Plate XLV.THE GRAVING DOCK.Larger image
Plate XLV.
THE GRAVING DOCK.
Larger image
The ships launched are completed in the fitting-out dock, constructed about two years ago, and illustrated on Plate XLIV. The engraving shows H.M.S.Argyllunder the big jib-crane. This dock has a length of 560 ft. and a width of 172 ft., and opens directly into the channel of the Clyde. The depth of water is never less than 28 ft., so that warships are afloat at all states of the tide. A prominent feature in the view is the crane, which was supplied by Messrs. George Russell and Co., Limited, of Motherwell, and lifts 120 tons at a radius of 70 ft. It is carried on concrete foundations and piers, which rise 20 ft. above the level of the quay. In addition to the pier for carrying the mast of the crane, there are similar supports for each of the back legs through which the crane is anchored.
One advantage of the derrick type is that the crane may be placed close to the edge of the quay; in this case the centre is only 7 ft. from the front of the wharf, so that the full load of 120 tons can be dealt with at an effective outreach of 63 ft. from the quay. The maximum radius of the heavy purchase with a load of over 60 tons is 90 ft., and of the light purchase gear, with a load of 10 tons, 98 ft. The minimum radius of the crane is 25 ft. There are four sets of gear: for lifting heavy loads, for raising light weights, for derricking the jib, and for slewing; a separate controller of the enclosed tramway type is provided for each. The main hoisting and derricking motors are of 50 horse-power, and the others of 35 horse-power. The speed of hoisting 120 tons is 5 ft. per minute, while a 10-ton load is raised at the rate of 40 ft. per minute. Automatic brakes are fitted for the slewing motion, and powerful hand-brakes for the hoisting and derricking gears. All motions are controlled by oneman in the steelhouse fixed to the mast of the crane 56 ft. above the quay level.
There is on the opposite wharf of the dock a 20-ton travelling electric crane, and throughout the Works there are many portable and hydraulic cranes, in addition to the hydraulic and other cranes commanding the machine tools.
Reference may here be made to the Company's graving dock, illustrated on Plate XLV., adjoining page 101. The length is 360 ft., and it is largely used for docking ships for repair, as well as for cleaning ships preparatory to trial. Our view shows a torpedo-boat destroyer in the dock. The pumps for the emptying of the dock are electrically driven.
We may return now to our narrative of the construction of a ship, and deal with the supplementary departments, including those of joiners, smiths, plumbers, sheet-iron, and other workers.
Wood-work forms a large and important item in most of Scotts' ships, as many of them are for passenger service. We illustrate on Plate XLVI. one of the saw-mills. It is self-contained, having its own power plant, including a compound engine, having cylinders 15-1/4 in. and 27-1/2 in. in diameter by 44-in. stroke. There are four vertical saw frames, the largest having a 36-in. frame, six rollers, and two bogies to take in the heaviest logs. In addition, there are circular saws, ranging up to 6 ft. in diameter, a swing cross-cut saw, special planing, moulding, and turning machines to do heavy work, and saw-sharpeners, grindstones, punching machines and anvils to carry out all repairs and fettling of the blades, etc. There are also large steam-heated drying stoves, and a timber-drying yard of about three acres in extent. The overhead travelling cranes range up to 5 tons capacity, and the rails on which they run are extended on columns across the yard. The saw-mill is the largest and best-equipped in the district, and does the sawing and planing of timber for three of the largestshipbuilding yards, as well as the general work for two other firms.