WORK AT SCAPA FLOW

Hauraki Plains Gazette, Volume XXXV, Issue 4744, 29 August 1924, Page 4

WORK AT SCAPA FLOW

RAISING THE GERMAN FLEET. DIFFICULTIES FOR THE DIVERS. During the war the British salvage successes were notable for the recovery of German code-books, which are still a secret. The mew chapter opened with the “Laurentic Operations,” and new (writes a special correspondent of the London “Observer”) another mighty task is beginning—the raising of the German Fleet at Scapa Flow, It will mean seven years of hard toil. Many have said, “Why do they need to salvage the German Fleet?” Well, the old saying is, “Practice makes perfect”; and suc : cessful experiments in these operations may mean to us more than does the Laurentic gold. Never have we had, and perhaps never shall again have, such an opportunity of testing our salvaging capabilities. The equipment of the vessels devoted to the salvage work on the German. Fleet comprises a bewildering assortment of engineering appliances, all immensely powerful, all of the simplest possible construction, and all made of such material and treated in such a way that being in or under water for a few days or even weeks does tnem no real harm. There are pumps capable of drawing up over a ton of water a second, and not given to shirking if the water is muddy or sandy ; hammers, drills, and rivetters, worked by pneumatic pressure, and striking about 1500 blows a minute, either under water or above. Electric lamps illuminate the gloomy recesses of a sunken vessel’s hold, or blaze above the dark water when the lost ship has risen again to light the workers as they secure their prize for towing into port. USE OF EXPLOSIVES. But more wonderful than all is the use made of the most powerful explosives. Dynamite charges, carefully graduated, are used either for clearing away an obtruding pinnacle of rock, or attached to the ragged edges of a rent in the side of a sunken vessel for blowing those edges smoothly off in .order to allow a patch to be built over it. For certain cases there will be pontoons, hollow iron tanks of varying sizes, their lifting power, carefully noted, and their shapes so arranged that they fit closely to the sides of the wrecked ship. • These are secured to the -ship, and can he sunk and. fastened to the sides, ofi the vessel under watei by the divers, then pumped out and made airtight. They then immediately exert all their enormous liftin'; power. There is the salving ship herself, a vessel not too large, but’ of immense strength of hull, of great engine power for towing purposes, and equipped with mighty cranes and derricks for hoisting weights up to fifty tons each. An all important item is her electrical installation for the working o£ searchlights and arc lights of great power. An air-compressing plant is necessary for the working of the pneumatic tools which form so important a part of the diver’s equipment. Th< salvaging of a battleship is a totally different .proposition from that of a merchant ‘ vessel. Few people ever think of the enormous masses of metal, some over a couple of hundred tons .'ii weight, that are to be found in a modern 'battleship, .the lifting of which taxes all the resources of even a dockyard. If every ship in Scapa Flow were in the same position the task would, be easy, but that is not so. Some idea of the task may be gathered from the fact that all ships lie in a - different position. For instance, the Hindenburg is standing upright; the Derfflinger nearly on her side; the Seydlitz bottom up; cruisers with their “bows” in the air; and ihe others in various positions. This shows that ev.ery ship will need its different methods. Let us take the Hindenburg oh an even keel. With the depth of water and the plan of the ship a coffer dam can be built right round her upper works-*—an immense superstructure, watertight, and reaching the surface of the water. After the divers have closed all holes the great rjumps can be set to work and tiie shiip brought to the surface. Many shi®s have been salvaged in this way.. With the Seydlitz it is a different matter altogether, for had she also gone down on an even keel pumps, and plenty of them, would soon have brought her up again, but the 24,000t.pn si-ip has been overturned, and the righting of a capsized vessel is always . a ticklish ■ job. The main advantage in this case is the space in which to; move derrick, for it is essentia! that the lifting craft should be able to move freely all round the capsized vessel if she is to be brought to; the surface again. Much blasting Biay have to be done with explosives, getting, rid of the masts and other obstructions, for that is the first step towards salvage. Then the divers will be sent into the interior of the ship with orders "Close all port-holes and every other opening you can find.” By this time, however, the ship will have sunk some distance into the ooze, pud many tons of mud will, have to be shifted to the port-holes and other openings, which makes things unpleasant and difficult for the divers as well as adding considerably to the weight to be lifted. The port-holes, owing to the ship’s position, will be no easy task to get at, but by using compressed air and turning powerful jets of water on the mud one by one can be screwed up. It is a nerve-trying, risky work, and the civers have to study hard to get the "hang” of the ship before they venture down. The floors of the cabins of many of the ships, of course, will now be the walls, and the Avails have become floors, the doorways making pits for the unwary to Pall through. FNDER-WATER BORING. When a diver falls tragedy may easily occur, so all the.time the men have tr be on the alert. Coupled with these drawbacks is the fact that in the interior of the ship the water thick with mud, making it impossible to see, and the divers have to trust

to their fingers—like blind men they will grope about, relying upon their sense .of touch to tell them that things are all right. It will be a mighty task to roll over this 24',000-ton carcase of a ship, and it seems at a glance impossible that such a think can be done ; but a success will be achieved. For a ship lying on her side, and which has now dug herjslef into the yielding ooze, it will be essential to remove all the mud between her keel and the bottom in order to give her free movement. The oxy-actylene blow-pipe may prove a great advantage in making holes through metal bulkheads, or the oxytoi ch, by which metal can be actually burnt under'water. It seems incredible to think of heating iron to melting point when surrounded by a mass of water, but the flame is encircled by a cylindrical jet of air that blows away the Water. The heat is very intense and highly localised, and as a result the temperature is raised enough to heat through the iron and

steel. Plunge a match into water and it goes but. Even .the blaze of a ship alight from stem to stern is put out as soon as she sinks. The end of the electric torch used is shaped something like a cup, in the centre of which is the electric arc, which generates a heat of 6700deg. Fahrenheit. Around the arc is a scries of apertures, arranged in a ring, through which the highly compressed gas is delivered. The intense heat o f the gas—about three thousand degrees—drives back the water from within the cup and reduces it to tsteam, thus leaving the waterless space for the electric arc to work in. The diver holding this’ torch against the steel can cut circular holes fourteen inches across in about ten min- , tiles. A remarkable point is that this torch produces such a dazzling light . in spite of the inky mud-charged . water tfiat the divers have to arrange ! shield over the glass fronts of their I heldmets in order to protect theii I eyes from the glare.