David S. Jones, a former Decca employee, provides this very fitting introduction to the Decca Navigator system

"I have been struck by one fact that is perhaps unique to Decca amongst the hyperbolic systems featured in this web page. The fact is that Decca was proposed, developed, designed, promulgated, manufactured, sold-by, operated, maintained and supported by one company during its entire fifty year life.

All of the other systems were developed as part of a quasi-government research program and subsequently farmed out to various contractors for manufacture; leaving their deployment and support in the hands of some government department. Typically an armed forces agency or the like was tasked with system operation and staffing. Since these agencies just looked upon their task as budgetary administration, no continuous bond developed between the product and it’s keepers. Routine changes in personnel and re-assignment of government agency responsibilities would only serve to break any continuity bond. All of these agency staff would only consider their time spent with these systems as part of a routine assignment, however dedicated the individual. Hardware manufacturers would likewise have a similar transitory relationship with the system.

Not so with Decca, which maintained a closely bonded group of developers and engineers for many years, all of who played a part in the history of the system. Even Bill O’Brien, the systems founder stayed active in the company for almost forty years after he first joined. This common pool of knowledge, stories and pioneering spirit is something which I believe sets Decca apart when compared with others."


The difficulty of navigating a minesweeper across the English Channel and making a precise landfall at night was considered impossible without some form of precise radio navigation. Established on the south coast of England, Decca began transmitting on the day before the D-Day invasion force landed. Had this radio navigation aid not been available, it is now believed that D-Day would have followed a completely different plan. How did this all came about?

The Decca Navigator system found its origins in the United States but was later developed into an operational system by Decca Radio and Television Ltd. of London.  Originally it was conceived by an American, W (Bill). J. O'Brien as a method of measuring the ground speed of aircraft undergoing trials and was simply named  'Aircraft Position Indicator'. Without knowledge of the patents of Harms or Honore and without even being aware of developments in the US by Shanklin, Donnelly, and Holmes, O'Brien  worked on the system independently from 1936 to 1939. He was unsuccessful in raising any interest in the US Armed Forces or the civil authorities so the system lapsed until the outbreak of war in 1939. Thereupon he offered the idea to the British Air Ministry through his friend H. F. Schwarz, an American working in London for the Decca Record Company. Neither was aware of the work which was proceeding on pulsed navigation systems in Britain so the idea was rejected by Watson-Watt as being prone to jamming and subject to interference.

O'Brien and Schwarz, with support from Decca, then tested a prototype system in California using a master transmitter at 300 kHz and a slave at 600 kHz. Comparison was made at 1200 kHz and the accuracy of the system was demonstrated in a car. It proved the basic viability of the system and was a major departure from earlier proposals by using harmonically related radio frequencies for transmission. This solved the problems of identification and phase comparison at the lowest common multiple of the carrier waves without needing any sort of modulation. It was a neat solution and had the additional advantages of occupying a very narrow bandwidth  and only using low power for the transmissions.  It did not however, eliminate the problem of "ambiguity".

The British Admiralty, which started planning the eventual landings in France, had a requirement for an accurate navigational system so it started taking an interest in Decca in 1941. There was also a need for a stand-by navigational system to guard against any possibility of the existing "Gee" system being jammed hence further impetus was given to the development of Decca. Trials were organized off Anglesey in mid-1942 using the same frequencies and equipment that were used in California. This trial was highly successful and resulted in further research with assistance from the Admiralty Signals Establishment (ASE).

Early in March 1943, Decca was given the order to produce 27 receivers plus the driver and phase control units needed for the transmitters. All equipment was delivered by mid-May when the Royal Navy began its training and preparations in earnest. In January 1944, a test of Decca (or QM as it was then known) on new frequencies was carried out in the Irish Sea and it was also compared with the Royal Air Force Gee system for accuracy.

This is a position-line pattern for a guidance demonstration run to Chicken Rock on September 16, 1942. The inter-station base line was about 12.5 km (Decca Radio And Television Ltd, drawing 1942 from the collection of Walter Blanchard)
It is important to note that the Gee system was in widespread use at the time. The naval version of Gee (Outfit QH) was first used by the Royal Navy in the Dieppe raid in August 1942 and was subsequently established as a standard system for surface navigation. For Operation Neptune (D-Day), the initial legs of swept channels were planned to coincide with the same lines as the Gee lattice maps. So important was accuracy that some 860 invasion ships were outfitted with Gee Outfit QH.
decca_test chain_1944a.jpg
Station sites for the third Admiralty trial of the QM system. The base lines were approximately 45 nautical miles which comprised a true prototype for D-day. (From the collection of Walter Blanchard) 
Although Gee and Decca were similar in broad principles only, Decca was more accurate than Gee and in modern parlance,  more 'user-friendly' because the results were presented directly on clock dials called "decometers" instead of a cathode ray tube as was done in Gee. One disadvantage of the early Decca sets was the need for the decometers to be initially set up using an accurately known position. If there was a break in reception for any  reason, the decometers had to be recalibrated.

For Operation Neptune, four Decca transmitting stations were set up in great secrecy. Intense security surrounded the construction of the transmitters as knowledge of their location could betray the intended landing beaches. It was subsequently revealed that the master station, known as 'A', was built near Chichester. The western 'B' (Red) station  near Swanage in Dorset and 'C' (the Green slave) about a mile inland from Beachy Head. On the Isle of Sheppey, a transmitter was built to look like a 'decoy' in case the Germans discovered any part of the plan. After the war,  it became usual to establish a fourth (Purple) transmitter for additional accuracy, but it was not considered necessary for D-Day.

Signals from the Red and Green transmitters formed hyperbolic patterns. These were plotted on maps and were known as lines of lattice. The ladies responsible for calculating the Decca lattice lines worked in pairs in a hut at the ASE. So secret was their work that an armed guard was provided. Nineteen pre-production Decca receivers were made by the company on very short notice and these were fitted in the leaders of twelve minesweeping flotillas, five headquarters landing craft (LCH), and two navigational motor launches.

Transmissions from the chain commenced early on June 5.  Bill  O'Brien, Decca's developer, kept a prototype
receiver turned on in his London home. When the decometer dials came to life, he knew that the invasion was under way. There were also monitoring receivers set up on shore.

Perhaps because it was so secret, or perhaps because so few Decca sets were fitted compared with Gee, the use of Decca Navigator in Operation Neptune was not mentioned in any of the published accounts. Although the  system worked extremely well and provided more accuracy than Gee, it was less reliable due to a problem known as "lane slipping". Also, ships fitted with Gee receivers could only navigate accurately as far as the mid-channel mustering point.

During one of the Admiralty wartime trials, the test nearly ended in disaster. For ease of use, the ship performing the evaluation navigated on a single hyperbolic line which passed through a reef. Intent on only watching the decometers, they steered exactly on the line and nearly ran aground not thinking that Decca was so amazingly accurate!

Thanks largely to Gee and Decca, the 18th Minesweeping Flotilla, for  example, was only about four minutes late and 400 yards out of position on reaching the destination point off it's target beach despite strong winds and  tides during the passage. This was considered a reasonable margin of error! One of the navigating officers said afterwards " It was uncanny. It seemed as if we had some sort of overhead cable which not only showed us the direction but also our speed."

This is a sketch map showing the QM chain which supported Operation Neptune, otherwise known as D-Day.  The orientation of the position lines AB and AC on the French coast indicates the care taken to position the stations so that across-track accuracy was maximized on the channels to be swept. The circular rendezvous area 'Z' became known as Piccadily Circus.The dog-leg appearance of the swept channels  came as a result because the initial part was aligned with the GEE lattice system (AB) while the latter part was aligned with the Decca lattice (AC) (Drawing by Cdr H. St. A Malleson RN, Ret'd. From the collection of Walter Blanchard)
To the chagrin of the minesweepers, who could have made good use of it, the Decca chain was switched off on D-Day plus one, presumably because the system was so secret at the time. Some thought it was shut down due to transmitter troubles. Decca was never jammed and, as far as it can be ascertained, its existence during the war was never suspected by the Germans. It is now believed that the invasion would have followed a completely different plan with a potentially different outcome if it wasn't for Decca Navigator.


In 1945, the Decca Navigator Co, Ltd was formed and the first commercial chain of stations established in south-east England in 1946. The problems of ambiguity were never far away and a system of lane identification was introduced in 1947 which was still only a partial solution and did not completely resolve matters. It was not until the mid-1950's and the introduction of the ' Multipulse ' technique that reliable lane identification out to the same range as the basic pattern almost completely removed ambiguities.

decca_first_agreement_s.jpg This was first commercial hiring agreement for a Decca  MkIV Navigator dated 15 January 1947. The receiver was  fitted aboard the Steam Ship Carrickmines , ex City of Antwerp. Click to enlarge. (Photo by David Duncan)
In the 1960's, a very considerable effort was mounted by Decca to get it adopted by ICAO as the standard airborne navaid in preference to VOR/DME. It was a very serious initiative which even included setting up special chains in the USA at Decca's expense, but to no avail. Besides the considerable investment already made in VOR/DME, the technical problems of ambiguity and precipitation static interference, both worse for aircraft than for ships, counted against it, and there was also the fact that, with a reliable range of about 200 miles, a single Decca chain needing four transmitters covered little more area than a single VOR/DME installation. At that time, Decca was been installed on the British European Airways Viscount 701 fleet as well as on many smaller aircraft and helicopters and it was probably its zenith as an airborne navaid.

In 1975, Mr H. Schwarz, the Managing Director of Decca Navigator, admitted that Loran-C was probably a better aircraft navaid than Decca and that satellite navigation would be better than either.

Pulse-8 became Decca Survey's name for their short-range Loran-C system. It was designed for offshore survey and had a design range of only 300 miles although it got out much further than that. There were eight transmitters around the North Sea alone in the late 1970's and many others abroad.

Although Decca Navigator as an airborne system made little headway, many other devices produced by Decca were prophetic and well ahead of their time. The concept of area navigation (Harco), the airborne area-navigation computer (Onmitrac) and the flight-deck map display (Decca Flight Log) were all originated by Decca and have since become standard. Decca became very popular with pilots of helicopters and smaller business aircraft for getting into small airfields without other navaids. The system continued to expand and by 1989 had 42 fully operational chains around the world, including 42 master stations and 119 slave transmitters.

When the service first became commercially available, users would rent a receiver from the Decca Navigator company. In 1973, the factory near Raynes Park in South West London turned out one marine receiver every hour. By the early 1980s the widespread availability of low cost microprocessors made inexpensive Decca receivers available for purchase. The loss of rental revenue caused Racal Electronics, which by then had acquired Decca Navigator, to inform the Government that it could no longer afford to operate the system without financial support. From then onwards, the Decca Navigator Service was funded by the British General Lighthouse Authority (GLA) and Racal continued to operate it on the Authority's behalf.  In 1992 an agreement was signed between the GLA and Racal-Decca Marine Navigation Ltd that the 18 Decca stations that had not already been modernized would be updated to reduce operating costs. This multi-million pound investment was completed by Racal in June 1994 by which time the entire system had been fully automated. Large buildings filled with tube technology transmitter equipment built in the 1960's were replaced by automated solid state units housed in small transportable containers. A new Supercontrol centre was opened in Edinburgh from which the entire UK Decca system could be monitored. Staff numbers were reduced from 64 to 19 and running costs were reduced by 40 per cent.

Despite the system operating within its reduced budget and successfully maintaining Decca Navigator's 99.95 per cent performance reliability, the writing was on the wall for the service. The advent of GPS navigation satellites slowly made the service superfluous. During 1999, the GLA announced the final shutdown of the service at midnight March 31, 2000 following over 50 years of successful operation. The occasion was marked earlier that week by a farewell conference at Church House in London where users and pioneers of the system met to review the development of the technology and their experience of its benefits.

During its lifetime, the name Decca became a piece of nautical terminology that epitomized security and dependability. At its peak there were chains in all of the principal shipping areas of the world and an estimated 200,000 Decca users in Europe alone. By measuring the differences in signals received from transmitters along many of the world's coastlines, mariners and aviators were able to establish their positions with a degree of accuracy and consistency previously considered impossible. Even Concorde 002 was kept on track during its flight trials using Decca Navigator.

Speaking at the farewell conference, Stephen Clark, director for Racal-Tracs, said: "It is always sad when something good, that so many people had worked so hard to create, comes to an end. Decca Navigator was a huge success in its day but life moves on. Satellite positioning is with us now and happily Racal has not lost its lead. The company has built on its long experience to create the next generation of positioning technology." Continuing, Stephen Clark said:  "Racal was the first company to offer a commercial Differential GPS (DGPS) service and the rest of the world followed us.

Despite the free availability of GPS positioning, the withdrawal of the Decca service is still regretted by some sectors of the maritime industry. Most notably, fishermen valued Decca’s ability to guide them back to fishing spots at sea with a degree of precision that is only available now through the more advanced Differential GPS services. Other sectors of the maritime community regret the loss of a positioning service that is totally independent of satellites. The demise of Decca Navigator did not greatly affect the aeronautical community  because aircraft installations were less common than those of VOR/DME, the internationally accepted system for position finding.

Racal and Thomson-CSF also become Thales in 2000, thus loosing all ties to the recent association with the Decca Navigator system.

by Wilfred St. John White

The following tribute to the Decca Navigator system was delivered by retired Decca employee Wilfred St.John White at Church House, UK on Mar 30, 2000, the eve of the final Decca system closure. Users and pioneers of the system met here to review the development of the technology and their experiences of its benefits. Many thanks to Väinö Lehtoranta, OH2LX, who provided a copy of the transcript. Wilfred St John White sadly died 12 January 2006.

Church House,  March 30, 2000 - Everyone here is aware of the growth of the Decca Navigator System from the single chain operation in 1946 and its remarkable spread throughout the world. By the 1980's the coverage had extended so that there were chains in all Continents apart from South America and nearly all the world's major shipping routes were covered.

At its peak, there were over fifty chains in operation all of them working under international agreements which ensured reliable transmissions for all licenced users. To list the chains and give their dates of operation would be tedious. Suffice to say that for many years the average rate of coverage increase was one chain every eight months. This was quite an achievement when one remembers that the problems posed by every chain (or group of chains) were very different. I do not want this paper to be a lesson in history or geography. Instead, I wish it to be a review of our various successes and recall some of the problems encountered in spreading the system. Also, I want to pay tribute to some of the people involved.


Bill O'Brien sometimes spoke of the "bean-patch" experiment in which he set up two phase-locked transmitters in a field and received the signals on a two-wheeled handcart. As the cart was moved the receiver indicated the phase-change in the signals and so showed the presence of a hyperbolic pattern. I do not know the year but I believe it could be as early as 1937. Perhaps someone here knows the date better than I.

The story of Bill coming to the UK at the beginning of the war is too well known to repeat here. I will only say that without the genius of Bill and Harvey and Ted, we would never have had a Decca System. The first operational use of Decca was for the D-Day landings. The story goes that twenty receivers were required but only nineteen were available so it was necessary to take an experimental receiver from Bill O'Brien's flat in Dolphin Square to make up the numbers. The story may not be true but it is a good one.

The success of the D-Day chain lead to its relocation to the Scheldte estuary where it was used later in the war. These two operations clearly illustrated the practicality of the Decca system and led to its commercialization and the formation of The Decca Navigator Company. In passing the company was usually called "Decca", "DN" and sometimes ""DNCL" but Ted Lewis always stressed the full name should be used where possible including the capital T for "The".


I understand that in 1945 it was necessary to make a deal with the Government so that the system was established as the property of the company and that the company had the full commercial rights for the system's exploitation. I believe that £50,000 had to be paid by the company for it to receive these rights. Perhaps I am wrong here and it was £50,000 that the company was paid for its work during the D-Day Landings. I do not know which but I am sure the sum was £50,000. Even if we allow for inflation, it must have been a bargain whichever way the money went!

With the company under way (it was Decca Records in those days), decisions had to be taken regarding the system's development. It was here that the genius of Ted Lewis showed itself. These were days long before business was being widely done on a "provision of services"  basis.  Theidea of a company building transmitters and receiving payments from the hire (rental) of receivers was revolutionary then but looking back it is hard to see how the system could have progressed so well without this basic concept.

Not only was the idea revolutionary, its implementation was going to be difficult. Building transmitting stations just after the war was a formidable task but was only one of the problems. It was necessary to design and build new civilian receivers and an infrastructure for their maintenance had to be established. Charts had be available and there was a sales problem as hardly any one who knew what a radio navigation aid was. Despite it all, the first chain was built and receivers were available in less than a year. It was a tremendous achievement.


The English chain was sited to cover the Channel and parts of the North Sea. With its short base lines and high radiated power, it performed well and despite its lack of Lane Identification it provided an 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. Many of you here will recall the Decca yachts on the Thames which permitted so many enjoyable demonstrations of the system as well as the Decca aircraft flights which showed the fine characteristics of the system for aviation. These demonstrations were very effective in securing new hirings but for me, as a system promotion man, they were a perfect way to illustrate Decca's potential. I think that 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.


As the costs of providing the transmissions had to be borne entirely by the company, it was vital that we obtained as many marine hirings as possible. It was obvious that the greater the area covered, the more hirings would be obtained. With this in mind the Danish chain was built and operated by Decca with a subsidiary company in Copenhagen. It was our first overseas chain. The overall Decca coverage was roughly doubled. So too were many of our operating expenses. Although the number of hirings did not double, the significance of the overseas development was considerable, laying the ground for expansion in Europe.


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 team making many brilliant improvements (crystalized receivers, Mk V and Multipulse for example) and the popularity of the receiver lease/maintenance arrangements. Decca was getting better and cost only £1.00 a day !

Here I would like to mention Grahame Coles and his team who ran the various sales and service bases in the UK. Also the Commercial Office which, under George Hawker, Roy Mitchell and Dave Baker, co-ordinated the activities of all the overseas Marine agencies --- as well as many other things. A force persuading European countries to adopt Decca was much of the European coast line had been strewn with mines. There was a major requirement to clear these fields so that ports could operate properly. Exports were vital to nearly all European countries and this gave an added incentive.

Minesweeping and Hydrography go together and nearly always the various Hydrographic offices were great supporters. Not only did they help in getting the system adopted, they had great responsibilities for the chart preparation and distribution. Besides the Hydrographers, every time the system expanded there were many who were not Decca employees but were still dedicated to the system. These often came from the various Governmental Departments and from the Shipping operators who would be the users of the new coverage.

It is very difficult to make a list of the people who were so involved but I would like to mention some who were quite outstanding. In Holland, we had Mr Verstelle: there was Commodore Fogelberg of Sweden, Mr Rohrholt of Norway and finally Pierre Hugon of France. All of these men made significant contributions and it is a great pity that space and time do not permit my mentioning their many counterparts in other European countries. I should also mention the wonderful work done by the Decca agents and licensees. Again my list cannot be complete but I would like to include Captain Pripp in Denmark, Olle Wageus and Tor Palmquist of Sweden, Hvinden Haug of Norway, Jan Vollebregt and Caas Kooy in Holland, Drs Maillant and Pundt in Germany and Messrs Giroud and Laveriere in France. The list is far from complete and I apologize for the omissions. Most of my remarks on Europe have been related to marine matters but aviation was. important too. The Berlin air lift story is well known and there were the early air users like Silver City and BEA.


It was from India that the first non-European Decca chains were ordered. They were to provide coverage around Bombay and Calcutta and later on in the South. Our supporter was Mr Lahiri of the Indian Lights Authority. Local conditions meant that the building of these chains was difficult but the various problems were solved and the stations went on to provide useful additional coverage.


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

In the United States the first Decca chain was built and operated in the New York area. One of the users was New York Air, a helicopter company providing services from the airport to the Pan Am Building in the center of Manhattan.

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.


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

We initiated discussions with the PGLS and the major oil companies were deeply involved. Agreements were signed and led to a programme of construction and operation under the most difficult conditions but ended with us providing 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 was in the mid-fifties that I first visited Japan. We had hired a survey chain to Shell for use in Seria and I had to visit Singapore for discussions with their local office. Having got as far as Singapore it seemed a pity not to go "round the corner" to Hong Kong and then "a little further on" to Tokyo. With piston-engined aircraft a lot of flying hours were involved but it was time well spent.

Japan in those days was quite different from the present but it was obvious that for Decca it was a land of opportunity. Japan relies on the sea for its food supply and fishing is a major industry. There are almost no useful minerals so oil and steel have to be imported. The sea is vital to Japan. Furthermore, the Japanese people like new things.

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 I arrived, I found a few knowledgeable people anxious to learn more about Decca. They were not many but they were influential. The big names were Shimasue and Kiyono. I am happy to say Mr Kiyono is still very active in Japan and his company, SENA, is still hiring Decca-licenced Japanese-made receivers.

In the mid-50s, the basic problem for Japan was a shortage of money but as the country's financial situation improved so did our chances of success. In 1964 with Japan just beginning its up-turn we signed agreements with the Government and with a number of commercial organizations. These included Kobe Kogyo (now Fujitsu) as our 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. Despite the advent of Loran-C and GPS, two of the chains are still operating.


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. Five such chains were commissioned.

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. There were big responsibilities for the company and for David Baker who was deeply involved but the chains became an established part of Decca world coverage.


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 spent several months in the area and much was learnt. We kept good contact with all concerned in South Africa and this was rewarded by the building of five chains in the mid and late '60's. The chains were operated by a Decca subsidiary in South Africa and again represented an important step forward in the world's coverage.

I would like to mention just a few names in connection with this area. General Wilmott, the Supremo of the South African Forces and General Martin, the Head of the Air Force were closely involved whilst Colonel Broadhurst and an engineer called Wadley conducted the initial trials. It was Wadley who developed the communication receiver which established the technical base for much Racal Communications equipment. Another side story from South Africa is that it was then I met a gentleman called Ernie Harrison who became rather involved with Decca later on !


Australia had always taken a deep interest in the Decca system and, as part of our expansion campaign, we gave a number of presentations including a major symposium in Sydney organized by John Lucken. Our final opportunity came in a rather roundabout way. In the 60'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 and two chains were installed one in Dampier and the other in Port Hedland. Gerry Unkels of the Department of Shipping and Navigation was a tireless worker on these projects.


Hydrography and minesweeping are closely linked. The Royal Navy quickly saw the System's value for mine sweeping and survey. This was particularly true at high level. In this connection I would mention the Admirals Day, Nares, Ritchey and Irving and of course their successors. The influence of these people was enormous because of Britain's leading position in hydrography. The word quickly got around that besides its value for navigation Decca was good for position fixing. With this in mind in 1946 the company appointed Claude Powell as survey manager.
It was a significant step forward and gave a new way for the system to expand. In many countries, hydrography paved the way for the adoption of Decca for navigation.


It was clear there was an operational requirement (and hence a commercial opportunity) for small mobile chains. I well remember the day when  Sir Edward  Fennessy and his commercial manager, Johnnie Johnson, brought back the order from the Danish Government for a survey chain for use in Greenland.

The order was placed in summer of 1946 and in the following Spring the chain was operating in Denmark for initial tests. Later the same year it was shipped to Greenland and the survey programme started. In all, it was quite an achievement.

Demonstrations given in Copenhagen during the tests were attended by many and resulted in the Swedish Government buying their own survey chain the following year. After this, similar chains and chains operating in a two range mode became very popular for hydrography. Oil companies quickly recognized the assistance the system could provide to seismic and similar surveys. In 1949 the first oil survey chain was installed in the Persian Gulf by a Caltex subsidiary. Iain Thomson, who later became the Head of the Survey Company, was the Chain Commander. The year 1952 was the start of our "rent-a-chain" business with Shell operating in the Persian Gulf. It was the beginning of the rapid deployment of survey chains in many parts of the world and this continued until most of the activity was taken over by Hi-Fix. Military survey chains were used for mine sweeping with the French being particularly active with chains in Metropolitan France, Morocco and Tunisia. The fifties were an important time for survey development.


Besides the light weight transportable Decca chains for survey purposes the system has been widely used in a restricted user mode with large stations running long periods. These operations are not well known but were important. Broadly speaking, these operations related to the oil industry's long term large area exploration programmes and to military operations. They took place in many different areas but in general the ultimate users and customers were European or North American. Here are some examples.


For many years it was known that there were valuable reserves of oil under the North Sea. With the development of deep-sea drilling techniques it became practical to develop the area. Shell led this programme. The accuracies required for survey were too great for the navigational chains. To overcome this problem special Decca stations were built which provided baselines across the North Sea. Normally this would lead to unacceptable skywave interference but, as the exploration took place in daylight hours, no problems were experienced. There were two separate systems, Sea Shell and Sea Search and these provided basic position fixing for the initial surveys and rig locations. Decca has played an invaluable role in the North Sea oil development programme.


Perhaps because of the early competition between VOR/DME and Decca, it is often thought that the USA was not a big user of Decca. Far from it. In the mid-sixties two high power Mk V Decca chains were built for position fixing for oil companies operating in the Gulf of Mexico. They were particularly successful as they had greater range than the 2 MHz systems used previously.

Further South in the "Tongue of the Ocean" area the US government had built an impressive underwater research testing ground. Decca was the only system capable of providing the ranges and accuracies that were necessary to carry out the tests. It was a big project and lasted a long time. Decca both built and operated the stations.
Another area where Decca was adopted by the US government was" Vietnam during the war. A special Decca chain was built and was widely used by helicopters for the rescue of wounded troops. Again, a large and successful operation.


In the mid 1950's, The Decca Navigator Company of London, England, was run by Harvey Schwartz a real dynamo at marketing. The company was a subsidiary of the massive Decca complex controlled by Sir Edward Lewis. Schwartz's big success had been the utilization of the system in the D-Day landings. It was his dream to expand Navigator throughout the civilized world and in particular, to the United States.

Roy Mitchell, an ex-RAF squadron leader and an associate of Robert Watson-Watt, the British scientist credited with the development of radar had been selected to lead Decca into the North American market. He had already convinced the Bendix company to consider a North American licence. In the winter of 1956, Roy moved from London, England to Toronto, Ontario and established a Canadian office for Decca Navigator.

In 1957, the Canadian Coast Guard started to evaluate Decca Navigator for eventual certification as radio navigation aid for Canada. Chains were built in Newfoundland, Nova Scotia and Quebec for this purpose. Business was booming. Around Christmas 1958 when everything was going great, Roy Mitchell announced that Decca was about to withdraw from the North American market and the Bendix Corporation had taken over the licence. That meant the Decca Navigator division had to be moved to Ottawa because it would be managed under the wing of Computing Devices Canada (CDC), a Bendix subsidiary. Roy Mitchell was off to New York City to take over the Decca Radar Corporation there. By January 1959, the move to Ottawa had been completed but the transition was rocky one having encountered problems between senior management and staff. The basic issues focused around management's fundamental lack of understanding about marine sciences.

Within a short time, business was booming and CDC landed contracts with the Department of Transport, the Hydrographic Office and the Department of Mines and Technical Surveys. The company started conducting Decca Navigator tests with the Royal Canadian Navy and the United States Navy. The Canadian Navy adopted Decca and used it until Global Positioning System became the primary navigation system.  By 1961, the Canadian Coast Guard had completed the certification of the Canadian chains and they entered service. In the autumn of 1965, the Decca division was prospering, but the main business operations were somewhat less than profitable. Bendix, who owned 60 percent of the company decided to go public. It was a good deal for the stock brokers, but did absolutely nothing for the bottom line. Massive changes were needed but no one was fired. People were just moved around. Expenditures stayed the same and the income grew even smaller. There were also sorts of wonderful ideas and systems floating around in people's minds but without those defence contracts CDC's survival was in jeopardy. The most lucrative marketplace, the U.S. military was to be denied because of the "not invented here syndrome".

CDC eventually became part of the General Dynamics group. Today, the company is a  supplier of military electronics to both the Canadian Department of National Defence and to the United States. The last Decca chain in Canada having closed down in 1986, ended  Decca Navigator operations for CDC and signalled the end of an era.


The RAF were great users of Decca using the general navigational chains. However, they were also great users of Decca for special purposes. In Europe there was a special chain operated exclusively for the RAF. It was highly successful and ran for a long period. In the Pacific Decca was on Christmas Island where the RAF were responsible for the testing of Britain's first hydrogen bomb. A chain was built and performed well under unusual conditions. Later, there was a similar operation in Australia. The Christmas Island exercise was commanded by Air Vice Marshall Oulton and he pays tribute to the Decca involvement in his book, "A Christmas Cracker". Many people were concerned with the adoption of Decca by the Royal Air Force but I would particularly like to mention Group Captain Clare who is with us today.


Most things in life involve birth, development, adolescence, a prime period and then a falling off --- usually to make way for something new.   Navigational aids are no exception. Decca's expansion was continuous for over 35 years but in the 1980's changes were taking place. Furthermore, most of the major sea routes were already covered so now there were fewer areas for expansion.

More important, although major improvements in the system had taken place there were still fundamental limitations due to Skywave. Loran-C, although it had its own problems, could operate with longer base lines and so was adopted in certain areas. Similarly, there was the slowly evolving GPS system. GPS would take time but undoubtedly would be very attractive. However Decca's position was extremely strong. Decca had coverage in the important areas. It worked well and was backed up by a fine organization. Ironically, it was its very success that brought our  third problem --- some people wanted to "run their trains on our tracks".

It was a difficult period for us. With new technology it was possible to make receivers cheaply and these could be sold outright without the manufacturer having responsibility for the transmissions. Clearly, the time had come for radical change and we successfully brought in new licensing arrangements. However, eventually we concluded a contract with the Department of Shipping for them to pay for the running of the chains. This arrangement has worked well and the system has continued to develop but now the Agreement is about to end. Regrettably, the life of Decca is drawing to a close. It is clearly a sad time but we must remember the years of success


The answer to this question is quite simple. It was a very good system and it was brilliantly developed and managed.

Decca had well over a half century of full operational life which is much longer than practically any other radio navigational aid. Its success was mainly due to an exceptional number of quite exceptional people. To mention a few names, Bill O'Brien was a remarkable engineer combining inventive genius and an incredible ability to overcome day-to-day development problems. His friendship with Harvey Schwarz led to the system coming to U.K. where with the impending war there was a natural starting point.

Harvey was a giant of a man. He had a genial, pleasant personality and was able to quickly make friends and inspire loyalty and dedication in his colleagues. He had a natural quality for leadership and gained the respect of all he met. He was a man of vision and was quite tireless.

With Bill and Harvey together in London the system was almost bound to succeed under the genius of Sir Edward Lewis. Ted, as he will be remembered by many, provided the environment in which the system could grow, the Decca company. Ted also provided the political "clout" that was often needed and was able to obtain the money that was required all too often --- particularly in the early days. These three men are no longer with us but their memories will live on.

But it was not just three, there were many. When I joined the company early 1946, there was a lot of expertise already. On the technical side there were Donald Bridges, Denis Hendley and John Huggins and soon after John Vickers. Then from 60 Group we had Maurice Easy, Bill Sanderson, George Hawker and "Ham" Hamilton and from the Navy came Dudley Toller-Bond, Grahame Coles and David Baker. 1946 was a great year for Decca recruitment and I am mentioning only a few names.

And it was not just the outstanding skills of the people I have noted. We must add the dedication and hard work of thousands in the laboratories, the factories, the offices and at the myriad locations in the UK and overseas to get the full picture. It is not surprising the system did so well for so long with so much skill and willing effort available.

For myself, I joined in April '46 and left  in February  '91
--- forty five happy years.   Today I have only two regrets
--- there are so many people I have not mentioned and so many who are no longer with us.

Today we must all be proud to have been associated with the Decca Navigator System and with its phenomenal success. In closing, let me give some recommended reading --- Howard Capes house magazine, "Decca Navigator News", provides an excellent record of the system's life, particularly during the Golden Years. If you can get hold of some copies and are nostalgic, I recommend a big box of tissues !


In addition, these two informative papers on Decca Navigator are presented here:

Decca Navigator System for Ships and Aircraft Use by Claud Powell ,1958
Why Decca Works by Claud Powell , July 1967

Contributors and Credits:

1) Walter Blanchard <wb(at) >
2) David .C.Duncan , Aberdeen Scotland <dcdunc(at)>
3) Chris Lynn  <cdlynn(at)>

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May 5/21