in the United States

Drawing by Gerry Butler
If you have any feedback please contact me:

Email: Dr. Richard Walding (waldingr49@yahoo.com.au)
Research Fellow - School of  Science
Griffith University, Australia
Home Phone: 61 (0)7 32064976
69 Summit Street, Sheldon, Q, 4157, Australia

 


What are Indicator Loops?
 Submarines may be detected by many methods but one highly secret method of the past that relied on magnetic properties of submarines and surface vessels is the anti-submarine indicator loop. It relies on the production of an induced current in a stationery loop of wire when a magnet (in this case, a submarine) moves overhead. Even if wiped or degaussed, submarines still have sufficient magnetism to produce a small current in a loop. The technology was developed by the British Royal Navy in 1915. It was sent to various Commonwealth countries (Australia, Canada, New Zealand) for deployment. With the close technical co-operation between the Royal Navy and the US Navy, the indicator loop technology was enhanced for use in the US from about 1942 onwards. In the US, the control stations were known as 'loop receiving stations' and were a part of the Harbor Entrance Control Post (HECP). The first loop installation in the US was made at Cape Henry, Virginia in summer 1941. Units (loops, hydrophones, heralds) were installed in practically every major and medium continential US harbor in the few months after August 1942 and by the end of 1942 were being shipped to the South Pacific. Underwater detection was installed in major and medium ports along the east and west coast of the US, the Aleutians, South Pacific, Central Pacific, France, Philippines, the Canal Zone (Bahia de Panama), Australia and South America. At the time of surrender, several units were ready in California to be shipped to Japan.

Today, more than 50 years after the war, many of the countries that still have US Navy loop cables are having them removed for a variety of reasons. One is that many ports are expanding or having their harbors dredged deeper to accommodate today’s larger ships. The cables are an obstacle to dredging operations and a potential hazard for ships anchoring. The other reason is their enormous scrap value. Most of the cables were constructed of copper, but with copper in such short supply during the war years, some were actually made of silver with the intent of reclaiming them after the war. However, very little salvage was ever done. Consortiums of private investors and government officials are now being formed to locate and remove these cables. (One of the companies performing this service is Resolve Marine Group in Port Everglades, FL. Resolve has been providing a variety of marine services to companies and government agencies in the U.S., Central and South America, and throughout the Caribbean for the past 20 years).

The loop locations
 The following loop receiving stations (and their naval unit codes) were set up by the United States Navy. Links will take you to separate pages for some of the stations we have details for.
1st Naval District  
  • Casco Bay (Portland, Maine): 1A Bailey Island, 1B South Portland (Cape Elizabeth), 1F Peaks Island/Fort Williams
  • 1C North Scituate (Fourth Cliff to Provincetown, Massachusetts); and Rhode Island (Massachusetts)
  • 1D Nahant, East Point (Boston, Massachusetts)
  • 1E Gloucester, 25 mi N of Boston (Massachusetts)
  • 1G Portsmouth (Appledore Island, New Hampshire)
  • 1H Fort Burnside
  • 1I South Westport at Goosebury Neck (or Westport Point) - between Fort Rodman and US Naval Base at Newport (Massachusetts)
  • 1X Argentia - Naval Base (Newfoundland)
    		•
        3rd Naval District
    • Fort Tilden     New York Harbor Entrance Control Post (HECP)
  • Spermacetti Cove (New Jersey)

    •     4th Naval District

  • Fort Main Naval Station (Delaware)

    •     6th Naval District

  • Ocracoke     Naval Station (North Carolina)
        15th Naval District
  • Panama
    •    17th Naval District
  • Woody Island     Kodiak (Alaska)
    Cableship
  • USGC Pequot - a special page of photos detailing life aboard the indicator loop laying and repair cableship Pequot.

    LINKS TO RELATED PAGES:

     
  • Indicator Loops around the World (Home Page)
  • How an indicator loop works
  • Bribie Island (Australia) Indicator Loop Station (RAN)
  • Oban Bay, Scotland, Indicator Loop Station (RN)