The wonders of salvage

A ship cast ashore always reminds me of a hospital ward and the men and women who are deprived by illness of the power to carry on the struggle of life. The ship, too, is a cripple, driven out of her element, unable to carry on the duties for which she was created, and this is why my curiosity in a case is always tinged with a little sadness. To the salvage expert, however, the beached ship is merely a problem, and his mind, like that of the physician, is wholly occupied in effecting a cure.

If straightforward towing will not get the ship off, he will try other means. He may set a gang of men digging a deep trench round the keel of the vessel at low tide, and as the tide rises the water, flowing into this trench, will give her just enough buoyancy under her keel to enable the tugs to do the rest. Or he may try a trick that was tried very effectively on one occasion during the war when a whole convoy of ships grounded during a fog. The salvage officer, when his tugs failed to shift them, set torpedo boats thrashing round at a high speed and the wash they created lifted the grounded ships sufficiently for the tugs to get them off. It was a simple, yet clever, solution to the problem.

But there may be factors in the case which make these methods useless, as happened when the s.s. Timbo was thrown ashore in Carnarvon Bay in 1921. She drifted at the mercy of a terrific gale, which was blowing dead on the shore. Lifeboats that put out to succour her were swamped by the enormous seas, and more than one brave man lost his life that stormy day before the Timbo, absolutely helpless, was driven right across the bay. Just when tide and tempest were at their height, she was caught up by a tremendous wave and thrown heavily ashore.

That tide happened to be exceptionally high, and when Mr. Henry Ensor came on the scene he found a strip of shingle just 100 feet wide separated her from the sea when the tide was at the full. There she lay, broadside on to the ocean, and over 30 yards beyond the reach of the largest comber that rolled up the beach. She was indeed out of her element, so much so that 30 yards or 30 miles would have made no difference to the average city-dweller, for to him the problem of getting her back would have been insuperable.

To tow her off on a beach like that was not to be thought of, for if tugs had been set to work they would merely have added to the difficulties. Directly they began to haul, the stony beach would have heaped up under the weight of the steamer, and the more they pulled, the deeper the wreck would have burrowed into the beach.

The first thing the salvage expert did was to put timbers under the bilges of the steamer to prop her upright and prevent her from falling on her side. Then, using lifting jacks, he gradually raised her and placed launchways beneath her keel to prevent her from burrowing into the shingle when the tugs started to pull her off. This work was completed just before the highest tide there was likely to be for some time, and rather than miss this tide the salvors started to get the steamer back into the sea in the dark.

Inch by inch they hauled that steamer across the intervening shingle until half the space was covered, until the seas lapped the launchways, splashed the keel. It was a tremendous fight. The tugs were hauling to their last pound. Slowly the launchways disappeared into the water and at last the salvors felt the Timbo tremble. Another long, strong pull and the steamer rose to the swell. Success had crowned the efforts of the salvage specialist.

Refloating the Timbo was a fine piece of work, just as was the raising of the steamship Fleswick with compressed air by the same expert, many years ago. But in raising the Silurus, Mr. Ensor accomplished a feat that ranks with the finest wreck-raising feats ever accomplished. The Silurus was a dredger, one of the most powerful ever constructed. Built for duty in the port of Bombay, she was completed about eighteen months after the outbreak of war. As it was considered far too risky to attempt to tow her out to India at that time, she was taken to the Gareloch, where enemy submarines were not likely to penetrate, and anchored until such days as peace returned.

She had been serenely sheltered in that haven on the Scottish coast for nearly a year, when dirty weather sprang up. In the ensuing gale, she dragged her anchors and was driven hard ashore. Had she remained upright, a tug might have remedied the matter in a simple fashion when the tide rose again. But unluckily she grounded on a very steep shore, which shelved away rapidly, and as the tide dropped she capsized and buried her funnel so deeply in the mud that she was all but upside-down. The top of the tower carrying the dredging buckets was thrust into the bottom of the Gareloch, and while the tower tended to pull her over, once she had overturned, it no doubt prevented her from finishing with her keel right in the air.

As in the cases of the Onward and the liner St. Paul, the problem was to right the ship before she could be pumped out and raised. But with the Silurus, the difficulties were increased by the top hamper, consisting of the tower with the dredging buckets.

Mr. Ensor, as unlike a miracle-worker as any one could imagine, went to the Gareloch and quietly looked over the sunken dredger. She was a big problem, but not too big for him to tackle. Moreover, he had the courage to back his ability with his own money. Calmly he offered to salve the vessel on the usual “no cure, no pay” principle. It meant risking quite a fortune, but this did not worry him.

Then he began to get out his plan for righting the vessel, the intricate calculations such a plan involves being not only amazing, but perfectly incomprehensible to the average man who is not possessed of engineering ability. He calculated on obtaining 1000 tons of lift by pumping compressed air into some of the compartments of the overturned vessel, and looked to pontoons attached to the tower and other parts of the structure to aid him in his plans. But, for the real work of pulling the ship over, he determined to rely on the power of steam-engines operating on the shore and hauling on a series of giant steel cables attached all along the ship.

The risk of pulling the ship to pieces in a job like this is so great that the novice would drag the ship apart far quicker and easier than he would drag it upright. If a cable were placed round the hull and a powerful steam-engine given full play ashore, that cable would crumple up the steel plates and gradually cut through them like a wire through a cheese, instead of moving the ship. These were the risks that had to be avoided.

Divers started to strengthen the ship with gigantic logs, 12 and 14 inches square, in order to withstand the terrific strain. A huge, strong frame of similar logs, protected by steel grooves, was fixed to the hull, to prevent the cables from cutting the ship to pieces.

It was slow work, for the salvors could only devote time to the wreck when there were no important war jobs to claim their attention. However, they managed to get in a day now and again, preparing for the great tug-of-war, upon which depended a fortune. Materials were not easy to obtain owing to the demand for munitions at the Front, so the salvors had to make shift with anything that would serve their purpose.

The divers, who set to work with hacksaws to cut holes through the steel plates for the passage of some of the cables, were greatly handicapped by the rust and mud, which made the water so cloudy that the work was difficult to see. Yet they stuck to their job and slowly, monotonously ate a way with their saws through the metal. Then they took up the task of preparing the seabed for the ship to come over on. She was practically lying on a submerged hill, and about a thousand yards of the seabed had to be removed to make a flat table on which the ship could rest in safety without slipping over again. All this took time as well as money.

Then it was necessary to find something ashore that would withstand the pull of the ship when the tug-of-war started, something that would be absolutely immovable while nearly 2000 tons was dragging on the ends of the hawsers. The salvage expert tackled this difficulty by getting four old boilers, sinking them into pits dug down to the rock, and filling them and the space about them with concrete, thus making them as solid as the rock on which they stood. These boilers were in this way turned into four bollards, each capable of resisting a pull of 200 tons. Then a propeller shaft, 12 inches in diameter, was cut into suitable lengths and from it eighteen more bollards were made and set hard in concrete, each bollard being capable of withstanding a pull of 100 tons. These were placed at various intervals on the shore opposite the wreck, and by the time they were ready the salvors began to juggle with some 10 miles of steel cable, from 6 inches up to 8½ inches in circumference, that had been specially made by Bullivant, whose cables have dragged many a ship back into her element while making a snug sum for the salvors.

If there is any special work to be done, any heavy weight to be lifted, the salvage expert the world over knows he is safe with Bullivant’s cable, that it will not break at the psychological moment and let him down. Some of these cables made of twisted strands of steel wire are 12 inches round—as thick as a man’s leg at the calf—and they will support without breaking a weight of 320 tons: 320 tons could dangle from this cable in the air and a man could stand under it in perfect safety.

The largest hempen ropes made for salvage work are up to 24 inches round, even 25 inches on occasion, so it can be imagined how difficult they are to handle. If 1 foot of a 25-inch rope were cut off, it would be more than most men could lift, for it would weigh 146 lb. A short length of 15 feet would weigh practically a ton. A rope of this size will withstand a pull of 125 tons, against the 320 tons of a 12-inch steel rope. It might be thought that a rope half the size would support half the weight, but a peculiarity about hempen ropes is that, while a rope of 4 inches will support 4 tons, if you treble the size of the rope to 12 inches you increase the breaking strain by more than sevenfold to 29 tons; double the size of the rope again to 24 inches and it will support just four times the weight of the 12-inch rope, or 115 tons. Similarly, the bigger the wire rope, the bigger the load it will take in proportion. Whereas a 4-inch steel cable will support 35 tons, an 8-inch cable will carry 150 tons, or nearly five times as much, while a 12-inch cable will support 320 tons, or nearly four times as much as the 6-inch cable, which takes 88 tons.

Few people know that such wonderful ropes exist, but the salvage expert has full knowledge of where to get them when he requires them, as he did in the case of the Silurus. The ropes were all fixed in place on the edge of the Gareloch, two batteries of boilers were set up to supply the power, but before they could be used it was necessary to arrange a series of signals owing to the fact that the boilers were out of sight of each other. For one lot to haul faster than the other would have been fatal. It was absolutely essential that each rope took its share of the load and that all were hauled on at the same time. As showing how carefully everything must be considered in so important a case, the salvors even worked out how much efficiency they would lose through friction when hauling on the ropes. They left nothing at all to chance.

Giant wire ropes were lashed round some of the top gear to prevent it breaking away when the ship came over, a big trench was cut for one set of ropes to work in, as only by cutting the trench was it possible here to get a direct pull on the ship, and at last the signal was given to haul away.

Slowly the Silurus came up, her funnel was tugged from beneath 10 feet of mud. The hauling went on until the pontoons were clear of the water, until they were no longer a help but a hindrance, so the salvors cut through the wire lashings with blowpipes and freed them from the ship. Adjustments were made and the next haul set the Silurus on a fairly even keel. Despite the strain to which she had been subjected, the salvor made all his calculations so carefully that she was not in the least damaged by the operations. Over £56,000 was spent by the salvor on these operations, but he won his tug-of-war with flying colours, and the award he received was the reward of sheer merit.

As already mentioned, the divers used hacksaws to cut holes in the hull under water. In other cases they may bring into play a range of pneumatic tools—hammers, chisels, and drills worked by compressed air, which is pumped through a pipe from a boat on the surface. The hammer and chisel will deliver hundreds of blows a minute, each blow doing an almost imperceptible amount of work, but the hundreds of blows tell in the end. An air-driven drill, in spite of the disadvantages of working under water, will cut a hole an inch in diameter through a plate or girder an inch thick in one minute.

Frequently, it is desired to remove some submerged rock which interferes with navigation, and for this purpose pneumatic drills are often brought into play to make the holes for the charges of dynamite. The diver proceeds by drilling a series of holes, inserting his cartridges, after which he stops up the top of the hole with a special stopping in order to drive the force of the explosion downward. Then he withdraws to the surface and the boat removes to a distance before the dynamite is exploded.

Sometimes, however, when it is desired to deepen a rocky channel, a powerful rock-cutter weighing several tons is brought into play. This tool is shaped like a pencil and the nose is fitted with a specially hardened cutter. It is raised to a height and allowed to drop upon the rock, which it gradually pulverizes and breaks up, the rock-dredger coming along and completing the work.

Another method followed in the deepening of the channel of the Clyde was to use diamond drills for boring the holes for the explosives. The famous Enderslie Rock which caused all the trouble was revealed one day about the middle of the nineteenth century through the keel of a steamer coming into contact with it. Up till that time nobody knew of its existence, but when this steamer damaged herself the authorities started investigations. They found a bed of rock just over 900 feet long by 320 feet wide, which menaced the bigger ships that were beginning to navigate the river. The only way of making shipping safe was to deepen the channel by removing the rock. Accordingly it was attacked by men working in a diving bell who began blasting it away with gunpowder. By 1869, after working on it for five years and spending £16,000, half the channel was deepened to 14 feet, the other half remaining at 8 feet.

Eleven years later the rock was again attacked, this time by diamond drills worked by steam-engines. Five years of continuous work saw the rock removed to a depth of 20 feet over the whole channel. This improvement, which entailed the blasting away of over 100,000 tons of rock, cost £70,000, so the Enderslie Rock, upon which the Clyde authorities spent in all a sum of £86,000, proved rather an expensive obstruction to find in the river. But it was no mean feat to remove it, as was done, without in any way interfering with the traffic.