CABLE REPAIRS

Evening Post, Volume CXII, Issue 80, 1 October 1931, Page 14

CABLE REPAIRS

IN OCEAN DEPTHS

THE WORK OF THE IRIS

HAZARDOUS AND DIFFI-

CULT

To the average layman it might seem as if the proverbial search of a needle in a haystack would be more likely to succeed than grappling for a submarine cable half an inch in diameter, in water a mile and a half deep, and at a spot some 500 miles from land, right out in the restless Tasman Sea. But the cable-repair ship Iris, serene in the knowledge of her ability to accomplish her quest, has set out to find and repair the cable. It is known that the cable has developed a fault, which may at any time turn into a break, and that this fault is, approximately 500 miles from Wellington, and the job scheduled for the Iris is to grapple for and raise the cable, find the flaw, and repair it, so that the cable service between the Dominion and Australia shall not be dislocated. How long the work will take and what it will cost depends largely upon luck and the weather. It may last three weeks and cost as much as £10,000 to complete. On the other hand, it may take half as long and cost half as much. The cable which is to be sought for is one which* was laid in 1890, so it has had a pretty lengthy sojourn on the bod of the ocean. By this time it may have been shifted considerably from its original position by currents; earthquakes may have'affected it, too, and quite possibly it, is, in places at any rate, deeply covered by silt. Electrical instruments at the shore, end have located the approximate position of the fault, but the puzzle is for the Iris to find the cable, this strand lying on the ocean floor with water to the depth of a mile and a half above it. The way she sets about it/is this. She steams to a spot somewhere near the calculated position of tho fault and on the line of the cable route, but naturally this position finding can at sea be only approximate. A buoy is then anchored, and the Iris steams offou a, course at right angles to the direction, in which the cable runs. Having proceeded some five miles or so on this course, she turns about. The grapnels- are lowered overboard and the vessel .slowly retraces her course and continues on it to five miles beyond the anchored buoy, that is, if the cable has not been hooked. ■ By dragging her grapnels in this way on a course at right angles to the cable, the Iris, if she is lucky, may find what ,she is looking for at the first effort.' But she very,likely won't. The cable in the spot where the grapnels are dragged across it may bo so covered with silt that it remains undisturbed, and then the ten-mile journey is fruitless. In this case a move is made to a spot further' along the cable, .and the same process, is repeated. Sooner or later the cable will be hooked, and then begins the really anxious time for those in charge of operations on board. The cable having been hooked, the next step is to hoist it slowly arid carefully to the surface, which is no mean task when its. weight: and the depth of tho -water are considered. The strain is terrific Once the cable is brought to the surface of the water, it is cut in two. One end, with a large buoy attached, is returned to the sea, and the other is made fasfc on board the ship. It is at,this juncture that prayers-are offered for calm weather, for whether the work can proceed or: not depends largely upon having a relatively calm sea. Out i*i the Tasman, those on the Iris reckon they are.': lucky' if conditions are calm enough one day in three. . , . TINDING THE FAULT. It will be highly improbable, and an enormous stroke of good fortune, if the Iris happens to pick up the cable exactly at the point where the fault has developed: the fault may be a considerable number of miles on either side of the cut. So the next step is, working from the end made fast on board, to coil the cable on board, gradually, raising it from the sea bottom. In the cable tanks on board the Iris there is room, for 400 miles of deep-sea cable to bo coiled like -a gigantic garden hose, but it will not be necessary to draw up from the ocean depths more than a,few miles. Each'foot of the cable as it comes on board is carefully examined, and it may be that the fault is found and it may bo that it is not. : '■ ."-■•■ - ' '.■•■■■•' If not, the laboriously coiled length is gradually returned again to the sea, and its end marked with a buoy. The other end previously marked by a buoy is now taken in hand and some miles, of cable, if necessary, gradually drawn on board. By, simple logic,,it is obvious that the fault must be located in this part of' the cable as it was not found in the other part.' Once the fault is located, a piece of the cable containing it is cut out and a new segment •puced in. For this purpose the Iris. carries on board 40 miles of new deep-sea'cable, but that is probably a great deal more than it will be* necessary to use. She i« not a cable-laying ship, only a'cable-repairing one. When the new segment of cable is spliced in, the whole previous process is reversed. The cable is carefully paid out until the cut end is reached. That is spliced to the other end, the position of which wae previously marked with the buoy,- and the mended cable is ready to be' returned to- the _ocean depths whence it came. When it has been carefully lowered into'- place again, the work of the Iris will be done. A TICKLISH JOB. 9 The whole operation, especially frosi the time when the cable is brought on board, is a very ticklish business, calling for infinite patience : and perhaps for instantaneous decision. At any time with the onset of rough weather it may be. necessary to cut and abandon the cable temporarily, for neither the Iris nor any other, vessel can heave about in a rough sea with the deadweight of miles of cable hanging over her side. If the cable must be cut, its end is marked with a buoy, of course, so that when the weather moderates it can easily be located again. Such work as that carried out by the Iris 'calls for highly skilled labour, and seems more suited to.the British temperament than to that of other races. Other, countries possess cablerepair ships, but nearly all the world's cable-repair work is done by British' ships and men. Amongst these the Iris and her officers and men are recognised as experts. How they get on with their present job we shall hear through curt and unromantic wireless messages, which in their formality and terseness will tell nothing of the hazards and incidents of the repair to the damaged cable.