CABLEMAKERS

Indicator Loops consisted of long lengths of cable laid on the sea floor to detect the passage of enemy submarines. This page has the details of some of the cables and the companies that made them. These are not the same cables as used for underwater (submarine)  telegraphy even though the cables may be similar.  For further information visit the home page shown below.

  Email: Dr. Richard Walding (waldingr49@yahoo.com.au)
  Research Fellow - School of Science
  Griffith University
  Home Phone: 61 07 32064976
  69 Summit Street, Sheldon, Q, 4157, Australia
Author with cables at Bribie Island

  • LINKS TO SOME OF MY RELATED PAGES:
  • Indicator Loops around the World (Home Page)
  • How an indicator loop works
    •
    CABLE TYPES

    SINGLE CORE LEAD LOADED CABLE - ADMIRALTY PATTERN 1989 (W. T. Henley's Telegraph Works Co. Ltd.)
    This is the cable that actually detected the crossings in WW2. It was made by W.T. Henley's Telegraph Works Company at Holborn Viaduct, London. No photos or samples are available anywhere in the world. It consists of a single core of 7 strands of 0.029" tinned copper wire laid up together and enclosed in three layers of india rubber wrapped in a layer of waterproof tape and wound with a serving of jute yarns. This is then covered with hessian tape and spirally wound with a soft lead alloy wire. The lead is covered with more waterproof tape, a tarred jute serving, two more layers of hessian tape, 22 galvanised steel armour wires (each about 2 mm diameter) covered in lead alloy. Then there is a braiding of dressed hemp yarn wrapped over hot pitch and resin, and finally a preservative coating. Final diameter (1.35") 33 mm. It weighed 6.09 tons per 2000 yard mile in air (6.8 lb per yard) and 4.56 tons per mile in sea water. Its breaking strain was 3.00 tons and had a resistance of 11 Ω per mile.  The cost in 1938 was UK£180 per 1000 yards. In some harbours the Royal Navy used ADM Pattern 13142, a 7-core lead-loaded cable. The electrical resistance was 6 ohms/km.
    Henley's also made another type of cable offered as a replacement for the Type 1989. It was Type 6190A - a lead covered single core of 28 strands or 0.012" tinned HD (hard drawn) cadmium copper wire. The cadmium increased the breaking strain from 25p lb to 470 lb.
    2 CORE CABLE (possibly ADM Patt. 841B)

    Left: 2 core, 7 strand, 0.029" cable as used in the HDA loops for sending out the signal. It was made by British cablemaker W T Henley (London) in 1940 and used in WW2.
    Right: Longitudinal section shows the two cores insulated with white centered black india-rubber wound in silk with jute beddings. This is wound with more silk and oiled jute insulation and 21 strand steel armour wire. A double layer of tarred hemp wound in opposite directions encloses the steel.

    3 CORE CABLE - ADMIRALTY PATTERN 5700

    Left: The 3 core, 7 strand, 0.029" was used for 110 V DC power. It was made by British cable maker Hoopers in 1940 (for WW2).
    Right: The 3 cores are insulated with 5 mm black rubber and printed with numerals 0, 1 and 2. Each is wrapped in cotton gauze and there is more cotton gauze around the three cores. Six strands of hemp beddings is used, followed by 12 strand armour and two layers of tarred jute braid (not shown in photo).
    4 CORE CABLE - ADMIRALTY PATTERN 7048 and 9610 (and Patt. 13139 & 13140)

    Left: The ADM Patt. 9610 was a 4 core, 7 strand, 0.029" cable used for loop tails. It was made by Johnson & Philips (UK) in 1941. It has a diameter of 25 mm.  This cable has greater endurance than Patt. 7048 (below) and was often used on the shore end of rocky landings.
    Right: The longitudinal section of Patt. 9610 shows the four central cores insulated with 5 mm diameter rubber (3 are white, one black), surrounded by 18 mm diameter rubber bedding. Also visible is the 25 mm wide cotton gauze around the rubber; the central square white rubber core (not visible) and the 22 strand steel armour. This cable was supplied by Johnson & Philips. You can just make out the reversed name transferred on to the white rubber (see photo below for a better image).


    Above: The Johnson and Phillips name is clearly visible on the cotton. Any attempt to move this fabric results in its destruction as it is made of single strands of cotton, not woven together.


    Above: The ADM Patt. 7048 Edison Swan cable. This is also a 4 core, 7 strand made by Edison Swan Cables Ltd, Lydbrook, Gloucestershire in 1940 for their parent company Siemens Electric Lamps and Supplies Ltd (38 Upper Thames Street, London). The details on the tape can still be seen quite clearly after all these years on the beach. This cable has 3 cores in white rubber and one in black rubber which are laid up together with centre divider of black rubber, square in section. The cores are insulated with a rubber sheath and armoured with 20 galvanised steel wires, finally braided with hemp yarns and compounded with preservative. Weight per mile in air: 3.1 tons. The Australian Naval Board paid UK£144 per 1000 yards for this type of cable in 1938.

    7 CORE CABLE - ADMIRALTY PATTERN 660

    Left: 7 core, 7 strand, 0.029" was used for 220 V DC power and for the HDA "Training" tails. It was made by Hoopers in 1941.
    Right: Longitudinal section. The 7 cores were each insulated with india-rubber and wound in silk and separated by jute beddings. This was wrapped in more silk and tarred jute braid and protected by 15 steel armour wires (30 mm diameter) and two layers of tarred hemp braid wound in opposite directions. Similar to Admiralty Pattern 13135.

     
    Left:     terminating lugs on a 2-core cable in the HDA Room. Right: the same cable showing how the steel armour wires were layed back over "pudding rings" (Adm Patt 1797) on the ends.


    Close-up of a 7-core cable armour wire and braid.  A hot pitch and resin mixture was applied by the cablemaker (in England) over the armour wires and then two layers of braid were wound on in opposite directions. A waterproof protective coating was added to the outside.

    FIRTH OF FORTH INDICATOR LOOP CABLE 1915
     This cable was manufactured by Liverpool Cables in 1914 and used for experiments by Prof. Alexander Crichton Mitchell at the Admiralty Research Station, Hawkcraig in 1915. The cable was recovered at the end of the war (1918) and given to Prof. Mitchell for his experiments on the variation in the vertical component of the earth's magnetic field when he was Director of the Eskdalemuir Magnetic Observatory in Southern Scotland. The cable was recovered in December 2005 by John Riddick using additional information supplied by Richard Walding and Peter Robinson; and Mitchell's article published in the Proceedings of the Royal Society of Edinburgh, viz: Mitchell, A C. On the vertical force changes during the "sudden commencement" of a magnetic storm. Proceedings of the Royal Society of Edinburgh Vol. 45, no. 26 (1925) pp. 297-301.

     
    Longitudinal view Cross Section

    “Liverpool Cable” used at Eskdalemuir: Four core, single strand 1.23 mm copper wire (#7) sheathed in 2-layer rubber insulation (#6) of diameter 3.7 mm and wrapped in jute identification tape (red, white, black and blue) (#5) with the manufacturer’s name “Liverpool Cable” printed on inside. The cores are separated with five strands of 36-thread cotton serving (#8), wrapped in two layers of linen identification tape (#4) and encased in a 1.5 mm thick lead sheath (#3) of diameter 12.8 mm and wrapped in 18 strands of tarred hemp serving (#2) and armoured with 26 strand 2.0 mm steel wire (#1) to a final diameter of 18.8 mm (¾").

    Linen identification tape (#4) The cores are separated with five strands of 36-thread cotton serving (#8)

     
    Toy showing Liverpool Cable reels. The Liverpool Electric Cable Company works was located in Linacre Lane, Bootle, Mersyside.

     

    Hoopers
         Hoopers was named after William Hooper, a chemist, who became interested in rubber about 1845.  He established a factory at Mitcham to manufacture rubber goods for the medical world, but at the same time was experimenting with rubber for electrical insulating.  He established a process for vulcanising electrical cables. In 1864 a consulting company proved his process was superior to gutta percha, and resulted in an 1865 contract with the Indian Government for a submarine communications cable 12 n. m. in length.  This cable, and an 1866 one to Ceylon were armoured by Henley's.  An 1869 cable to the Persian Gulf was again a Hoopers core with Henley armouring.  The passing years resulted in many more Hoopers cables.  In 1870 Hooper formed  Hooper's Telegraph Works Limited.  Probably their biggest cable contract was producing and laying the 2,300 n. m. cable connecting Vladivostock-Nagasaki-Shanghai-Hong Kong.  The C. S. Hooper when built in 1873 to lay the Brazilian cable, was the then second largest cableship in the world at 4,935 gross tons, second only to the Great Eastern.  Hooper was sold in 1881 to the India Rubber, Gutta Percha and Telegraph Works Company and renamed Silvertown.

    Henley
         W. T. Henley was born in 1814 at Midhurst, Sussex.  He was a worker on the London Docks in 1830 and self educated himself.  He established himself as a maker of scientific and electrical instruments.  One of his customers was Professor Wheatstone.  W.T. Henley cableworks began in a workshop in London, 1837, with the manufacture of covered wires.  Henley's first submarine cables were produced in 1857.  In 1859 he spent £8,000 building a factory at North Woolwich beside the Thames. His name would soon be synonymous with the development of submarine telegraph cables, a success story that culminated in 1863 with the laying of the Persian Gulf telegraph cable, 1615 miles long, for the Indian Government. By the end of 1873 the Henley site had spread to cover some 16 acres and Henley owned 3 cable laying ships and a 400 foot wharf to allow 500 ton ships to load and unload. In 1880 the original firm was reorganised as W. T. Henley's Telegraph Company.  He died in 1882.  In 1906 work was completed on the impressive Gravesend factory on the Thames, which like the North Woolwich factory included wharf facilities but, perhaps more impressively, extensive purpose built research laboratories. The choice of Gravesend for a site was an easy one, as company historian Ernest Slater wrote in 1937 "Gravesend is where the sea ends and the river begins". 

    The Second World War saw Henley's company winning praise for various tasks performed for King and Country, especially its contribution to 'Operation Pluto', the system of petrol pipe lines across the English Channel. The main Henley factory at North Woolwich however, suffered repeated damage during the war years which led to the decision to build a purpose-built factory at Birtley, completed in 1950.


    • Advertisement (left) and invoice for loop cable for the Australian Navy 31st August 1938

    Edison Swan Cables
         H.W. Smith & Co., established in 1910 as the Electric Wire & Cable Co. at the Trafalgar Works in the Forest of Dean, Gloucestershire, moved into new premises on the other side of Stowfield Road near the River Wye and adjacent to the then Steam Railway Junction in 1912, to be known as the Lydbrook Cable Works.  The Cable Works, during the first World War, 1914/18, employed some 650 people, producing cable for the field telephones, some 15,000 miles of it was made.  The factory was then acquired by the Edison Swan Electric Co. in the mid 1920s, then employing some 1200 people, producing Power Line Cables.  It closed down in 1965 with the loss of some 650 jobs.

    Siemens
         During these same Victorian years Sir William Siemens, who founded Siemens and Halske in1858, was equally as active in the manufacture of submarine cables, in addition to projects as diverse as dynamos and recording instruments. The Victorian Era came to a close and soon the Great War clutched Europe, acting as it ravaged as a great catalyst for technological and industrial change, particularly in the realms of electrical equipment and distribution. The great depression followed and during these bleak years The Edison Swan Electric Company became the founder member of the Associated Electrical Industries (AEI) in 1929.

    In 1953 AEI acquired Siemens Bros., taking over the Liverpool Electric Cables Company in 1958 and Henleys a year later. These cable companies were integrated as the AEI Cable Division, reorganised in 1960 into four product groups. In 1967 the General Electric Company took over AEI Cables and Hackbridge Cables Co., culminating in the formation of AEI Cables Ltd in 1968. In 1982 production of Mineral Insulated Cables commenced at AEI's Cables Bootle factory in Merseyside.



    Invoice for loop cable for the Australian Navy, 20th September 1938

    Merger
         Henley, Siemens and Edison Swan  eventually merged into one of the biggest cable manufacturing companies in the world.

    UNITED STATES NAVY CABLE
         The USN used two types of cable for indicator loops: Type 111 cables was used for the Legs and Type 113 was for the Tails.

    Type 111
    "Leg cable" consisted of a central conductor of 7 strand 0.040" 10AWG tinned copper insulated with 6/64" rubber compound. Covering this was a 0.012" thick rubber filled tape and a jacket of high gravity rubber compound. Another single layer of rubber filled tape (0.012") was next, followed by 28 strands of No. 12 BWG (0.109") armor wire. A waterproof outer serving of 16 strand 3 ply jute was used which was covered in coal tar. The total weight of the cable in air was 1421 lb per 1000 ft (897 lb in sea water). This cable had an over SG of 2.8 and was 1.218" in diameter. Its tensile strength was 13000 lb. A typical reel of cable contained 8000 ft, weighed 13, 700 lb and was 84" in diameter. The reel occupied a volume of 300 cu. ft.

     

    more to follow...