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Anti-submarine Indicator Loop stations in the United States
East Point Loop Receiving Station, Nahant, Massachusetts

Drawing by Gerry Butler (2000)

Loop Receiving Stations (LRS), as they were known, were operated by the United States Navy during WW2 as part of the harbor defenses largely against German submarines (U-Boats). This webpage is about the Indicator Loop Receiving Station operated by the United States Navy at East Point, Nahant, Massachusetts. Other nearby loop stations include North Scituate (Fourth Cliff to Provincetown, Massachusetts);  Appledore Island (Portsmouth, New Hampshire) and Peaks Island/Fort Williams Loop Station in Casco Bay (Portland, Maine).
 

If you worked at one of these, or at any other USNLRS, or have any feedback please contact me: Dr. Richard Walding (Email: 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

Introduction
From the outbreak of hostilities in Europe and the Middle East in September 1939, the US Navy had given some thought to harbor defenses. With the increasing likelihood that the US may become embroiled in the war work became more urgent.  In July 1941 - before the US entered the war - the Chief of Naval Operations recommended that indicator loops be installed as harbor defensive measures in al New England ports. Boston Harbor was to receive four indicator loops, 14 sono-radio-buoys, and 10 Army hydrophones. By October 1941 East Point (in Nahant) and Strawberry Point (In North Scituate) had been selected as loop control stations. Authorisation to establish the loop station at East Point was requested on 24th December 1941 and finally approved on 3rd January 1942 by Major General Thomas A. Terry, US Army.

Work began in late February but the contractor (for both sites) - Richard White and Sons of West Newton - was ordered to stop (on 22 April 1942) as the navy didn't have the permission from the army to build the structures. After an emergency meeting on 25th April, a modified plan was agreed to. Accommodation huts would not be built for the naval personnel and they would have to be transported form barracks at Fort Ruckman. Further, the loop hut (Naval Operations Building) was to be reduced from a 20' x 24' building to one of 14 foot square. However, the Administration and Power building was to be increased from 1' x 12' to 12' x 22' to provide standby barracks for two men.

Anti-submarine Indicator Loops
Indicator Loops are long lengths of armoured cable laid on the seafloor of harbors to detect enemy submarines. They were developed by the Royal Navy in the early 1900s and first trialled at the end of WW1. They were successfully deployed in WW2 in British ports and other Commonwealth countries such as Australia, Canada, New Zealand, South Africa, Kenya, Ceylon, Penang, and in allied harbours (Iceland, Holland, Dardanelles). By 1942 the United States had adapted this technology for its own needs and a dozen United States Navy "loop receiving stations" were established along the eastern seaboard of mainland USA particularly at the ports of Boston and Portland. The Pequot was the main cablelayer for the USN's indicator loop harbor defense. The deployment of indicator loops was highly secret and hardly any of the men on the ship knew the purpose of the cables; most thought they were underwater communications cables. The words indicator loop were not used - just cable. The sailors manning the loop huts were given rudimentary (3 week) training in harbor detection by indicator loops and sono-radio-buoys. To find out more about the role of the Pequot go to the USCG cableship Pequot webpage.

This diagram shows the arrangement of the cables in the loop ("3-legged") and the tail cable connecting them to the shore station. The Pequot crew laid the four loop cables at Boston in the correct position and joined it to the tail cable from East Point or Strawberry Point using waterproof splices and junction boxes.

Naval hydrographers were despatched to find a suitable location for the planned loops. The loops had to cross the shipping channels but could not be in water too deep as the sensitivity would be impaired. The Navy chose Lodge's Beach beside Bennett's Head at East Point for positioning the tail cables ashore. Note: Lodge's Beach was named after Henry Cabot Lodge (1850 – 1924) who owned a summer house nearby, and where Henry Cabot Lodge Jnr was born. It is commonly known as Dive Beach by the scientists at the Northeastern University Marine Science Centre on Nahant Road near to the beach.  The cableship Pequot laid all the cables and buried the two tail cables in a shallow trench all around the bluff area to the loop hut. The loop cables were laid in the traditional 3-legged pattern with leg spacing of about 200 yards. In the diagram below the loops are shown as a solid yellow line. However, they are really three parallel lengths of cable but it is too difficult to show at this scale. Loops 3 and 4, known respectively as Loop C ("Charlie" or "Cast") and Loop D ("Dog"). Loop 3 was 3 miles long with a 4.5 mile tail; Loop 4 was 4.5 mile loop but a short (500 yard) tail as it was close to shore. The cable was supplied by the Simplex Wire & Cable Co., Portsmouth. During World War II Simplex produced over 3000 miles of cable for the US Army Signals Corps communications as well as cable for harbor and coastal defence work.

Naval Operations Building
The photos below are of the "Naval Operations Building" [or Loop Receiving Station - LRS] at East Point which housed the indicator loop equipment, including the GE OS fluxmeter and paper chart recorder. The building is 14 foot square and 10 feet 3 inches high with one angular three-sided face. It faces east and entrance is through a door on the southern side. The small hole at the rear of the northern side was for a chimney. It was completed on June 20th 1942. All photos were taken by Dave Pierson, some in June 2000, and again in October 2008. The diagram below is taken from Gerry Butler's "Military Annals of Nahant, Massachusetts" 1996.

 

1. Sono-radio-buoy	9. Transmitter control box	21, 22. Resistance balance boxes
2. Fuse and switch box	11. Board	23. Telescope
3, 10, 15, 24. Chairs	12. Heater	25.  Cable entrance
4. Main switch	14. Radio transmitter	26. Binocular shelf
5, 13. Tables	16. Water cooler	27. Fire extinguisher
6. Communications system	17. Arms rack	28. Light switch
7. Sono-radio-buoy receiver	18. Cabinet	29. Inlet aperture
8. Radio receiver	19, 20. Fluxmeters (recorders below)	30. Flue and chimney stack

June 2000 - The naval operations building at East Point - taken from the path at the rear. The hut faces east. East Point more or less consists of angular rock ledge 10-15 feet above mean high water, with narrow, and rarely, wider 'crevices'.  Above this is another 10-ish foot rise, variously angled, variously grassy/brushy.  The 'top' is relatively level/grassy, the top is 'man made' as part of the defense installations.

June 2000 - A view of the southern side.

A view from the northeastern side. On a bench under the front window were the resistance balance boxes used to ensure the resistance of both halves of each loop was the same. Underneath them were the fluxmeters (galvanometer/amplifier).	Our intrepid photographer Dave Pierson - at East Point. Dave is a professional pyrotechnician.

Latest Photos
In October 2008, Dave Pierson took another set of photos (below). No further weathering seems to have taken place. Graffiti - well that's another thing!
 

2008 - the southern side	2008 - Leo Wanker has left his mark

 

2008 - the northeastern side. In the middle of the front window was the telescope. The window facing us had the arms rack underneath. Behind the window on the side was the water cooler and radio transmitter. The small hole to the far right was for the flue and chimney stack.	2008 - unsheathed cables, just to the north. Most likely 'dedicated ground', for signal integrity, and or lightning protection.

Lodge's Beach with Bennett's Head in the centre of the photo. To the left there is a trail that leads more or less out Bennett's Head, thence to level patch above Lodge's Beach.  This scene looks westish across the beach.	If you descend on to Lodge's Beach at the Eastern End and wander about you'll see a couple of oddities, notably, the concrete lump shown above; a bit under a meter, longest.  Might be a cap over/embedding tail cables.

This is indicator loop tail cable and  was found just to the SE on the track above Lodge's Beach. It consists of three insulated cables inside the usual sort of iron armor.	Trek along the top ledge to the Admin/power hut.  One puzzling observation is that there is no sign on the rocks, etc, of cables connecting the two.  The photo above shows what appears to be a power transformer embedded in and filled with gravel, insulator at 'top'. (Picture is 'straight down').  Remnants of power feed from rest of fortification.

The three rubber-insulated conductors of the loop tail cable are clearly visible in the rusted shroud of steel armor wire.	The coin helps envisage the size of the loop tail cable. It is a US 'quarter' (25 c) which has a diameter of 1" or 25 mm.

On along the ledge top above Lodge's Beach, there is one crevice with some remnants of gun positions tipped in, and in the next is the two brown ropy-looking armored cables (loop tails) about 12" apart, hanging in mid air as erosion has removed the soil. From a bit past here, the ledge top trail becomes eroded but you can scramble to the top, where public paved trail is. The cables are JUST barely visible from top, but out of line of sight.

If you walk along the top, public area to Loop Hut access you will see the scene above which shows the loop cable leading to 'access port' on top of ledge. The picture shows rock texture, is about 7' up, near vertical. Right hand area of 'access port' has broken end of 'another' cable, matching the two at the erosion site. There are 4 access holes cast into the hut wall.

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NAVAL ADMINISTRATION AND POWER BUILDING
The Naval Administration and Power Building is located about 240 feet to the southwest of the Operations Building and is set into the rocks of Cauldron Cliff. It has two rooms. On the southeastern side (to the left in the diagram below) is the power room with the door clearly visible. It contained the storage batteries, gasoline engine and alternator (110V at 12.5 to 15 kVA) as well as an oil furnace to heat the building. The other room - the administration room (on the right in the diagram) -  contained desks, cupboards, a refrigerator, stove, table etc. A doorway lead out to a walkway and then to steps at the rear.

Looking out of the Administration & Power Hut window over the war-time indicator loop field. The shipping channel into Boston is obvious.

The power room end of the building (closest to us) is on the southern side and is 12' wide (from L to R in the photo) and 7'8" deep. There were just the one window, a door and a concrete floor in this end.	The building measure 22' long by 14' wide and was 9'7" high. The upturned concrete slab is the remains of the 'head' - a toilet constructed outside the main building.

The rear of the building. Concrete steps, platforms and (originally) steel safety rails led from the bluff to a walkway that completely enclosed the station.	Looking north-east out to see over the loop field from the path at the top of the bluff.

Looking south-east over the loop field at a lobster fishing boat.	The administration room is at the northern end. It is 12' square with two windows and a wooden floor.

The power room. Ceiling battens show where the ply lining was attached.	The front wall of the building. The spalling of the concrete from the salt water spray is obvious.

The rear wall of the building. Note that the thin internal concrete wall has been demolished.	The hut back in June 2000. Graffiti is periodically removed.