CHAPTER VII
British salvage experts have performed extraordinary feats; the American Navy has produced divers excelling even our own; but it has been left to the Italians to accomplish the seemingly impossible. As a sheer feat of salvage, the raising of the Leonardo da Vinci remains unsurpassed.
The night of August 2, 1916, will long be remembered in Taranto, for just before midnight the whole town was awakened by a tremendous explosion. The people leapt from their beds and rushed towards the harbour, to find searchlights sweeping the bay and the finest battleship in the Italian Navy belching forth flames and smoke. The Leonardo da Vinci was doomed. In a moment 250 officers and men were wiped out of existence, and although the survivors fought most valiantly to quell the fire that enveloped the ship their efforts were vain.
Suddenly the decks of the battleship canted beneath them, shooting them like flies into the bay, and she swung right over and sank upside-down in 36 feet of water. The searchlights from the surrounding battleships lit up the darkness. Round and round they flashed, seeking the enemy who had dealt this mortal blow; but there was no sign of a periscope, nothing but the heads of the Italian sailors fighting for their lives in the sea.
A time bomb, secretly introduced into one of the magazines, had robbed the Allies of one of their most powerful battleships. This loss of a first-class ship of 24,000 tons, equipped with an armament of thirteen 12-inch guns, was a grave one to the Italian Navy, and the question of salving her at once arose. Famous foreign experts came on the scene, gazed on the visible portion of the keel of the ship which had cost £4,000,000, and shook their heads dubiously.
“Impossible!” they said. “The only thing to do is to blow her to pieces.”
The eyes of the Italians flashed. Somehow, at some time, they determined to salve the battleship. It might be impossible during the war, owing to the difficulty of getting material for the operations, but in their own minds the honour of Italy would never be satisfied until the ship which lay at the bottom of Taranto bay once more floated on the seas.
The sinking of the Leonardo da Vinci was, indeed, a great blow to the pride of the Italian Navy, and there was a general desire on the part of the nation to wipe out the stain and turn defeat into a triumph by refloating the ship. The more difficult the task, the greater the triumph; the more impossible it seemed to foreign experts, the more determined were the Italians to achieve it.
Throwing themselves heart and soul into the matter, the officers of the Italian Naval Engineering Corps studied the problem most carefully and formulated several schemes, among them a plan to build around the ship a floating dock which, when completely pumped out, would automatically lift the wreck. Shortage of steel and other materials at that time made this plan impracticable. Then General Ferrati, the chief of the Italian naval constructors, evolved a plan to raise the ship by means of compressed air and carry her upside-down to the dry dock at Taranto, where she could be prepared for righting.
It must never be forgotten that the battleship was upside-down, and that not only had she to be raised, but she also had to be righted. Rivet by rivet and plate by plate she had in the course of years been built up by hundreds of men into one of the strongest structures known. All the rivets and plates had been welded into a compact mass of 24,000 tons which now lay at the bottom of the sea. Afloat, she obeyed the hand and brain of man, would go wherever he desired; at his behest she turned to right or left, sped furiously through the sea or stopped. Now she was immovable as the mountains; to smash her to pieces would have been a gigantic task, costing months of time, tons of much-wanted explosives, and well over £100,000 in money. The queer thing is that Ferrati proposed to harness air to lift the sunken monster, just as though she were an airship instead of a battleship. In such ways do master-minds work.
So brilliantly conceived were Ferrati’s plans that orders were at once given to put them into execution. Divers went down to make a survey of the wreck, which was so rent by the explosion that a vast hole had been blown right through her from keel to top deck. A further survey indicated that the huge ship was literally digging her own grave. The weight of the upside-down battleship was all resting on the funnels and gun turrets, and these, owing to the enormous pressure from above, were piercing a way slowly but surely through the mud. Day by day the ship sank lower and lower, until the whole of her upper deck was completely buried and the greater part of her hull at the stern had disappeared. In six months the funnels cut down through a bed of mud over 30 feet thick before they encountered a bed of clay, which arrested the sinking of the ship.
No wonder the experts gave up hope. It really seemed that nothing but a miracle could bring the great vessel to the surface again. There she was, upside-down, buried deep in the clinging mud, an enormous, unwieldly mass that the biggest cranes ever invented were powerless to lift. It is a comparatively easy task to raise a weight of 10 tons from the seabed, but it is quite a different proposition to lift a mountain of metal weighing upwards of 20,000 tons.
In no wise discouraged by the difficulties of the problem, General Ferrati and his associate, Major Gianelli, ordered large-sized models of the ship to be built. These were accurately constructed down to the smallest detail, with miniature engines, propellers and guns; and every compartment was loaded to represent the things on board the battleship when she foundered.
A stranger might have laughed at the childishness of the Italian officers who were apparently playing with toy battleships. But things are not always what they seem. Actually these same officers were puzzling out the most abstruse problems, carrying out remarkable experiments which enabled them to determine how the ship should behave in certain circumstances. As a result were evolved some intricate calculations upon which depended the whole operation of raising the ship.
The small part of the keel still showing above the surface was used as a platform on which to build huts for the salvage workers. Other huts were erected, in due course, on platforms built up from the submerged keel. The assembling of the plant for the work was completed by the spring of 1917, when the people of Taranto began to observe the figures of divers about the wreck.
Those divers had no enviable time. They quickly discovered that the explosion had liberated a quantity of thick oil which clung to everything within the ship, and as they went down it obscured the glass of their helmets and rendered the men practically blind. As if the oil were not sufficient handicap, there were thick clouds of rust which fogged the water and added to the discomfort of the divers. Yet the oil, despite its drawbacks, proved something of a blessing, for it adhered to hundreds of shells and protected them so efficiently from the action of the sea that the Italians were able to use them after salving them!
The recovery of the ammunition was the first step to lightening the ship. Day after day shells were hoisted out of the wreck and loaded into lighters. It was dangerous work, but it became rather monotonous to those engaged in it. Monotony, as is well known, is apt to lead to carelessness, and carelessness in handling shells may lead to terrible results. It is a fine tribute to the carefulness of the men engaged on the work to know that they salved nearly a thousand 12-inch shells, three thousand 4·7-inch shells, some torpedoes, thousands of explosive charges and hundreds of tons of other ammunition without a single mishap.
Meanwhile, a cable was laid from the power station at Taranto right out to the wreck, a distance of a mile and a half; and with the power thus furnished the divers began drilling holes to take the rivets that were to hold the patches over the great rents in the hull. Slow and arduous work it was, and not without danger, for it cost one man his life. The patches were lowered into place, a layer of rubber was fitted betwixt the hull and the edges of the patches to make them watertight, then the patches were successfully bolted home.
More cables were carried out from the power station to work the air compressors, and, as soon as the divers had made a number of compartments watertight, the salvors began to pump air into the sunken vessel. The air which was pumped in naturally rose. It tried to get away to the surface, but the keel of the battleship, which had been most carefully repaired and made airtight, prevented it from escaping.
The air was thus caught, as it were, in a trap. There was no way out for it. It was not strong enough to break through the bottom of the ship, but it was strong enough to press down the water within. As the volume of air increased, the belt which it formed grew in depth until it had forced the water down for a distance of 26 feet below the level of the sea outside, and men were able to enter the bottom of the vessel through an air-lock, work in security in this belt of compressed air, and lighten the vessel by taking out her stores and coals.
By the beginning of November, 1917, the salvors occasionally felt the battleship stir slightly beneath their feet. Despite the fact that she was buried deeply in the mud, her bow was showing the slightest of inclinations to rise. The engineer in charge noted this with delight. Barely perceptible as was the movement, it was more than sufficient to encourage him to persevere.
Once more the thick oil cropped up to hamper operations and increase the many difficulties. As the water was forced down inside the vessel by the compressed air, the oil was deposited on everything. In most cases this did not matter much, but it was of far-reaching importance when it came to searching for leaks in the hull. The oil so obscured these places that it was extremely difficult to locate them, yet everything depended on their being discovered, for had they been left unstopped they might have let out the air and made it impossible to refloat the ship, or, alternatively, let in the water at a critical time and led to her sinking in such a position that she could never be floated again. Fortunately, the Italian salvage men were able to detect all the leaks and stop them effectively, as the sequel amply proved.
Critics of the operations pointed out that, should the salvors succeed in floating the battleship upside-down, there was not sufficient depth of water to allow her to be taken across that mile and a half of sea to dry dock. Even if they managed to get her to dry dock, all their work would be wasted, for the battleship floating upside-down would draw at least 50 feet of water, and the dry dock at Taranto was only 40 feet deep.
These difficulties were fully considered and plans made for overcoming them. As it was an impossibility to increase the depth of the dry dock, the only way to solve this problem was to decrease the depth of water that the battleship would draw. The engineer accordingly proposed to detach the funnels, gun-turrets and other top hamper from the deck of the vessel.
So firmly embedded were these things in the mud, that the feat of cutting them off appeared to be more than mortal man could accomplish. It was, too, pointed out that if divers tried to clear the mud away from round the funnels, to enable them to work at their task, the sea would quickly fill up the cavities again. Yet another aspect of the problem was that the mud pressing upwards against the deck of the battleship was preventing her from sinking deeper, and if the mud were removed the whole weight of the Leonardo da Vinci would once more rest on her funnels and turrets and drive them deeper still into the clay.
But the engineer, with a stroke of genius, made no attempt to clear away the mud at all. Instead, he tackled the job from inside the ship. Certain compartments were pumped out and used as air-locks, and in one turret the salvors succeeded, by the use of compressed air, in lowering the water to a level of 56 feet below the surface of the sea.
The men who performed the mighty task of detaching the turrets from the ship actually worked 20 feet below the level of the mud. All around them outside was 20 feet of thick black ooze, and above that the illimitable ocean; yet the air we breathe, properly compressed, held back the deadly waters and enabled the men to work in safety. No wonder the experts say we are only just beginning to discover the remarkable power of compressed air as an aid to salving ships!
Throughout 1918, some 150 men laboured about the ship to free her from her top hamper and masts. Despite all difficulties, the gun-turrets, funnels and other deck projections were detached from the ship and specially prepared so that when the vessel was raised they, too, could be brought to the surface. The open spaces in the deck left by funnels and turrets were covered in and made quite watertight, scores of tons of cork being packed into the Leonardo da Vinci to give her buoyancy.
Early in 1919 one or two tests showed that they could raise the monster when the time was ripe. But Major Gianelli, the engineer in charge, was taking no chances. To make quite sure of lifting her, he caused eight large pontoons to be fixed to her, each capable of sustaining a load of 350 tons, so in all he obtained from them the power to lift 2800 tons. These pontoons, or camels as they are sometimes called in salvage circles, are strong metal cylinders something like big boilers or tanks. They are of the utmost importance in salvage operations and figure in most wreck-raising work. All were filled with water and sunk into position exactly where their lifting power was most wanted. The divers lashed them with strong steel cables securely to the sides of the battleship, and by the month of June the work on the mammoth craft was all but complete.
Remained the problem of making it possible to tow her to dry dock. Notwithstanding that all projections had been cut away from her deck, she drew so great a depth of water that it was obvious she would foul the bottom before going any distance. To obviate this danger, the Italians set dredgers to work to cut a channel all the way from the wreck to the gates of the dry dock. The making of this channel, which was a mile and a half long, entailed the removal of thousands of tons of mud, but the salvors regarded this task as trivial compared with the work they had accomplished on the overturned ship.
Then the dock itself required to be specially prepared, for like all dry docks it was planned to take a vessel upright and not upside-down. The chocks down the centre of the dock, which normally support the keel of a docked vessel, were quite useless so far as the Leonardo da Vinci was concerned. So a forest of timber began to spring up in the dry dock. Mighty baulks of wood, 15 inches and more square, were built up from the bottom of the dock. These followed the outline of the ship so that the deck could be brought exactly over them and allowed to sink into place upon them. Other gigantic piles of timber were constructed to support particular parts of the deck.
By September 17, 1919, all these preparations were completed. The air compressors forced the water out of the pontoons and out of the hull. Certain compartments of the ship were filled with water in order to balance her evenly—and then the keel, with the great pontoons straining upwards, slowly arose out of the sea. For a time a stern battle went on between the mud which was gripping her and seeking to hold her down and the air which was striving to lift her to the surface. Then the air won. The battleship slipped from the grip of the mud, leaving her guns and turrets still embedded, and floated on the surface once more.
A rapid survey was made to see that she was fit for her journey, then the tugs took up their task and began to tow her slowly along the channel between the lines of buoys marking the passage. A stranger spectacle than the towing of this upside-down battleship was never before seen on the seas. The tugs managed to keep the capsized leviathan right in the centre of the channel, and by nightfall the vessel was at the entrance to the dry dock, and was skilfully manœuvred inside on the following day.
For two days she floated, held up by the compressed air within her hull, and during this time certain adjustments were made in the mighty timber frame that was to support her. The water was now drawn off from the dock and the Leonardo da Vinci settled down comfortably on her timber framework.
Her settling down placed a huge strain on the timbers, some having to bear the very great pressure of 225 tons to the square inch. The calculations, however, were so cleverly made, and the vast weight was so evenly distributed, that the framework supported her in perfect security. In itself this was a remarkable achievement. The slightest miscalculation, or one weak timber, might have brought about the collapse of the whole structure, and the battleship would have fallen, an absolute wreck, on the bed of the dry dock.
For months men swarmed about the upturned battleship, doing the final repairs that were necessary before she could be righted. The conclusive test of the Italians was nigh. Could they succeed in turning the great mass of metal the right way up again? No power known to man would suffice to right the vessel on land. Before the task could be attempted it was essential to place her once more in her element, the sea. On land she was immovable, on the sea she floated and could be more or less controlled by man, but whether man could perform the miracle of turning her right way up again, nobody knew.
The bottom of a ship, of course, has to be strongly built to withstand the pressures to which it is subjected. The deck, not having to stand the strain that the bottom is called upon to bear, need not be built so strongly. In this case the deck and the bottom had changed places, and it was therefore of the utmost importance that the deck should be strengthened to withstand the increased pressures that would arise in righting the ship.
Out in the bay the dredgers scooped a deep basin to enable her to turn over without fouling the seabed, and towards the end of January, 1921, the Leonardo da Vinci was towed to the place where it was proposed to right her. Four hundred tons of solid ballast had been loaded into her, and the engineers made preparations for pumping 7500 tons of water into certain compartments on her starboard side. Being above the centre of gravity, this weight would make her so top-heavy that she was bound to overbalance and thus turn right side up again.
There in the bay lay the still stricken leviathan. The valves were opened to allow the sea to enter her compartments, and the salvage men scrambled from the upturned keel and pulled away from her in their boats. The water began to flow in, and by the time some 800 tons had entered she began to turn ever so slowly. Soon, as the weight of water increased, she swung over with a rush, raising a big wave as the deck swept clear of the water. For a moment it looked as though she would swing right over and finish upside-down again. But the engineers had worked out their calculations to such a nicety that the battleship finally came to rest with a slight list, just as they had foreseen.
Across her deck, in big letters, was seen the motto of the famous Leonardo da Vinci: “Every wrong rights itself,” painted while the vessel was still upside-down in dry dock. It was a happy thought, and a pandemonium of cheering broke out as the legend came into view to tell of the most remarkable salvage feat ever accomplished.
The salving of the ship and her final righting took four and a half years. It was a Herculean task, and from first to last cost the Italian Government £135,000. Unhappily, General Ferrati, who conceived the brilliant plan, did not live to see it completed. He was succeeded as director of operations by General Faruffini, who in turn was succeeded by General Carpi, but during the whole time Major Gianelli was in charge of the work and to him is due the credit for carrying out from beginning to end, and bringing to a triumphant conclusion, the most wonderful salvage feat ever performed by man.