The first air-lock made by Cox was crude but satisfactory, then others were constructed. The tubes were made from disused steel boilers six feet in diameter and 12 feet in height. They were built in sections but taken out to the wreck in one piece in order to reduce diving work in deep water to a minimum. Steel ladders were fixed to them inside and out. Then the lock was positioned, bolted down and tightly sealed. Great care had to be taken in placing the air-locks to avoid frames and stiffeners in the ship’s hull. Within this diameter of six feet, a man had to use an oxyacetylene burner to cut an opening in the ship’s bottom. As it was possible that problems would be encountered, McKenzie went down in the lock with the first man to begin cutting. The experience was unpleasant, for when the vessel had turned over, fuel oil and liquid in the bilges had poured over everything, and the intense heat caused foul, choking fumes to rush into the airlock from the ship’s burnt red lead, oil, paint and bilge-water. The two men hastily scrambled out and soon recovered in the fresh air.
The first air-lock was fixed in the forward boiler room near the forward bulkhead. After a second lock was fitted, men could work inside the hull without discomfort from bad weather whilst the ship was without buoyancy on the sea bottom. Hundreds of small leaks had to be sealed in the hull. Compressed air in the compartment helped to hold in place anything put in a hole, so sealing was easier than was the case with Hindenburg. Work was discontinued if violent weather prevented the men from passing between ship and shore. Even under the best conditions the difficulties were immense of fitting a tall air-lock swinging from a crane to a steeply-sloping keel under water in a current.
Inside the hull divers found an indescribable tangle of machinery, piping and everything which had fallen loose when Moltke had turned turtle. Much of the metal was corroded, and everything was plastered thickly with mud mixed with coal-dust and oil. The divers had submersible electric lamps and telephones, but there was always the risk of short circuits, apart from the constant danger of air-pipes being cut by jagged metal. For safety they worked in pairs. Working conditions were often appalling but at last, by teams working above and below the water-line, they had three watertight compartments inside the ship – at bow, stern and amidships. Manholes were then cut through the bulkheads separating the various compartments, and electric cables run through them so that lights could be installed to work by.
McKenzie described the vast amount of work which had to be done before a ship was ready for lifting: all pipes between half an inch and 18 inches in diameter had to be cut through on both sides of the bulkhead and plugged with specially made soft wood plugs. The plugs, set in red lead putty were driven home, and if over three inches in diameter shored to a convenient point. Cement patches for all compartments, which were as large as 20 feet by 16 feet, for boiler rooms etc, were held in place by shutters and toggle bars and the edges sealed with oakum or tallow. The rubber sealing strips had perished on many watertight doors, and the doors themselves had buckled badly under the rush of water as the ships capsized. These doors had to be forced open and relined with oakum, felt or spunyarn soaked in red lead. Sills had to be cleaned and dressed up with a file to remove high spots, and the doors then closed and strongbacked. Badly buckled doors had to be removed, and the resulting apertures shuttered and concreted, or fitted and caulked with stout wooden patches faced with pudding joints. These, too, had to be built. Then stages had to be fitted in stokeholds and bunker spaces to provide access to doors which had to be closed, the ships being upside down, of course, and the doors up to 20 feet above the nearest deck. The many compartments could not be reached by the normal means of access, so it became necessary to drill through armour plate up to three inches thick and through hundreds of panels, and to fit new ladders before the work of reclamation could proceed. When all the transverse bulkheads had been sealed effectively, the longitudinal armour bulkhead forming the bunker wall on each side had to be treated similarly, so that control could be exercised over the list of the ship before it could be raised. After bulkheads had been sealed to a low level, great care had to be taken in case the ship rose prematurely; not more than two compartments were allowed to be pressed down at any one time, other compartments were exhausted and the water level was allowed to rise to maintain negative buoyancy. A.S. Thomson, who had watched the scuttling of the fleet from the top of a hill near Lyness, was in charge of this part of the work. In recalling these days, he said that no special working clothing was worn, and that the worst part of the work was when one emerged from the top of an air-lock in wintry weather and had to descend the pitching lock in biting wind.
McKenzie was in charge of the team scaling the side-tanks inside the ship. There was a scare when air began to vaporise, an indication that pressure was being released and that water would rise inside the hull. McKenzie immediately ordered a stoppage of work and instructed the men to get out. To do so, some had to climb back through four manholes in the bulkheads, feeling their way in darkness as the lights failed, until they reached the air-lock entrance with the escaping air at gale force blowing their jackets over their heads. But it proved to be only air rushing into the forward end of the ship which was rising, the cause being the closing of a valve by a man who had misunderstood an order.
By May 1927 the ship was watertight and all sections could be inflated independently or together. It was a noisy, animated scene with the throb of compressors on the tug, and Moltke surrounded with rubber pipes of all descriptions which squirmed in the movement of the water like monstrous sea-snakes, while a maze of electric cables supplied the plant installed inside her. Before the lift took place, the main sections were charged to bring the ship within about 1,000 tons of the established figure for positive buoyancy. Pressure was first applied to the low side bunkers until the list began to decrease, and then to the high side bunker space until pressures on opposite sides were equal just before the inclinometers registered zero. Pressure was then increased in all sections as required. Lifts were invariably timed to take place at lower water. Maximum advantage was thus obtained from the lower head of water outside the ship, and therefore there was a greater displacement of water inside.
But whether Moltke rose by bow or stern she had a steep list. A destroyer and a pontoon were therefore grappled to the starboard side and sunk to keep her down, and the two biggest docks were brought along the port side. The diving team then took down 20 nine-inch cables and shackled the ends to gun turrets. At low tide the cables were winched on the docks until they were taut. The combined force of the rising tide, mechanical lift and compressed air raised the ship, but not only was she still listing, but one of the nine-inch cables parted, followed by a series of explosive sounds as others broke loose in a chain reaction. The operation was stopped, Moltke was again lowered to the bottom, and divers went down to investigate. They reported that the cables, though taking the load, had been severed by the sharp edges of the deck. Metal pads were therefore made for them to pass over, new cables laid and a thorough cheek made of the hull inside and out.
All air-locks were fitted with specially tested pressure gauges with 14-inch dials, so that the pressure in each section could be read to the nearest quarter of a pound. Men equipped with lifebelts were posted at the top of each airlock to record the pressures on slates. The slates were held up, the figures on them read through binoculars by salvage officers on the tugs, and instructions shouted back through megaphones so that inlet and exhaust valves could be manipulated as required. The large exhaust valves on the top of each air-lock enabled pressures to be balanced and buoyancy to be kept negative until all was ready for the final lift.
As buoyancy increased in the forward section, and as the suction grip of the superstructure embedded in the mud was broken, there was a slight upward movement of about two feet a minute. Then the driving force of expanding air shot Moltke to the surface as a million and a half cubic feet of surplus air was expended in a few seconds, sending waterspouts soaring upwards. She still had a list, but it decr
eased to only two degrees as the hull climbed 20 feet above the water. The men on the airlocks had to hold on tightly until stability was obtained, and one of them commented ruefully, ‘I don’t know about lifebelts. It’s flaming parachutes we want up here.’
A workman in a boat made fast the painter to the Moltke and was about to enter an air-lock as the ship rose. Feeling an upward movement, he glanced down and was surprised to see his little boat hanging down vertically by the painter. Tugs were quickly positioned and made fast, and the great chains anchoring Moltke to the docks were buoyed and cast off. During the nine months’ work in Moltke, 30 men worked eight hours a day inside the ship with air pressures ranging from 15 to 22 pounds, and six divers worked six hours a day at a maximum pressure of 35 pounds.
When a ship was raised and secure, there was, of course, no further need for the great air-locks. They were therefore removed on the quayside and kept for use on other wrecks, small air-locks ten feet in height being fitted in their place for the tow.
Cox sought and obtained Admiralty permission to put Moltke upside down in their dock at Rosyth. (Leonardo da Vinci had been towed in this way, but only across Taranto harbour.) Then he had to find £8,000 insurance upon two-thirds of the ship’s value and carry the remaining one-third himself. He had also to sign Moltke over to the Admiralty as security against any possible damage to the dock at Rosyth.
On 16 June the tow began to Lyness pier. While still between the two docks she suddenly stopped and the tow-line parted. Tugs failed to move her. Divers went down and found that one of the huge 11-inch guns had dropped forward with its muzzle thrust into the sea bed where it became more deeply embedded with every new effort to drag the ship forward. Next day the gun was blasted free. Six new lifting wires were passed under the hull and tightened up at low water, and as she rose with the next tide she floated seven feet higher than before and was beached successfully near Lyness pier with her upper surface 20 feet above low tide level.
Next morning Cox sent a gang to work on Seydlitz. Simultaneously machinery was removed from Moltke which was prepared for the tow to Rosyth. This part of the work, too, was also marked by ingenuity. Moltke’s bottom, now high and dry in all tides, became a railway siding as the pier railway was taken up and relaid on the upturned hull. Six-foot square openings were cut over the engine and boiler rooms where the air-locks had been. A light engine towed a three-ton crane along the railway lines. Down below everything worth moving was cut up with oxy-acetylene burners into pieces which could be passed through the holes. The crane lifted out 3,000 tons of metal. Dock sections were moored alongside, and on them, ten-ton cranes with extending jibs swung the metal ashore. Moltke’s main components were: 1,700 tons of steel and wrought – and cast-iron scrap, 200 tons of armour and 312 tons of non-ferrous metals which included copper, brass, manganese bronze and gun-metal. The gun steel was valued for its high content of nickel and chromium which could be used with other material in the manufacture of alloy steels. For convenience in hauling, plates were cut to furnace sizes. Boiler plates and tubes were valuable as they were low in their content of phosphorus and sulphur, while the nuts and bolts used in securing the armour plate had a high nickel content.
finally Moltke was ready for her tow. The tow-rope of the leading tug was half a mile long except when quiet water was reached when it was shortened. A kitchen, bunkhouse and mess room for the crew were built on her broad bottom, and also a power-house with compressors able to maintain pressure inside the hull during the 200-mile tow through the Pentland firth and open waters of the North Sea to the Admiralty dry dock at Rosyth. Additional tugs were needed, but British and Dutch firms refused the job unless Cox would guarantee payment in case of failure. Finally, terms were agreed by the Towage, Freight & Salvage Co of Hamburg (Bugsier, Reederei und Bergungs A.G.) whose big ocean-going tugs Seefalke, Simson and Pontos arrived at Scapa Flow. The first attempt to tow out the hulk was a failure because the captains could not agree, but on Friday 18 May 1928 Moltke, upside-down, began her last voyage. The weather forecast was good when they left Lyness. Cantic was safely negotiated, and the tugs headed for Swona but were tested severely in their efforts to keep Moltke off the rocks. Sailing west they ran into bad weather which increased rapidly to a raging gale. It was impossible to turn back, and soon the tugs were being towed by Moltke in the opposite direction to which they were heading at full steam. Moltke wallowed in heavy seas which flooded the deck-houses built for the crew and the protective shelters for the compressors. Sometimes the rusty hull was completely out of sight, and in the deck-house, the water was knee-deep. As compressed air broke from the hull in gigantic bubbles she sank six feet, rolling with a list of 12 degrees on either side. They passed Snelsetter, Aith Hope and Torness and went into open sea. Then the tide slackened, the wind began to ease, and the tugs got Moltke moving again, so that the rolling diminished and the escape of air ceased. The sky began to clear, compressors restored lost buoyancy, and Sidonia, which had been brought alongside for her air-lines to be connected, was able to cast off. Before 08.00 hrs they had rounded Duncansby Head.
But they had escaped one danger only for another. Arrangements had been made for an Admiralty pilot to meet the tugs at Inchkeith. However, a Firth of Forth pilot was first on board, and when Cox arrived with the Admiralty pilot, the former pilot, who had been engaged by the German captain, refused to give way. Still arguing, the two pilots failed to notice that the Forth Bridge was looming up and that the tide, which had a five-knot run, had carried the tugs to one side of its central pier while Moltke was on the other. The tow rope caught on Inchgarvie island in the middle of the Forth, dragging gear off the stern of one of the tugs. One tug scraped the outlying rock, but fortunately no damage was done. Hastily the cable was cast off. Cox scarcely dared look, for if the centre bridge was struck by that tremendous weight, the cost of the resultant damage could ruin him. But upside-down, engineless and out of control, Moltke passed safely through the central bay, and tugs, one lashed on either side and one pulling, took her in tow again, and delivered her at Rosyth.
To be able to enter the dry dock at Rosyth, a vessel had to be canted 90 degrees in the inner basin from which it proceeded into one of three dry docks. The limiting factor for a ship’s draught was the sill of the caisson (a gate) at the inner end of the entrance lock. This had a depth of some 40 feet at high water during ordinary spring tides. With the superstructure blasted off, hulks had seldom more than a foot to spare with a draught of 39 feet, but there was always the possibility that a stanchion, or some other part hanging loose after a rough passage from Scapa Flow, could damage the sill of the entrance lock. On one occasion the dockyard officials asserted that damage to the dock had been caused, and they insisted upon repairs being undertaken. The entrance lock had therefore to be pumped out. As the dockyard had no compression pumps available, the pumps aboard the salvage tugs had to be used, and the task took a fortnight. A monumental granite mason brought from Aberdeen found a small piece of granite about the size of a saucer chipped out of the groove in which the caisson sat. He dovetailed in a new piece which the Admiralty inspector found to be less than three-thousandths of an inch at variance with the original piece. To prevent such accidents in future, piano wires were strung across the entrance lock six inches and 12 inches higher than the inner sill but positioned several hundred feet in front of it. The wires were led up the side of the lock and fixed under high tension to a spring and pointer on a heavy spring balance. Any obstruction touching the wire was reflected by the movement of the pointer, while the distance of the wires from the sill gave time for the vessel to be stopped before any damage could be done, though to bring 25,000 tons to an immediate halt entailed the ship being warped into dock at snail’s pace. If an obstruction was recorded, a diver went down to cut it away. As an additional precaution, one of the dock officials armed himself with an instrument like an outsize Alpine horn. One end rested on the piano wire, the other was at his ear. Before long he shouted exci
tedly for everything to be stopped. Much shouting followed as the warping wires brought the old battleship to a halt. Then followed a sheepish apology from a red-faced official who explained that a labourer in the docking party had been keeping time with his foot on the wire at the edge of the dock to a tune he was whistling, and the docking was allowed to continue. When she was safely docked, Cox flung his megaphone into the air, yelling with relief, and was then seen to double along the ship’s keel from which he had been directing docking operations in order to hand each of the two divers a treasury note – a bet he had lost with them that the wreck would scrape the sill upon entry. The tug Sidonian had been in attendance for five strenuous hours during the docking, and now she cast off, her raucous siren blaring the news that Moltke was safely docked. Scores of worm-like tubes, the homes of marine animals, were stuck to Moltke’s sides and she was all colours of the rainbow with barnacles and sponges, the blue of mussel shells and the varied colours-red, orange and blueish-yellow – of anemones. A large quantity of plates and glassware were brought out of her by the breakers, the Alloa Shipbreaking Co Ltd, but the most sinister find was a cat-o’-nine-tails with a short handle and a bunch of thongs.
9
The Big Ships
SIT WAS NOT UNTIL January 1930 that another attempt was made to lift Hindenburg. During the first three months of the year the docks were fitted out, new machinery installed, the plant overhauled and many other matters given attention. Meanwhile much experience had been gained on other vessels. When divers thoroughly examined Hindenburg they reported that some 500 patches were still watertight. The other 300 were then either remade or repaired. One patch alone cost £500 as the work on it had to be done under water.
To improve the stability of the vessel, the massive forward gun turret, the tripod mast and the heavy superstructure were removed. Then, to prevent her from heeling over when the bow was raised, a great concrete wedge was made 40 feet long by 30 feet wide to go under the stern on the port side where she listed. This was made from the engine-room section of a destroyer, and it was towed out and filled with 600 tons of concrete at a total cost of £2,000.
From Jutland to Junkyard: The raising of the scuttled German High Seas Fleet from Scapa Flow - the greatest salvage operation of all time Page 9