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History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network

Memoirs of an STC Project Engineer - Part 4
by David Watson

Introduction: From 1967 to 1996 David Watson worked at STC, where he was involved with most of the large cable laying ships of that time. His function was that of Cable Loading Officer during the loading and Project Engineer whilst laying cable. Here David shares stories from his unpublished memoirs.

--Bill Burns

1973 - Autumn - CANTAT 2

Extracted from my memoirs for that period:- Autumn 1973

The previous loads and lays for CANTAT had gone without much to speak about.

But on CS Mercury in October of 1973, during Lay 5 I think it was, a Spanish steward from the Ship's Company suffered from acute appendicitis and although a very competent doctor was on board, he did not think it would be advisable to operate.

We were still some five or six hundred miles from Canada and therefore the Canadian Coast Guard were alerted and Mercury sailed at full speed towards the coast.

Normal speed for the Mercury on three engines was 13.5 knots but when the fourth engine was put into operation an extra knot or two could be achieved. This, incidentally, would run up the fuel comsumption from twenty-one tons a day at normal cruising speed to about twenty-five tons a day flat out, making it uneconomical to exceed 13.5 knots under normal circumstances.

Because of the nature of the emergency, Mercury proceeded at full speed to meet a helicopter from the Canadians and a few hours later, after refueling on an oilrig, it arrived in the middle of the night. Brave chaps these helicopter crews to hover over a vessel in the middle of an ocean with one of them dangling on a piece of wire to pick up a person on a stretcher. Needless to say the steward was rescued and made a complete recovery in a Canadian hospital.

And so back to Southampton and on the 9th November we started Load 6.

The loading of a Cable Ship started with the rigging of the vessel. This was performed by the Southampton riggers and normally took about twelve hours. The actual loading gangs would work in three shifts covering twenty-four hours a day, working twelve hours on and twelve off with a three day break after the sixth day.

The diagram shows how this was achieved:

  Day Night Day Night Day Night Day Night Day Night Day Night Day
On Watch A B A B A B A C A C A C B
Off Watch C C C C C C B B B B B B A
  Night Day Night Day Night Day Night Day Night Day Night Day Night
On Watch C B C B C B A B A B A B A
Off Watch A A A A A A C C C C C C C

The STC Greenwich Project loading officers worked twelve on twelve off for the duration of the load. Sometimes when you were on duty, the twelve hours on extended to fourteen plus if there was a problem. I can assure you very tiring, as after each cable end came on board and was loaded into the tank, one had to climb some thirty odd feet up and down a metal ladder attached to the side of the tank to inspect the stow. I was given to understand that CS Long Lines had elevators in the tanks. Easy life for some.

STC 1.47" (37.34mm) lightweight cable as used on CANTAT 2
The cable core has a four-part steel strength member at the centre surrounded by the copper conductor, then polythene insulation to the nominal diameter of 1.47" or 37.34mm. This is then fnished with a layer of aluminium and a polythene outer jacket.

STC lightweight cable profile

Detail showing the four-part steel core
surrounded by the copper conductor

Detail images courtesy of Cyril Malyon

After the first end of the cable was brought into the Centre Castle, (the undercover working deck of the ship) it was installed into the Power Feed Unit and the cable was then fed down into the tank in a bight. After this section of cable had been loaded, the cable end was brought out of the tank and positioned next to its repeater ready for jointing. See loading diagram below.

This sequence carried on to the end of the load, after which, once all the repeaters had been jointed in, the system was powered up and tested. A simple loading diagram is attached.

The complexity of systems like SAT 1 and CANTAT took a lot of thought by the Project team (when back in Greenwich prior to the loads) to design loading programs such that the ship as it was being loaded kept an even keel. Too much weight in one tank at the wrong time would put a lot of stress on the structure of the vessel.

Simplified Version of a Cable Loading Diagram

Back in 1962, the Marine Dept of SCL produced a document entitled “An Introduction to Cable Laying and Repairing “ and below is a copy of the chapter that relates to cable loading. The system that was used by STC Southampton was very similar, but because of the set up from factory to ship and also a very good bonus system, faster loading speeds were obtained. A top crew, when loading lightweight cable into a large tank, at times achieved speeds of seven knots. This was the same speed as a ship in a good sea state could manage.

CANTAT 2 route map, from a commemorative paperweight

Just prior to the end of Load 6 while working on the centre castle, someone from the dock side came on board, broke into my cabin and stole my wallet with some £200 of cash and travellers cheques. A lot of money in those days. I was not aware of this misfortune until a call went out over the Tannoy system asking me to go to see the purser and there a police constable met me. It transpired that somebody had found my wallet stuffed down the back of a toilet system ashore and handed it over to the dock side police. Luckily my driving licence had not been touched and the police traced me down by assuming that I was on the ship as Mercury was the nearest vessel to the toilets.

We sailed on the 21st November and the following day one of the Cable and Wireless officers came to my cabin with a packet of money. The officers and STC representatives had had a whip round during the previous evening and presented me with the proceeds.

This went a long way to easing my loss, and it was a very kind thought, but as it was my birthday I decided that I had to repay them in some way. We had a long transit in front of us with not a lot of work for us Reps to do so I held an open house cabin party. Officers coming off watch came in for a drink or two and then after a few hours the next watch would come in. This went on for a couple of days with me trying to get a bit of shuteye in between. It was one of the best birthday parties I had ever had.

The weather had not been all that bad during the transit and for the first part of the lay, but after a while we were hit by one all mighty storm. I had just started to get up out of my bunk to go on watch at about four in the morning when it happened. The ship was rolling to port as normal when one of these fifty-year waves, as they are sometimes called, hit the starboard side of Mercury and rolled her even more to port. I was forced to scramble up the side of the cabin bulkhead, now at an angle approaching forty-five degrees. It seemed like an eternity before she slowly righted herself, during which time I thought we were about to go under. After getting over the initial shock, I went down to the centre castle to find it was flooded and the ships crew frantically trying to sweep the water down into the cable tanks. Evidently when the wave hit it smashed through one of the portholes into the test room area and a couple of C&W officers who were sitting at a desk were washed out onto the centre castle, chairs and all. The damage to the starboard side of Mercury was horrendous. One of the companionways which was on the third deck had been washed away and the ship's side had huge dents in it.

I was speaking to one of the navigation officers after the event and he told me that if the ship had rolled a further two degrees we would have upended and gone under. With the weight of the cable on board I don’t think anyone would have had much chance to get off as she would have sunk straight to the bottom.

The weather and my pulse rate improved after a couple of hours and the storm came down from hurricane force twelve to about an eight and we were still laying cable.

The captain gave the STC personnel the option to cut and run or to carry on laying. The cable was at that time paying out over the stern at an angle to the ship of almost eighty degrees but was not in any danger of being damaged. Mercury was literally going sideways and forward at the same time. We decided that as we had come through the worst of it we would carry on. I think that the main reason for not stopping is that if we had cut the cable, we would have no chance of being home for Christmas.

Here is a picture of Mercury coming home up the English Channel with empty tanks and in a calm sea. This shows how far a ship can roll.

CS Mercury rolling at sea.
Image rotated to show the deck as level;
it is actually at an angle of 25° to the horizon!


Cable is coiled into a ship's tanks in a clockwise or right-handed manner, this being the natural coil that a conventional left-hand lay cable would take up; bends to the left in loading spans tending to disturb the lay of the cable.


There are two usual methods of coiling:

1. COILING "WITH LAY OUT" - This is the more usual method used in submarine communications cables. The coil is commenced at the outside of the tank and working inwards the turns are successively laid in until the tank cone is reached. The cable is then laid out to the outside of the tank in a direction approximately tangential to the cone at the point of completion of the last turn. Coiling is then resumed, working inwards towards the cone, where the lay out is again made to the tank side. Successive lay outs are sited in rotation to maintain an even height.

The advantages of coiling "with lay out" are - a reduced number of eye turns at one traverse of the tank (this reduces hazards at the cone, especially at higher speeds), the cable always being taken from the inside of the working flake.

2. COILING "IN AND OUT" - This method is more favoured for use with cables of large diameter. Having coiled in to the cone from the tank side, instead of laying out, coiling continues working from the cone to the outside of the tank and so on.

The advantages of "in and out" coiling are - less timber is required in the tank, the cable may be coiled into a smaller space, and chances of a foul-up at the eye are remote with large diameter cables and slower speeds of pay out.

This method of coiling is not generally recommended for armoured cable which is to be paid out at speeds greater than 3-knots. Considerable care must be taken when coiling the outward running flake to ensure that the coil remains circular, otherwise significant broken space will occur at the tank wall.


The ship's hauling gear should be sited on the foredeck so that there is a fair lead from the shore gantry to the top of the hauling gear sheave. If the distance from the shore gantry is more than a few feet it will be necessary to rig a loading span from such a gantry to above the hauling gear. This arrangement will depend on local circumstances.

From the hauling gear a line of hanging sheaves should be rigged to provide a cable lead in a smooth curve from the line of the hauling gear to the cable tank to be loaded. The spacing of sheaves will depend upon the type of cable to be loaded, heavier types usually require less sheaves for a given curve. This is due to the cable being less flexible and offering greater resistance to bending out of line and assuming non-conforming bends. Time spent in ensuring a smooth cable lead is usually time well spent and a fast loading rate should then be achieved without frequent stops for sheave adjustment. The sheaves should be so arranged that the cable line assumes a gentle slope between the hauling gear and the entry into the tank.

An alternative method of loading is to lead the cable over the bow sheaves using the cable engines. With preparations complete, the cable end is hauled through the loading line by means of a rope messenger already rove.

The cable end is then stowed in the tank pocket according to a previously prepared plan (i.e. a long end may be left up for a joint and splice to a subsequent end or a short end may be left up sufficient for connecting to a test lead or the end itself may be taken to the test room). Whichever is selected the end is secured in the tank pocket and the bight led down to the tank bottom. As cable is fed from the hauling gear the turns are coiled in a clockwise direction, each one a snug fit against its predecessor. Coiling continues inwards until the cone is reached and the cable is laid out to the tank side and so inwards again.

The position of each joint mark, mile mark and the number of the flake should be recorded in a tank book.

The end of a length of cable should terminate not less than the minimum bending diameter of the cable from the outside of the tank and thus it may be necessary to lay out the last but one flake before the cone is reached. This is known as short flaking and in this case wedge shaped pieces of timber are placed to fair in the two levels of cable. The decision when to "short flake" must be taken after study of the tank book. When a cable section is completed the top end is secured in a manner similar to the bottom end, care being taken that the cable Is not bent more than its minimum radius when stowing the final turn and positioning the end.

Thin battens of timber known as "thin wood" are placed under each flake of cable in the eye; this is to prevent the eye turns from dropping down between the coil and the tank cone.

At each lay out, the cable is protected by battens laid along the side of the cable. This protects the lay out from crushing by successive flakes of cable and these battens are termed "feather edge" and have one corner chamfered.

The cable is fed into the tank by the hauling gear operated by a gear man situated at the tank coaming. This man watches the rate of stowing by the coiling gang and adjusts the speed of delivery accordingly.

One man from the coiling gang, called the runner, stands at the tank centre and receives the cable from above, slides it through his hands as he runs round the tank feeding the cable radially out to the men at the perimeter of the coil. For an average size coil nine men would be needed at any one time on the coil. For sustained coiling two teams of nine men working turn and turn about are usual.

A bell or communication system between the pay out tank ashore and the gear man on board the ship should be available. A usual convention is:
      One ring - stop
      Two rings - go
      Three rings- go slow

Images and text copyright © 2011 David Watson

Read all of David Watson's memoirs:

Part 1: Laying SAT 1
Part 2: Sicily - Libya
Part 3: Germany - Sweden
Part 4: CANTAT 2
Part 5: ANZCAN

Last revised: 2 January, 2015

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