Engineering Wonders of the World
Volume I

410 ENGINEERING WONDERS OF THE WORLD. Fig. 2.—BARCELONA DEPOSITING DOCK, WITH SHIP LIFTED, READY FOR TRANSFERENCE TO THE GRID, WHICH IS SHOWN ON THE LEFT OF THE PICTURE. To the right, and attached to the wall of the dock, may be seen the floating outriggers which gave stability to the dock. capable of raising vessels of 8,000 tons only, whereas at the present time there are in exist- ence docks of this type with, a lifting power of 36,000 tons. Floating docks are also rapidly becoming more numerous, one firm alone— Messrs. Swan, Hunter, and Wigham Richard- son—having built no less than five in 1908. This famous company, it may be remarked, have to their credit the construction of a greater number of modern floating docks than all the other builders in the world combined. Several of the docks illustrated in this article were turned out from their yard at Wallsend- on-Tyne. Foremost among the considerations which have led to the rapid increase in the number of floating docks is that of reduced initial cost as compared with the exca- Low Cost and va^ej graving dock. The price Rapidity of floating dock can be fixed Construction. ® with certainty. In construct- ing a dock excavated out of the land, however, an ample margin must be allowed for possible accidents to the site by ground springs or wash-outs. Naturally, much depends on the particular requirements to be fulfilled, the condition of the site, the depth of water avail- able, etc. ; but it may be taken that, except where the conditions are entirely against the floating dock, this type is much less costly to construct than the excavated' dock. Another important reason why floating docks are likely to become still more numerous in the future is the rapidity and certainty with which they can be constructed. As an example of this, we may instance the floating dock of 11,000 tons lifting power built at Walls- end some years ago for use at Stettin. This dock was launched seven and a half months after the signing of the contract for its con- struction, and eighteen days later the structure had been towed to Stettin and had success- fully lifted the liner Spree (Fig. 11). Three or four years are not infrequently occupied in tho construction of an excavated graving dock, and in one case known to the writer, so great were the difficulties encountered, seven years elapsed before the dock was ready for work.