge to be shipped to the Trinity House Museum at Great Yarmouth, along with the single tuned mobile coil house. Jointly, that comprises a  complete station. The ex-Berwick master station was shipped to the Northern Lighthouse Museum together with the double tuned mobile coil house. At this time, (Sept 2003) we have two complete Decca stations in mothballs and either could be fired up into a dummy aerial at any time.

When I  last spoke to Peter Reilly at Galway in December, 2000 the Irish Government had done nothing about decommissioning their old stations although transmissions were switched off in mid May 2000. The Company also held a good quantity of equipment which went on display in March 2000 at a conference at Church House, Westminster. There is also a  good exhibition of Decca equipment aboard HMS Belfast at Tower Bridge so all in all  the hardware side of the system is fairly well catered for.

The East Hoathly mast was sold to NTL who chopped 75 foot off the top and used it as a phone mast. In Scotland, the Butt of Lewis and Shetland sites went to the UK Coastguard. The Stirling site was taken over by NLB and the  Wormleighton site by Trinity House for transmission of Differential GPS inland. I believe that many of the other sites were demolished".

Select this link to see a map of the UK chains, photos of a modernized Decca station and other stories relating to Decca in the UK.


Gulf of Finland 6E
Mäntsälä, Finland Master 85.2700 kHz 60°30’59.16”N   25°10’42.12”E
Padva, Finland  Red 113.693 kHz 60°00’27.91”N   22°49’30.4”E
Sydänkylä, Finland  Green 127.905 kHz 60°30’37.65”N   27°26’18.23”E
  Orange 116.53566 kHz  

The Gulf of Finland chain was built in 1969-70, and became operational in 1971.
NAVIDEC was the Decca agent in Finland and was known as "THE DECCA HOUSE" .

A map of the 6E chain can be viewed here.


After WWII, the Société Française Radio-électrique (SFR) sent a mission to the UK in order to find out if any radio devices developed during the war could be be put to use in any peacetime applications. The mission was fortunate in arriving in London on the very day when the secrecy ban on wartime DECCA Navigator was lifted.

The SFR saw that this new system showed great promise in both marine and aeronautical applications. On December 1, 1945 the SFR signed a first agreement with the Decca Navigator Company. On April 8, 1948 , this provisional agreement was replaced by a contract which granted SFR a license to manufacturer and exploit Decca Navigator in the French Union.
Another company of the C.S.F. Group, the Compagnie Radio-Marine was entrusted with the application of the system to the French merchant marine.

On October 6, 1951, after numerous air navigation tests, the Secretary General of Civil and Commercial Aviation decided to install a transmitter chain in France. This chain, constructed by SFR, was opened on October 24, 1953 by M. Paul Devinat, Secretary of State for Public Works and Civil Aviation. The French Navy  saw the possibility of using Decca Navigator for hydrographic survey and mine sweeping. Hence, semi-mobile chains were developed and built for that purpose.

Chain 8B  - French chains were established primarily to support night air mail flights by the French Post Office.
Montluçon Master 85.5450   kHz 46° 19'N, 2°36'E
Amboise Red 114.0600 kHz 47° 25'N, 0°58'E
Saint-Germain-Du-Plain Green 116.9115 kHz 46° 42'N, 4° 58'E
Aurillac Purple 71.2875   kHz 44° 55'N, 2° 27'E

The St. Germain station was 13 kms east of Chalon Sur Saone. Sometime between 1957 and 1973, the Green had been shut down as being since it was of no real use for marine coverage in the Bay of Biscay.

John Molloy-Vickers who worked on the Green slave recalls his experiences in France. "In 1958, we  converted the main chain to Mk 10 from Mk V. I worked on Green at Chalon sur Saone during the conversion and then touring the chain for some months doing troubleshooting.  Since I was the only Decca man left there, I had to improve my French in a hurry. I was always being stopped by the Garde Mobile and being searched as there were constant problems with Algerian terrorists and bomb attacks.. The chain was run by the French Ministry of Aviation. It was not the most efficient of organizations in those days. If a fuse blew or a valve went defective, permission had to be obtained from the Chef de Station to do something about it! There were two- one technical and the other for office work  It was a classic case of a civil service at its worst although I will say everybody was always very pleasant and it was all very educational. However, we kept the chain going  and we had reasonable results from aviation users and the Paris Air Show. There was no real marine interest at that time".

The French Main chain was originally operated by the French but operation was taken over by Decca OPD  in 1965  for Eurocontrol trials Under the French, the chain was used for general navigation purposes.

For more information on Decca France, select this link.

Brilon,  Germany Master 84.7400   kHz 51°27'N,   8°43'E
Coburg, Germany Red 112.9867 kHz 50°20'N,  10° 59'E
Zeven, Germany Green 127.1100 kHz 53° 17'N    9°16'E
Stadtkyll, Germany Purple 70.6167   kHz 50° 22'N  6° 32'E


The original German chain was set up to assist with the Berlin air-lift and the support of forces in the region and was assigned a chain ID of 9B. An ex-Decca sales manager who was in an RAF navigator during this period said that the worst cargo was coal. The sacks had to be manhandled in and out of the aircraft thus leaving everything and everybody covered in black, dusty  powder. After the initial crisis was over, the chain was probably left in place to support the RAF aircraft in West Germany who already had an  installed base of Decca receivers.

By December 1951, a new German chain had been built and was officially opened on January 17, 1952 at the offices of the Telefunken Company in Dusseldorf. Assigned as chain 3F, it opened for business using 2.5 kw transmitters and antenna masts that were 100 meters high. Later on , the chain was upgraded to Multipulse. The chain frequencies shown in the table are those for 3F.

One of the stations was  located in the pretty village of Stadtkyll, south west of Cologne, in the Eiffel region of Germany. David Jones remembers the station when he was there in January 1977. "The German caretaker at the station was a tank driver in WW2 and would speak with pride about the smooth ride inside his Panzer tank as it went through a house". It is believed that the Zeven station was also the Green slave for the German chain 3F.

An interesting note was spotted in a Decca technical publication dated 1973." WARNING - Although the
Frisian Islands chain is using the same frequency as the old German chain, namely 9B, the ground stations are not in the same positions and therefore the old German charts cannot be used with the Frisian Islands chain.  See notice to Mariners 1977(p) of 1967 ". John Molloy-Vickers provides an brief history of the German chain which explains the reason for the warning..

"The 9B chain (old German chain) was set up for air use but it gave poor coverage on its north coastal areas. Decca converted it to Mk 10 system somewhere around 1964 in an effort to improve air useage for Mk 19 receivers and their follow-ons. The chain used to be run by German Air Traffic Control (Bundes Flugsicherung) but they were rapidly losing interest as there were few German national users. British Airways liked it and so did the UK Ministry of Defence. When the Frisian Islands chain was installed it took the 9B chain frequency in order to have good coastal coverage and the German chain switched to the half chain frequency of 3F which is only suitable for the later types of receivers. Obviously, any receiver switching to 9B after the changeover and using the original German charts would see garbage! After this change, chain 3F  was no longer of any marine interest.

The "new" German chain was also to be run by Decca under contract to the German Ministry of Defence Various additions were installed to cover their particular requirements. The original chain construction used massive Telefunken transmitters (as in radio station type systems) rather than the current multiple modular Decca designs with separate power supply systems. The slaves were unattended at night, instead, relying on a remote alarm system to call in an operator from his home to service any alarm . This was not permitted on a Decca managed  station in that era! Back then , the station was sealed and was automatically flooded with CO2 in the event of a fire alarm".

A map of the German chain is available here.


Bombay and Calcutta were contracted in 1959 according to Decca records. Bombay opened in 1962 while Calcutta became operational in 1964.

Bombay Chain 7B
Savarkundla Master 85.3650  kHz 21.3377N, 71.3052E 
Bilimora  Red 113.820 kHz 20º45'40"N, 73º02'17"E
Veraval  Green 128.048 kHz 20º57'07"N, 70º20'13"E
Dhrangadhra Purple 71.138   kHz 23º00'14"N, 71º31'39"E

Calcutta Chain 8B

Stations were located in the States of Orissa and West Bengal.
Balasore  Master 85.5450   kHz 21º29'08"N, 86º55'18"E
Patapur Red 114.0600 kHz 20º50'28"N, 86º 27'28"E
Bishnupur  Green 128.3175 kHz 23º04'06"N, 87º 19'00"E
Diamond Harbor Purple 71.2875   kHz 22º10'18"N, 88º12'25"E

Salaya Chain 2F

This chain was installed in 1978 specifically as a navigation aid for the Gulf of Kuchchh marine traffic using 1880 series equipment.  It was officially opened on February 15, 1979. Very Large Crude Oil Carriers (VLCCs) brought crude oil from the Persian Gulf to the refineries in the state of Gujarat and in particular through the deep water channel to the off-shore oil terminal at Salaya. Stations sites in the Salaya chain were all near rural villages that were some considerable distance from a major city.
Mandvi  Master 84.5550    kHz  22° 52' 26.80"N,  69° 24' 00.02"E
Kuranga Red 112.7400  kHz 22° 03' 29.92"N,  69° 10' 29.74"E
Dhuvav (Dhuwao) Green 126.8325  kHz  22° 28' 48.54"N,  70° 07' 43.09"E
Naliya  Purple 70.4625    kHz 23° 15' 04.32"N,  68° 49' 00.03"E


It was from India that the first non-European Decca chains were ordered.

The Decca Navigator Co. of U.K.  was contracted in 1955-56 to establish a hyperbolic position fixing system in India. The Bombay and Calcutta chains of four stations each were established between This chain used the 820 series tube equipment when first installed between 1958-62.  The production of Decca Lattice navigation charts was taken up in 1967 by the Indian navy with the first of the series covering the approaches to Paradeep Port. These were first published in April 1968.

The Director General  under the Department of Lighthouses and Light-Ships was the sole authority for administration and management of light-houses and their principal navigation aids such as Decca Navigator. There were three chains in India.  The Department of Lighthouses and Lightships is a subordinate office under the Ministry of Shipping and headed by the Director General of Lighthouses and Lightships.  The Headquarters of the Department of Lighthouses and Lightships is situated at Noida. Decca's main supporter was Mr. Lahiri of the Indian Lights Authority as it was known at the time.

David Jones describes one incident while in working for Decca in India. "Base lines were relatively short but journey times between stations were measured in many hours depending on circumstances. Our team from Diamond Harbour once made the 50 mile drive back to Calcutta in an elderly Ford car which had a broken fuel pump. Every couple of miles, the driver would stop the car,   remove the carburetor float chamber cover and pour in another cupful of gasoline".

In 1992, Bombay and Calcutta  were replaced by Loran-C chains of three stations each. The Salaya chain closed as of  December 2000.

All three Indian chains can be viewed here.


In 1974, The Decca Navigator Company signed a contract with Perusahaan Pertambangan Minyak Dan Gas Bumi Negara (PERTAMINA). This organization  acted on behalf of the Indonesian Government for the supply of a Decca chain to be installed on the Sumatra coastline in the central area of the Malacca Straits. It was to be called the Dumai Chain.

The layout of the chain was configured to provide accurate navigation in the approaches to the new oil terminals which were being  developed at Dumai and Sungaipakning. In addition, it going to provide accurate coverage over the whole central area of the Malacca Straits. The installation of a Decca chain in this important and hazardous seaway marked a significant step forward in the march of marine safety in its day. For the Decca company, there was a lot of concern as to how they were going to erect masts in the swamps with no solid footings. By the late 1970's, all hopes of building the chain were totally dead. Dave Baker of Decca bought all the equipment back from the Indonesians (PERTAMINA) and sold the master and two slaves to the Iranian PSO (Ports and Shipping Organization) for the proposed Strait of Hormuz Chain. Due to the Iranian revolution, the Strait of Hormuz chain was never built . The Purple Slave 1880 cabinet intended for Hormuz instead saw active service as the Purple slave of the Holland Chain in Thorpeness, Suffolk, UK.

Select this link for a map of the proposed Dumai chain.

Bandar-e Deylam Master 85.0050    kHz 30°1'7"N,  50° 9'29"E
Abadan  Red 113.3400  kHz 30.4° N,    48.2° E
Bushire Green 127.5075  kHz 28° 58' 38"N, 50° 51' 9E

In the North Persian Gulf Chain 5C, all the stations were located in Iran and based around the port of Abadan. Both chains in the Persian Gulf were operated by The Middle East Navigation Aids Service (MENAS). It was established in 1950 to serve the maritime industry in the Arabian Gulf, but it can trace its origins back to 1911 when tanker shipping entered the Gulf to collect cargoes of oil. MENAS, an independent, not for profit organization, while registered in the United Kingdom, has its centre of operations in Bahrain at a base established in 1950 following the donation of land in perpetuity by the then ruler, the late Amir, HH Shaikh Salman bin Hamad Al Khalifa. an entirely independent authority having no national sponsor or commercial owner. Revenue is drawn solely from navigation dues paid on vessels above 2,000 Net Registered Tonnage (NRT) using Gulf waters and, this revenue is invested for the safe navigation of shipping passing through the Gulf. Chain 5C provided coverage for vessels using the waters along the coastline of Iran.

John  Molloy-Vickers, one of the installers for the North Persian chain, gives his perspective on the installation. " I spent Christmas 1960 and a few months thereafter in Persia helping to install the North Persian Gulf chain. Nobby Clarke, Ernie Easter and Reg Odams were the principals from our department. The problems were huge. All the equipment for the three stations had been dumped in a yard after delivery to the National Iranian Oil Company in Abadan. Although they had been carefully marked and labelled in the UK,  by the time they were ready to be deployed it was nearly impossible to tell whether a crate contained an air conditioner, a toilet bowl or a transmitter.

Equipment was loaded in some cases onto landing craft to send it on its way. It was a major exercise since we had to start from scratch and build complete stations with all facilities for operating staff and servants. We became plumbers, electricians, sewerage experts and medical attendants to the locals in a very short time. We initially lived in tents with scorpions and snakes for company. When we had the living quarters built, goats were slaughtered on the back door step by our Indian cooks etc. Through our interpretter at Deylam I recalled that one of the locals  asked for sidecutters. When asked what for, he said to "cut off his wife's finger" to recover her ring before he buried her in the cemetery next door to our station.

One day, I rather stupidly jumped into the Shatt al Arab waterway at Korramshur to cool off and surfaced next to a dead cow. I was keeping a wary eye on the Iraqi guards who always watched us from the other side and I was not looking out for flotsam.

I believe the chain closed on May 1, 1980".

Phil Jones, a former Decca employee who maintained the Persian Gulf Chains in the late 1970's provides this account of the situation in Iran around the time the Shah of  Iran fell.

"Things got scary just before the fall of the Shah and the rise of Ayatollah Khomeni. Many of the knowledgeable expatriates simply moved away but the Decca crews were considered essential. Logistical problems arose in Iran where it was never easy to get parts under normal circumstances. Procurement of vacuum tubes was especially difficult. I remember smuggling some in my suitcase on a return trip from UK on one occassion.

Going into towns or villages as a visible Westerner was risky to say the least. During the American hostage crisis,  a lot of hatred developed against the west. Once,  we had to flee and hide for our lives on a routine shopping trip just to get groceries. Back in those days it was impossible to make a phone call locally,  let alone internationally and it took about 3 to 4 weeks to get a letter from home. All our communication between stations was made possible through short wave radio. We all became radio ham experts. By that, I mean we could easily understand each other no matter how garbled the voice was at the other end. Sometimes we did take advantage of this with our regional manager.

When we were were stationed on Lavan Island which was the best location in Iran for day to day living, we would get instructions from our area manager in Khorramshar ( near Abadan). If we did not like what he was asking, we could easily say he was fading out and could he repeat that!! After several times of repeating, he would give up but I don't think he believed us. Life in Iran was tough to say the least back then and it gradually got worse as the new Islamic-style regime started to grip the country. Towards the end, getting out of Iran was probably the most dangerous thing for me but that's another story.

The bugs were big and plentiful. (ie camel spiders,  scorpions and even snakes). .On the station at Lavan Island, one snake even came to visit me sidewinding under the toilet door. As an ex-boy scout, one has to be prepared but under these circumstances I never knew how to defend myself against an irate sandviper with pants down and a toilet roll! I suspect it was actually planted by a disgruntled local employee -  the diesel coolie, who I made do an honest days work each day when I was there. I must say that some of the weirdest and most potentially dangerous experiences happened to me while I maintained the Persian Gulf Chains".

Phil also relates this story about the Master station failure Bandar Deylam. " It happened just before I joined Decca in the Gulf. One engineer was on a sleeping watch when the alarm sounded in the middle of the night. He ran into the station and saw that all 807 transmitter amps were blowing fuses fast and furious. As soon as he replaced the fuses they blew again. Then out the corner of his eye he noticed no aviation lights on the mast. The reason - the whole 300 foot mast had come crashing down in the middle of the night. Apparently the construction company used sea water to mix the concrete for the mast anchor blocks (to save money) when the mast was put up several years earlier. So it was just a matter of time before the concrete failed.

After this "incident" the station was completely overhauled. Since it had such a good maintenance history prior to the crash,  it was one place where you could actually get a good nights sleep. I guess the duty station engineer who witnessed the mast come down also got a few good nights sleep after that commotion.

Often, going off the air was the result of a diesel failure. Those 28 year old Listers were good but sometimes unpredictable. When I was on a sleeping watch, the thing that often woke me up was the total silence of not hearing the air conditioners running. You would get up in a daze, sometimes you were lucky and the station was still on the air; sometimes not. Going from a deep sleep to being fully awake and in 3 minutes hand cranking an old 6 cylinder Lister (on decompression) could only be done if you were under 30. I think now that would be case of major heart failure!

Looking back I often wonder  how those stations were as reliable as they were. Logistics was always difficult. Even diesel fuel delivery at Bandar Deylam was by donkey! "

Phil Jones, by the way,  has been involved in home audio since he was thirteen years old. While stationed in the Persian Gulf with The Decca Navigator Company, he designed and built speakers to pass the time away. In the UK, many folks know him as the dude who designed and founded Acoustic Energy (of AE-1 and AE-2 fame), then with Boston Acoustics (Lynnfield speakers), followed by the founding of Platinum Audio. In 1998 AAD (American Acoustic Development Ltd.) was born with a manufacturing plant is located in China. This is where Phil spends his time now. In August 2003, Phil will be moving to the St. Louis MO, to look after his interests  in  PJB (Phil Jones Bass Inc), an organization dedicated to making very high performance bass guitar amplifiers. One model is all tubes using four 813 transmitter tubes.

A map of the Northern Persian Gulf chain can be seen here.
Also see the U.A.E. section for more information about the Persian Gulf chains.

The Irish Chain 7D was operated by Bord Iascaigh Mhara (Irish Sea Fisheries Board) for mariners sailing on the west and south coasts of Ireland. All stations were located within Ireland. Chain 7D was formally opened on May 31, 1973.
Galway (Oranmore) Master 85.450   kHz 53.250º N,  08.930º W
Ballydavid  Red 113.933 kHz 52.200º N,  10.367º W 
Dungloe  Green 128.175 kHz  54.883º N,  08.383º W 
Youghal (Ardmore) Purple 71.208   kHz 51.950N,  07.750º W

Select this link to see a map of the Irish chains and the towers. The mast at Galway (Oranmore) is apparently gone.


ROME: Chain ID: ??

In the late 1950's, the RAF lobbied NATO to establish a Decca Navigator chain in Italy because the RAF had already installed Decca in some of its low-level Canberra B8 aircraft. A two pattern Decca evaluation chain was therefore constructed for the Rome Control Area, however the exact date of its opening is not known at this time. Master and Red stations were situated on the Italian mainland with the Green slave on the island  of Sardinia.

Walter Blanchard flew on some of the flight trials and demonstrations. "Apart from demonstrations for Italian civil aviation authorities, we also flew a considerable number of military trials based at the Italian Air Force base in Pratica di Mare, near Rome. The main monitor station for the chain was located there. We used an IAF Fiat G91 fighter with an experimental set-up of three antennas spaced equally round the fuselage to get around the loss of signal when the aircraft performed manoeuvres. The tiny cockpit was even fitted with a Flight Log!.  It was a fairly successful trial and later on  we transferred the equipment to a USAF F-101 and carried on with trials in the UK. These trials  were supported by NATO who were looking for a low-level navigation system in Italy, but nothing ever resulted from them and I'm not sure why. These trials were triggered by the RAF who at the time had installed Decca in some of its low-level Canberra B8 aircraft. I also flew the trials in those aircraft. I believe the costs of the Italian chain were borne mainly by NATO but Decca took advantage of it to perform civil demonstrations as well".
Pratica di Mare (south of Rome) Master ? 41° 40' 0 N, 12° 28' 60 E
SE of Turni, Italy Red ? ?
Venefiorite (north east) Sardinia Green ? ?

The continuous growth of commercial air traffic and the introduction of more turboprops and turbojets increased the problem for air traffic control in the Rome Control Area in the late 1950's. Aggravating the situation were relatively inaccurate radionavigation systems which formed the basis of air traffic control in this area.  The mixture of aircraft types required complex routing and radar was insufficient to get the whole job done. To demonstrate the capabilities of the Decca Navigator system in the cockpit, two demonstration fights by Decca's corporate Valetta aircraft were arranged for October 14/1959. There were many other flight demonstrations as well.
For unknown reasons, the chain did not persevere so its closing date is not known at this time.


A demonstration chain was set up in Sicily as reported in the November 1969 issue of Decca Navigator News.

For more information on Decca Italy, select this link.



Japan was a land of opportunity for Decca because it relies on the sea for its food supply and fishing is a major industry. Because Japan lacks mineral resources, oil and steel have to be imported therefore the sea is very vital to the country's economy.

Japan was an early user of the Decca system having bought its own survey chain in 1960. Also, it was an early European chain user - ships picking up receivers from Mediterranean ports when entering the area and leaving them behind when returning to the Far East.

When Decca made made the initial contact into this marketplace, the company found a few knowledgeable individuals anxious to learn more about the system. There were not many but they were influential. The big names were Shimasue and  Kiyono. Mr Kiyono is still very active in Japan and his company, SENA  started renting Decca-licenced, Japanese-made receivers starting around 1966.

In the mid-1950's, the basic problem for Japan was a shortage of money but as the country's financial situation improved so did Decca's chances of establishing chains. . In 1964, with Japan just beginning its up-turn of Navigator, Decca signed agreements with the Government of Japan and with a number of commercial organizations. These included Kobe Kogyo (now Fujitsu) as the manufacturing licensees. All of the relationships were most cordial and long lasting. Over the years the Japanese Government built six chains so that the whole of Japan was covered.

Japan holds the distinction of being the last bastion of Decca having closed down the Hokkaido chain in March 2001. This was one year later than the UK closure. Hokkaido was also the first Decca chain to open in Japan.

The SENA Company kind enough to provide details for all six Japanese chains. To see full details on the Japanese Decca chains, select this link.


Finsterwolde,  Netherlands  Master 85.720   kHz 53.200ºN, 07.100º E
Hoejer, Denmark  Red 114.293 kHz  55.017ºN, 08.717º E
Heiloo, Netherlands Green 128.580 kHz 52.600ºN, 04.733º E 
Zeven, Germany  Purple 71.433   kHz 53.283ºN, 09.267ºE


Bob Peters, who was previously a Decca maintainer,  provides some information on the Dutch chains. "I worked 16 years on the Green Slave of chain 9B until the conversion in 1985 which permitted automatic operation and remote control.  The stations of the Dutch Chains were not maintained by Decca. Instead a Dutch concern  provided maintenance.

The, was built in 1968 for merchant, fishing and yachting purposes and the owner of the F.I.C. was the Directorate General for Public Works and Water Management (RWS) owned and managed the chains. The Frisian Islands Chain covered the North Sea,  north of the Netherlands and Germany and west of Denmark.

Bob goes on to describe the power system for the Green slave. Under normal conditions, power to the site was provided by the public power system. (380 volts 3 phase from a 10.000 volt step-down transformer). A 380 volt feed supplied the input for two motor generators whose output was 600 volt DC for the transmitters, 380 volt AC for the phase controls and Rasme, a 220 volt DC output and a 50 volt DC output both for recharging the batteries. During a power outage, the 200 V dynamo became a motor whose power source was the 220 volt battery bank. After some time,  a 6 cylinder Lister diesel generator took over. In all, there were two motor generators, two 220 volt battery banks, two battery banks of 24 volts each

Before conversion, the F.I.C. was controlled from the Master station which was manned 24 hours a day while the Green slave was only staffed during normal business hours. Two men worked at the Green slave with a one day on, one day off work schedule.   For off-hours coverage, each man was equipped with a special alarm receiver at home. The station raised the alarm by a sudden drop of the power from the 9F transmitter just after the Multipulse period.

Around 1985, all the stations F.I.S. the stations were converted to run automatically and under remote control.
Although  a control desk was built into the Master station, all the information was sent to Hoek of Holland over a leased telephone line to a second control desk.  The control of chain 2E was therefore located in Hoek of Holland,  the entrance to the port of Rotterdam.

Slave station Purple in Zeven, Germany was located between Bremen and Hamburg at coordinates  53° 17' 07"N, 09° 15' 49"E.  Providing coverage for the North Sea, it was decommissioned in December 31, 1999. The main antenna had a mast height of 93 meters while the backup was slightly shorter at 46 meters. On hand evidence suggest it was also the Green slave for the German chain 3F.

An interesting note was spotted in a Decca technical publication dated 1973." WARNING - Although the
Frisian Islands chain is using the same frequency as the old German chain, namely 9B, the ground stations are not in the same positions and therefore the old German charts cannot be used with the Frisian Islands chain.  See notice to Mariners 1977(p) of 1967 ". Something obviously happened with the chain assignment,. Can anyone explain this mystery?

Gilze-Rijen, Netherlands Master 84.550   kHz 51.617ºN,  04.917ºE
Heiloo, Netherlands Red 112.733 kHz 52.583ºN,  04.733ºE
Westdorpe, Netherlands Green 126.825 kHz 51.233ºN,  03.833ºE
Thorpeness, England Purple 70.458   kHz 52° 10' N,  01° 37'E

The Purple slave Thorpeness was added after chain 2E was established since it does not appear in the initial chain  listings. One correspondent said he looked after this slave from 1991 through 1994. This chain serviced the  area of the Netherlands known as Europort.

With the help of Decca, large crude oil tankers could enter the Hoek of Holland through a virtual "canal" in the sea. Initially built without a Purple slave,  it was eventually added and was located in Zeven, Germany. Until the Purple station was functional, the master station also transmitted the Purple signal. Since there was a bend in this canal and the hyperbolic lines of the Red and Master and Red and Green stations criss-crossed over the canal, a special accessory on the receiver made it possible to use the Red and Green slave only for navigation. Because the Dutch were very keen users of the system, they developed their own high accuracy differential receiver for pilot vessel use. This was known as the "Brown" receiver because Red and Green produce brown when mixed.

On Saturday the 16 April, 2011  at 10.00 o’clock  the Decca transmitting aerial of Green 9B was intentionally demolished.  Red 2E came down at 13.00 hours, twelve years after Decca was switched off. The transmitter buildings are still there. Green and Master of 9B are used as clubhouses by a motorclub.

To view a map of both Dutch chains and the Finsterwolde mast, select this link


Ikorodu  Master 85.6400   kHz 6 º 39'N,   3º 35'E
Abigi Red 114.1867 kHz 6º  30'N,   4º 23'E
Badagary Green 128.4600 kHz 6º  25'N,   2º 56'E
Abeokuta  Purple 71.3667   kHz 7º  17'N,   3º 29'E

? Master 85.4600   kHz ?
? Red 113.9467 kHz ?
? Green 128.1900 kHz ?
? Purple 71.2167   kHz ?

Station names unknown at this time.


These chains were proposed but not built.


The economy of Nigeria has been closely linked to the oil industry and  the discovery of considerable reserves brought about many changes there. For many years,  there had been exploration programmes using small Decca survey chains but as the development of the industry took place it became necessary to install full.size, non-restricted user chains. Four such chains were initially commissioned.

In the 1970's, important oil developments off the coast of Nigeria were raising the urgency for effective and safe control of marine traffic. Uncontrolled shipping would present a growing hazard to oil rigs, loading terminals and to the large number of tankers coming in to the area. A series of areas prohibited to normal traffic would be introduced to protect the loading terminals and rigs and a system of traffic routing instituted to ensure that the regulations were not violated. Tanker routes to and from the loading areas would be laid down with a zone for coastal traffic inside the restricted areas.

The Decca Navigator company intended to undertake all the necessary work including the selection, surveying and clearing of sites, the erection of antennae and the installation of technical equipment. At the end of the project, complete operating chains would be handed over to the Federal Ministry of Transport to be manned by Nigerian engineers trained by Decca in the United Kingdom. The four chains were intended to give contiguous coverage along the Nigerian Coastline using 1880 type equipment.

The Lagos chain consisted of the Master station at Ikorodu to the North of Lagos, the Red slave at Abigi along the eastern shoreline of the Lagos Lagoon, the Green slave at Badagary near the Benin Boarder, and the Purple slave at Abeokuta, about 60 km north of the master station. These slaves were intended for unmanned operation with  planned visits of only once a month and diesel generator maintenance at three month intervals. Diesel generators were the only source of power for the Nigerian chains. A monitoring station was located at Agbowa, about 7 km north of the master station.

According to David Jones, a former Decca employee, only two out of the four chains were ever built and those were a struggle. Rampant corruption and dishonesty plagued the project. Lagos and Rivers operated for a short time but never went into public service.  It is believed that the Nigerian Chain was the last Decca chain ever built.

The dramatic changes in world oil prices were paralleled by Nigeria's internal political problems. There were many difficult years for Nigeria and these lead to difficult times for the chains. As a result, the Lagos and Rivers chains shut down before going into commercial service.

Select this link to see the Nigerian chains and a photo of the signing of the contract.


The contract to establish six Norwegian Decca chains  was signed in September 1965 and the chains were formally opened on May 14, 1968.


Finnmark was Norway's first chain and it was opened on May 27, 1967
Bøerselv, Norway Master 85.4550     kHz 70º23'28"N, 25º30'14"E
Kirkenes, Norway  Red 113.9400   kHz 69º41'19"N, 30º03'14"E
Vannøy Øst, Norway Green 128.1825   kHz 70º06'20"N, 20º07'07"E
Nordkapp, Norway  Purple 71.2125     kHz 71º09'36"N, 25º45'21"E
  Orange 116.7885   kHz  


Helgeland was initially 10B then became 9E. The frequencies shown below are for the 9E chain.
Dønna, Norway Master 85.8100   kHz 66.200ºN, 12.467ºE
Røst, Norway Red 114.4135 kHz 67.533ºN, 12.133ºE
Rørvik, Norway Green 128.7150 kHz 64.917ºN, 11.167ºE
Mo Rana, Norway  Purple 71.5083   kHz 66.283ºN, 14.167ºE
  Orange 117.2737 kHz  


Lofoten was initially 3F then became 3E. The frequencies shown below are for the 3E chain.
Andøya, Norway  Master 84.7350   kHz 69º08'45"N, 16º01'53"E
Vannøy Vest Red 112.9800 kHz 70º14'51"N, 19º30'05"E
Røst, Norway Green 127.1025 kHz 67º31'44"N, 12º09'30"E
Narvik, Norway Purple 70.6125   kHz 68º27'57"N, 17º06'02"E
  Orange 115.8045 kHz  

Skarsoy, Norway  Master 84.9150     kHz 63.333ºN, 08.450ºE
Rørvik, Norway Red 113.2200   kHz 64.917ºN, 11.167ºE
Stad, Norway Green 127.3725   kHz 62.200ºN, 05.133ºE
Berkåk, Norway Purple 70.7625     kHz 62.833ºN, 10.050ºE
  Orange 116.0505   kHz  

Stad was shared with the Vestlandet chain.

Aagotnes, Sotra Island, Nor.  Master 84.1950   kHz 60º24'24"N, 05º00'34"E
Stad, Norway  Red 112.2600 kHz 62º11'35"N, 05º07'31"E
Shetland Island, Scotland Green 126.2925 kHz 60º02'54'N  01º14'33"W
Stavenger, Norway Purple 70.1625   kHz 58º47'15"N, 05º32'42"E
  Orange 115.0655 kHz

The village of Aagotnes on Sotra Island in Western Norway was home a Decca site from 1966 to 1999. The chain was closed down on  Jan.17th, 1997 at 1200 noon. Stations in this chain used 1,200 watts of power.
Stavanger (Hodne) was closed down was January 22nd, 1997.

The Green slave of this chain was located on Shetland Island in close physical proximity to the Green slave of the North Scottish chain 6C with the Green carriers only 1.485 KHz apart. Can anyone comment as to why Decca did it this way because it's the only example in the entire network?

More on the Norwegian Decca chains can be viewed  here .


Barra, Scotland  Master 85.635   kHz  56º59'N, 07º25'W
Kentra Moss, Scotland Red 114.180 kHz  56º45'N, 05º49'W
Butt of Lewis, Scotland Green 128.453 kHz  58º30'N, 06º16'W
Dungloe, Ireland  Purple  71.363  kHz  54º53'N, 08º23'W


The Hebridean chain first transmitted test signals in Dec 1976, and went on the air in 1977. It filled the last remaining gap in coverage around the UK by providing coverage for the North and North West coasts of Ireland, off the Hebrides and improved accuracy in the Minches. It was configured for dual chain operation

Along with the Northumbrian chain, it used re-furbished  thermionic valve equipment bought back from the
USA. The USA had two experimental chains - one in California which was used for airborne trials, and one around the Bahamas reputed to have been used for submarine navigation. It is not certain which chain ended up at which site.

The Hebridean chain shared transmitter locations with Dungloe of the Irish chain, and the Butt of Lewis of the North Scottish chain, so only two new sites were needed - Barra and Kentra. These stations were designed to withstand the fierce winds and they looked like crofters houses. They were built by the same Berwick-on-Tweed contractor that built the Northumbrian stations to the same design.  Transmitter sharing meant synchronization of all these chains, which was done by using the Rubgy time signal.

The Barra master was built during the glorious summer of 1976, when the locals were amazed at the speed of construction. Having built the Northumbrian stations previously had a lot to do with this. The stations of this chain were all continuously manned because the economics were such that this was a cheaper option than the capital cost of remotely controlled solid-state stations. Of course, the shared stations were already manned and had the full infrastructure in place.

Photos of the Hebridean chain can be viewed in this section.

Kirkwall [a.k.a. Dounby], Scotland  Master 85.1850   kHz 59º04'N, 03º15'W
Butt of Lewis, Scotland  Red 113.5800 kHz 58º30'N, 06º15'W 
Lerwick [a.k.a. Shetland], Scotland  Green 127.7775 kHz 60º10'N, 01º 11'W 
Peterhead, Scotland Purple 70.9880   kHz 57º31'N, 01º 51'W 


The Decca station in Dounby started transmitting from a group of wooden huts on September 1, 1955. The base was set up by Ken King, who had been running a station in the south of England. The first person to take charge of running operations in Dounby was Harry Cordock along with Gordon Pirie who lived in Stenness, and Davy Johnstone from Dounby. The last station manager was Jim Anderson,  who recalls those early days.

“I joined Decca in May 1956. It wasn't supposed to be officially open until later, but the fishermen were in such a hurry that we opened it when it was still manually controlled. We had to take readings and check other things to make sure everything was all right. After that, you were just waiting there in case anything went wrong. It was a case of diving at the switches and doing something about it if anything happened.”

“Dounby [Kirkwall] was the North Scottish Master station, with ‘slave’ stations in Butt of Lewis, Peterhead and Shetland [Lerwick]. Jim added: “I think there were four engineers to begin with, but it grew to five plus a handyman when we moved into the new building in January 1958. The first and second engineers lived on the premises. Harry Cordock was first engineer, and Duncan Bell was second engineer. When Duncan returned to Edinburgh he was replaced by Ken MacInnes from Stromness. That was when the transmission system became reasonably automatic. You still had to be there, but you could turn your back on it for a few seconds. It was a 12-hour shift system we worked, and every 15 minutes we had to take readings off the receivers. The figures were recorded in logs in triplicate, even though there was a machine recording them as well.”

Tommy Mainland joined Decca in December 1966 in Dounby. He remembers what it was like working a shift system, when living on the station. “When I joined, we used to do 12 hours on a day shift, from 9 in the morning till 9 at night. The next day, you went on at 9 at night and worked till 9 in the morning, and then you “allegedly” had two days off. I worked that shift pattern for a while, and then eventually we changed that to one week at 9 to 5, a week of 5 till midnight, and a week of midnight till 9 in the morning. It ended up that when we got “sleeping” night watches, we did 24 hours on, and 48 hours off.”  Jim Anderson remarked: “Eventually the station became more automated, we were able to sleep at nights.

George Grieve joined Decca at Peterhead in January 1967, one month later than Tommy Mainland. George recalled the shift system he had to cope with.

“Peterhead was the ‘purple slave’ station. We just did 24 hours on, 48 hours off. But during the time off at Peterhead we were always very busy doing the marine servicing side of it - with the navigators on the fishing boats, which we also did up here, but not in such large numbers. If they broke down when they were trawling,  they would pull up their nets, come ashore and get it fixed, rather than chance going without it. We installed the equipment on board the boats and serviced it. It was 24 hours a day. They were paying for it, and they expected to get it. If the system  broke down at 3 o’clock in the morning, you were expected to be there.”

The whole system became totally automated in January, 1994, and the individual stations were left unattended except for maintenance work carried out by a locally-based engineer. In Dounby’s case, that person was Jim Anderson. “I've been on call 24 hours a day. I've had to go to the control centre which is based at the lighthouse headquarters in Edinburgh, to do shifts there from time to time. I always come out here once a week, although the requirement was only once a quarter to do the maintenance, but I liked to keep it in good order.”

The non-essential staff were kept on until the end of September, 1994 stripping out the entire supply of technical equipment from the main building, and vacating the living quarters, to be replaced by a self-contained air-conditioned aluminum clad cabin alongside, housing miniaturized equipment. Neither Tommy Mainland nor George Grieve felt it hard to leave the Decca station for the last time when they were made redundant at the end of September, 1994. Tommy commented: “It wasn't difficult, because we'd had so little to do for the rest of that year. It seemed strange the building being there, but doing nothing.”

In its heyday, Decca could promise a career for life, providing regular training in electrical work and other aspects of the company's many interests. Jim Anderson remembered those halcyon days.

 “We had a Decca school which was at Brixham in Devon, and they sent us on courses from time to time. The Admiralty weapons and communications company Racal took over Decca in 1981 or so. It was said that they wanted to acquire Decca’s radar company, rather than the avionics side of the business. It was all going fine until a Danish company started making receivers for fishing boats which operated with Decca’s navigation charts, but they didn't pay any rental for using the system.

 “A court battle followed, Decca lost the exclusivity, and that started the beginning of the end. Income started to dwindle. Eventually, the Ministry of Transport stepped in, and got the lighthouse authorities to take us over. That would have been the early 1990s.”

Jim went on to talk about the final switch-off for the station. “The equipment here is of no use to anybody else. That's the end of it. A skip is coming and we'll throw everything out. We have to get rid of the condensers in the  coil house, and there's oil in them which has to be checked before moving anything  there. Alton Tait is taking over the cabin and the engine, so we'll leave the control  gear connected up, and just disconnect our gear from it.”
Tuesday, April 4, 2000 marked the end of an era for post-war technology in Orkney, with the complete  shutdown of the Racal-Decca navigator station in Dounby.

The Green slave of this chain was located in Lerwick in close physical proximity to the Green slave of the Vestlands chain 0B with the Green carriers only 1.485 KHz apart! Can anyone comment as to why Decca did it this way because it's the only example in the entire network?

Select this link to see a map of the Scottish chains.
Photos of the North Scottish Chain can be seen here.



In the late 1940's the South African Government conducted a series of tests to determine the effects of the local conditions on the propagation of Decca signals. George Hawker of Decca spent several months in the area and much was learnt. Decca kept good contact with all concerned in South Africa and this was rewarded with the building of five chains in the mid and late '60's.

General Wilmott, the Supreme Commander of the South African Forces and General Martin, the Head of the Air Force were closely involved in the Navigator procurement while Colonel Broadhurst and an engineer named
Wadley conducted the initial trials. It was Wadley who developed the communication receiver which established the technical base for much of Racal Communications equipment.

The South Africa chains were heavily used by both coastal and helicopter traffic. In the early 1970's, Decca established a separate company in South Africa to sell and support it's products. Through expediency, this company became virtually self-sufficient in it's operation and was very well run. Much of the South African Defence Force relied upon Decca products for navigation and communication.

A map of the South African chains, photos and chain data  can be viewed here.


Santiago Insua Fernandez,  whose father was employed as a Decca maintainer, provides a brief outline of the Spanish chains along with some photos.

North-West Chain 4C
San Xoan de Rio,  GALICIA Master  83.8300 kHz  42.383ºN, 07.283ºW 
Noia, GALICIA * Red 113.107  kHz  42.733ºN, 08.917ºW
Boal, ASTURIAS Green 127.245  kHz  43.450ºN, 06.833ºW
Vitigudino, CASTILLA LEÓN Purple 70.6920  kHz  41.017ºN, 06.433ºW 
* Lousame is the name of the nearest village to the former 4C Red station, but it's a village of only 100 habitants. The principal village in the area is Noia (18,000 habitants) and this is the name that is recorded in all official documents. 

Southern Chain  6A

This chain was designed to serve the narrow waters around Gibraltar and the ports of Huelva and Algeciras. The master station was about 60 miles north of Malaga.
Setenil de las Bodegas, ANDALUCIA Master 85.1750   kHz 36.867ºN, 05.133ºW 
Padul, ANDALUCIA (near Granada) Red 113.5667 kHz  37.033ºN, 03.683ºW 
Los Barrios  ANDALUCIA Green 127.7625 kHz  36.183ºN, 05.483ºW 
Rociana del Condado,  ANDALUCIA
(near Seville)
Purple 70.9792   kHz 37.300ºN, 06.600ºW 


The installation of Decca Navigator in Spain in 1977/78 was a joint venture between The Decca Navigator Company and Marconi Español. Both Spanish Chains had an effective range of 240  miles. All sites used the 1880 series station equipment which was also designed for unattended operation. System monitoring was based on a remote receiver at a small mountain village called Olvera and the data was sent via microwave link to the master station. Much of the ancillary equipment was made or purchased by Marconi and they installed most of it. Once the chain was completed, the Decca vessel, MV Navigator was used for some of the system trials

In Spain,  the government decided to have manned Decca sites. The personnel who maintained the Decca chains were employed by the Special Public Corporation, an arm of the Spanish Public Works Ministry. Slave stations had one dedicated maintainer while master stations had four people. Most of the maintainers lived on the station properly along with their families. In 1994, the Spanish Government announced that the Spanish Chains will remain in service until the year 2000. One year later they  closed Decca and all the employees of the Spanish Chain were transferred to the Spanish Public Ports. This semi-private corporation was called "Ente Publico de Puertos del Estado Español ".

The North Spanish chain became well known as the one where a station engineer froze to death while trying to reach the building during a winter storm. He was found crouched behind a wall within sight of the buildings.

For photos and a map of the Spanish chains, select this link.


Proposed in 1978, the chain was never built due to the Iranian revolution, however the chain appears on a Decca document published in 1982. For additional information and map select this link.


Both the North and South Baltic chains were in Sweden.

North Baltic 4B
Nynäshamn, Sweden  Master 84.825   kHz 58°56’42.95”N   17°57’31.13”E
Åland Islands, Finland Red 113.100 kHz 60°07’12.43”N   19°49’29.08”E
Ar, Sweden Green 127.238 kHz 57°54’52.41”N   18°57’29.28”E 
Björkvik, Sweden Purple 70.688   kHz 58°50’46.10”N   16°34’22.26”E

The North Baltic chain was made operational in October 1957. Prior to 1970, the Red slave was located at Rådmansö, but it was moved  to Åland in 1970. Ar is a small village at the northwest tip of Gotland Island.

South Baltic 0A
Holmsjö, Sweden  Master 84.100   kHz 56º 27' N, 15º 40' E (56.450ºN, 15.667ºE)
Burgsvik, Sweden  Red 112.133 kHz 57º 03' N, 18º 15' E (55.400ºN, 14.183ºE)
Sandhammaren, Sweden Green 126.150 kHz 55º 24' N, 14º 11' E (57.017ºN, 18.250ºE)
? Orange ?

Chain 0A opened as a multipulsechain but no information is available regarding the Otange slave.


By the early 1960's, the old Swedish chain had become  the North and South Bosnian Chains.

The North Bothnian 5F chain consisted of a master and two slave stations in Sweden while the third slave was in Finland. It came into commercial service in June 1962.
Lövånger, Sweden  Master 85.095   kHz 64°20’55.67”N   21°20’55.20”E
Gamla Karleby, Finland  Red 113.460 kHz 63°51’51.36”N   23°10’58.24”E
Kallax, Sweden  Green 127.643 kHz 65°31’45.86”N   22°04’08.01”E
Järnäs, Sweden  Purple 70.913   kHz 63°28’46.29”N   19°39’13.41”E

The entire South Bothnian 8C chain was located in Sweden. It came into commercial service in June 1962.
Njurunda, Sweden  Master 85.550   kHz 62°16’47.55”N   17°25’31.13”E 
Skutskär, Sweden Red 114.067 kHz 60°37’17.71”N   17°26’34.20”E
Järnäs, Sweden Green 128.325 kHz 63°28’46.29”N   19°39’13.41”E


In 1974, it the Swedish government requested an upgrade for both the North and South Bothnian chains which would give them Multipluse capability. In addition, a  new chain configuration was requested by the Board of Shipping and Navigation of the Swedish Government. Decca carried out some special development to provide a dual Slave Station with Type 1880 equipment to permit both chains to be controlled from a single remote Control Station situated at the dual slave station.

The dual Station, comprised of  the Purple Slave of the Northern Chain and the Green Slave of the Southern Chain, only used a single main antenna mast. This was  the first time that a dual slave with double tuned antenna had been built with Type 1880 equipment. It was also the first example of two chains being controlled from a single Control Station separate from the Master station of each.

The dual slave configuration was a late development in the system but proved itself in terms of cost savings. The station still only had one mast and coil house, but it was fed by two individual sets of transmitters, one for each chain that it served. The station control room would thus be equipped with two full sets of racks and transmitters. In the coil house, a  magic circuit of thyristors provided the tuning shift and circuit snubbing for this to take place. Doug Sim , spent a whole day in the coil house at  Stirling trying to make the first one of these units work.

The Swedish Decca story is told in a book titled  "Deccatiden i Sverige 1947-2000" by Lars Malmquist. Translated: 'The Deccatime in Sweden 1947-2000". Published by SMA, Norrköping, 3793-2000.

For a map of the North and South Bothnian chains, select this link.


The Skagerrak chain was opened on June 2, 1967.
Fjällbacka, Sweden Master 85.9000    kHz 58.517ºN, 11.300ºE
Jomfruland, Norway  Red 114.533   kHz 58.867ºN, 09.600ºE
Vallda, Sweden Green 128.8500 kHz 57.483ºN, 11.950ºE
Årjäng, Sweden Purple 71.5833   kHz 59.350ºN, 12.183ºE


The Southern Persian Gulf Chain 1C was based in three countries. Locations were:
Qarnain Island, United Arab Emirates Master 84.285   kHz 24º 56' 7"N, 52º50'59"E
Doha, Qatar Red 112.380 kHz 25º15'40"N, 51º33'54"E
Lavan Island,  Iran. Green 126.428 kHz 26º47'25"N, 53º13'00"E
Ras Zubayyah,  United Arab Emirates Purple 70.238   kHz. 24°20'N,      54°10'E 


Coverage was needed over virtually the whole of the Persian Gulf which meant that several States had to be involved. Usually these States were not agreeing with each other and often there were bitter rivalries and unhappy memories of past events. No one State could possibly be responsible for the whole of the Gulf.

Fortunately, Decca found a remarkably effective organization operating lighthouses and beacons in the area. It was the Persian Gulf Lighting Service at the time. It was operated by the major oil companies and so it was a "natural" starting point for Decca to introduce the system.

Decca initiated discussions with the PGLS and the major oil companies were deeply involved. Agreements were signed which led to a programme of construction and operation under the most difficult conditions but the end result was a reliable service. This continued until the military operations in the North required the relocation of some of the stations and ultimately their closure. The leading man in PGLS was Captain Webb and he was aided by representatives from Shell and BP and included the late Tom Gaskell, scientific adviser to the BP board.

It is believed that PGLS later changed their name to MENAS (Middle East Navigation Aids Service).  The two chains in the Persian Gulf were operated by MENAS. In June 1973, that organization announced the upgrade of the Decca chains to the Multipulse standard. Since the two chains were originally installed in 1960-1961,  the Multipulse system had been developed in order to provide extended lane identification ranges, particularly at night.

The existing Mk.V equipment at the seven transmitting stations was replaced with Mk.10 Multipulse equipment That also also permit users to take full advantage of the features provided in the new solid state Mk. 21 Decca receiver which started to see service in the merchant marine.

Work on the conversion programme, which included moving the Master station of the Southern chain a distance
of 12 miles from Das Island to Ouarnain Island, commenced on 1st March 1973 and was completed by year's end. The station was moved as the part of the development of an Liquid Natural Gas terminal on Das Island.

To ensure that the Decca transmitting antenna did not pose a hazard to the nearby air terminal while on Das Island, the standard 300 foot high transmission tower was instead, broken down into a three, shorter masts. This provided equivalent functionality and is the only known Decca chain which used such an arrangement. The South Persian Gulf chain was probably one of the few that had stations re-located due to unforeseen urban sprawl

On the new island,  the three Decca engineers were the only inhabitants. One day they were visited informally by Queen Elizabeth when the Royal yacht Britannia anchored offshore and the Royal family picnicked on the Decca island - a marvellous piece of true Decca folklore. To help break the boredom, each Decca engineer took turns at throwing a party for the other two.

The purple station was originally established on the beautiful beachfront corniche in Abu Dhabi but was moved in 1974 to Ras Zubayyah in order to facilitate hotel development.  Ras Zubayyah was no more than a piece of sand adjacent to the coast. Ras means inlet in Arabic. There was not a living soul for 50 miles around when the station was first built. The station did however, sport a nice swimming pool  back in 1978,  so a few expats would come over have beer occassionally.

Chain 4F, for the Straits of Hormuz, was proposed but never built due the political troubles in Iran after the fall of the Shah in 1979. One Decca manual indicated that the chain was under construction in 1987 but there is no proof of this.

A map of the Southern Persian Gulf chain and some photos can be seen here.


AMB Experimental Chain 5C (Multipulse)
Yorktown Heights, NY Master 85.0050   kHz
Yaphank, Long Island, NY Red 113.3400 kHz
Newton, NJ Green 127.5075 kHz
Red Hook, NY Purple 70.8375   kHz


On January 24, 1958, it was announced simultaneously in Washington and London that the Air Modernization Board (AMB) had signed a contract with the Decca Navigator Company's U.S. licencees , Bendix Pacific to provision an evaluation  Decca chain in the NYC area. The main purpose of the chain is evaluation with respect to helicopter operations.  New York Airways, who operate scheduled helicopter service from the Idlewild International Airport (now called JFK) to the Pan Am Building in the center of Manhattan.All aircraft will carry a Decca Flight Log

The AMD was formed under the chairmanship of General E.R. Quesada as one result of the Curtis Committee's Recommendations to President Eisenhower. Quesada stressed that "the Decca System has been choosen because it is the only one in a state or operational readiness". He also said that "the pictorial presentation which Decca provides will enable pilots to navigate with pin-point accuracy".

In another development, the United States Coast Guard experimented with the Decca chain in the New York City area. If provided coverage to the entrance and approaches to New York harbour and worked reliably out to 200 miles according to one user. An interesting comment is that during the New York operation there was a major electrical power failure and the City lost virtually all of its power and many of the emergency services were not available. However, the Decca stations with their advanced emergency power supply systems developed by Dougie Boycott continued without interruption.

There was also a chain set up in Georgia for the US Army at Huachuca. Ernie Easter of Decca was instrumental in setting up this chain. It is speculated that this chain was used to test the proposed application of Decca in Vietnam and may also have been used as a training system for aircrew since we know Decca was used in Vietnam.

California Chain (ID ?)

Decca Navigator Inc was incorporated in the State of California on 10/23/1963 under registration number 459735.  A contract to build an experimental type 820 chain near Los Angeles was signed in 1968. Evaluation commenced on June 8, 1970 as noted in Decca Navigator Magazine, August 1970. One of the big headaches for Decca was real estate and getting the masts to fit the sites.  Dan Arney, KN6DI, a former commercial pilot says that  "Los Angeles airport (LAX)  area had Decca coverage  for LA Airways. I was also out on  a fishing boat out of the Channel Islands near Ventura and it was fitted with Decca."

Wildomar  (approximate) Master ?
San Clemente Island Red ?
El Mirage (approximate)  Green ?
Ranchita / Hellhole Palms ( approximate) Purple ?
Information on  the New York City, New Orleans , California and Great Lakes chains can been seen here.


Phu Cat Master Central ? 14° 1' N          109° 2' E
Plei  Ku  Red Central  ? 14° 0' 11" N   108° 1' 17" E 
Cu Lao Re (Island)  Green Central ? 15.38 °N        109.12° E
Tuy Hoa Purple Central ? 13° 4' N         109° 17'E

Van Kiep, near Ba Ria (1) Master South ? 10° 30' N  107° 10'E 
Tây Ninh  Red South ? 11° 18' N  106° 5'  E
Phan Thiet Green  South ? 10° 55' N  108° 5'  E
Con Son (2) Purple South ?   8° 40'  N 106° 37' E


1) This was a small ARVN camp. It was about a mile east of Ba Ria, the provincial capital of Phuc Tuy province.
2) This island was formerly known as Paulo Condore and is situated in the South China Sea, south of Phu Vinh.

The Vietnam chains can be viewed here.


In the 1950's, the system steadily expanded in Europe with stations being built in France, Germany, Holland, Spain, Sweden, Finland and Norway together with added coverage in UK for Scotland and Ireland. This European expansion was helped tremendously by Bill O'Brien's Decca team making many brilliant improvements (such as crystalized receivers, Mk V and Multipulse formats) and the popularity of the receiver lease/maintenance arrangements. Decca was getting better and cost only £1.00 a day !

Figure 1 - EXPANSION: By 1957, Decca had expanded its European coverage as depicted in the above diagram.  The Swedish Chain became the North and South Bothnian Chains. The French chains shrunk considerably after this map was published. (Courtesy of Meccano Magazine, March 1957)


Additional References and Credits:

1) Bob Peters who worked worked 16 years on the Green Slave of 9B until the conversion in 1985 and for 10 years on both Dutch chains as a maintenance man.
2) Decca Navigator News: April 1972, April 1974, Sept 1976.
3) Decca Mk 19 Operating Instructions Manual, April 1971. Decca New Malden , Surrey, England
4) Information on the Spanish chains was provided by Santiago Insua Fernandez, email:  [hwasp (at)]whose father was a Decca maintainer and David Jones [e-mail:djones(at) ] who performed the system commissioning and antenna tuning at the master station of the southern chain .
5) Information on the Indian chains was obtained from Government of India,  Ministry of Shipping:
6) Hebridean and Bangladesh information provided by Doug Sim, e-mail: Doug.Sim (at)
7) Ireland info courtesy of Commissioners of Irish Lights web page
8) Orkney closure article courtesy of The Orcadian Times.
Excerpts from story: Signalling the End for Decca by Brian Flett
9) German chain 3F and Zeven info via web page:
10) Decca chain ID information obtained from Appendix AP-4  in PDF document .
11) Information for the Nigerian chain was obtained from the Sept 1976 edition of Decca Navigator News and the web page of
12)  Dan Dawson, a maintainer at the Alma, Nova Scotia station from the late 1970's until its closure in March 1982 provided the information about the Nova Scotia chain.
13) Data about the Japanese Decca Chains was provided by Tsutomu Arai, Director, Sena Co Ltd., Tokyo Japan.
Sena became a distributor of  Decca Navigator receivers in February 1966. http://
14)  The WUN Newsletter 1/1996 provided much general information about the chains which were still in operation in 1996. See . Editor: Ary Boender . e-mail: ary(at)
15) 89/113/EEC: Commission Decision of 21 December 1988 relating to a  proceeding under Articles 85 and 86 of the EEC Treaty
16) Many frequencies and co-ordinates (in decimal degrees)  referenced from NELS Interference Sources. Web site.
17) Norway information from:
18) Vietnam contributors:
      Christopher Rose: rosechristoph(at)
      Dennis Buley. e-mail: dbuley(at)
      Chuck Jackson.  email: cf.jackson(at)
      Keith Penman e-mail: pen325(at)
19) Excerpts from Wilfred St. John White's speech given at Church House, UK on Mar 30, 2000 added to various countries.
20) Refined info on Gulf of Finland, North and South Baltic and North and South Bothnian chains provided by Väinö
 Lehtoranta,    OH2LX  E-mail: vaiski(at)
21) Phil Jones recalled the station locations of the North Persian Gulf chain. E-mail:  phil(at)
22) Extracts from Decca's Genealogy provided courtesy Walter Blanchard, Royal Navigation Institute. <wb(at) >
23) Norwich (Red) info via Don Rayner. email: <donaldray(at)
24) Tony Tranfield contiibuted greatly on the French chain. e-mail: ATRANFIELD(at)
25) John Molloy-Vikers provided the initial information for the Australian chains and many other locations. E-mail: vickymv(at)
26) Australian station names provided by Roy Watkins, VK6XV E-mail: vk6xv(at) . Roy was OIC of the Decca Australia Navigator chains from 1972 through until 1984.
27) "After the system was shut down in the UK" information provided by Richard Caddy. e-mail: richard.caddy(at)
28) Bill Gaston <wgaston(at)>  and Christopher Rose <kitrose574(at)> provided the missing Bahamas sites. Also used web pages:
29) Pierre Painset  <pierre.painset(at)> web
30) "David G4FTC" <g4ftc(at)>
31) NYC info:  Diana Randle <dfrandle(at)>
32) John Beattie <johnbeattie1(at)>
33) Booklet: Decca and the Rome Control Area.
34) Decca Navigator News August 1970.
35) France - Extract from Télonde Newsletter
36) Bob Peters <peters-vdput(at)>
37) Decca Navigator News,  March 1952 - German chain officially opens
38) Decca Navigator News, Nov 1952. British South west story
39) Svenn Martinsen  <svennam(at)>
40) Erik Browaldh <erik.browaldh(at)> provided correction to Sweden 0A chain
41) USA California , Joe Consumer  <joeconsumer(at)>

Back to Intro PageOcr 229/18

MAy 2/22