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Floating Dry Dock for Montreal | Description of the Structure Which Messrs. Vickers Have Built for Their New Canadian Establishment BOORS,., Vickers; Goa last IVA cook started on her voyage to Canada, the floating ship dry dock built at their naval con- struction works at Barrow-in-Furness for their new establishment at Mon- treal. This dock is one of the largest yet built. It is capable of docking the largest existing vessel in the British. navy. It. is .of the. double- sided self-docking type, on the prin- ciple known as the "bolted sectional". 'It consists of a pontoon or lifting portion of the dock, and two parallel side walls, built on to and forming part of the same, and the whole length is divided into three complete and separate sections, which, when bolted together, form the complete dock. « These * sections "are "so .ar- ranged that when the dock is separ- ated into its three parts, any two of them can dock the remaining third between them. For this purpose each section is fitted with its own inde- pendent pumping machinery, so that it can also act as an independent unit. The general dimensions of the dock are as follows: Bt, in Length over "platforms 5 605) S 600 Length 'over, pontoons: <4) 3) 44.4.5.) 550 Width over allo) cease ee ee 135 Depth »of "pontoon, at. center... i.:5... 17 Length of side walls) oon oan 6 470 Height of side walls above pontoon deck Width of side wall at base.......... 17 Width. of 'stde wall at 'topic... 7.0... 12 Clear width between roller fenders... 100 Draught' of 'Vesselaic. 065 eee ae 27 Lifting capacity, tons The construction of the dock is such as to make it suitable for lifting a modern British battleship, the pon- toon deck being specially stiffened to allow it to support a large por- tion of the weight of the vessel on side or bilge,: as well as central, keels. Divided Into Three Sections The pontoon consists of a. rect: angular structure plated in all round with the exception of the portion of the deck which comes directly under the walls, and stiffened internally by longitudinal and transverse' girders. It is divided into three sections by joint chambers. The two end sec- tions have their outer extremities built in the form of a point or bow terminating in a working platform carried on plate and braced girders. The bottom plating, except under the walls, is arranged to run transverse- ly,and is connected to the plating of the sides and points by chine angles; the top or deck plating, similarly ar- ranged, is connected to the face of the side wall by chine angles. The pontoon is divided into four com- partments by three longitudinal in- tercostal water-tight plate-bulkheads. Transversely the pontoon is divided into 54 bays, 20 in the central section and 17 in each end section, by trans- verse girders, consisting of plate- bulkheads. In the compartments un- der the walls the plate-girders are replaced by special lattice-girders. In addition to the bulkheads, the deck and bottom platings are stiffened by means of a series of longitudinal frames which run fore and aft over the length of the pontoon, intercos- tal between the transverse girders. In addition to the transverse lattice- girder under the wall, intermediate transverse ordinary frames are fitted 2: ft. 6 im apart, and are prolonged upwards, forming the ordinary frames of the walls. The central bulkhead between the transverse girders 'is stiffened by vertical "breathing" plates, which are well stiffened and connected to a longitudinal curtain- plate. Outside this framing of breath- ing plates and longitudinal curtain- plate, the pontoon deck and bottom are stiffened by longitudinal fram- ings consisting of angles, connected to the transverse bulkhead stiffeners by gussets and diagonals. These framings extend to the line of the face of the wall. In the center sec- tion several of these frames are pro- vided with plates riveted to them, to take the load from the side keel- blocks. The intermediate longitudinal bulkheads are formed of _ vertical plates, intercostal between the trans- verse girders, to which they are at- tached, as they are also to the top and bottom plating. To facilitate the complete withdrawal of all water in the pontoon, shallow troughs are fit- ted, which form a gutter. Horizontal Plating The walls of the dock are plated horizontally and have a batter on the face or inside wall. The top deck of the walls is plated longitudinally, and is connected to the side plating. by double-chine angles. An _ engine- deck, on which is placed all the ma- chinery of the dock,is fitted about 16 ft. below the top deck, and is ar- ranged water tight. Each wall is divided, in addition to the joint cham- bers, into ten water-tight divisions by plate bulkheads, coming in line with the bulkheads in the pontoon, of which they are a continuation. At each end of the wall a docking land is formed, on which the' central por- tion can rest when being self-docked. The framing of the walls is of two types, braced and ordinary. In line with the transverse girders of the pontoons, of which they form -- a continuation, the frames consist of single angles stiffened by vertical web-plates, the front and back frames being cross-connected by a series of diagonals and gussets. The ordinary frames of the walls consist of single angles back and front, cross-connect- ed by a series of horizontal struts. Special stiffening is fitted in way of the machinery. About 1 ft. below the top deck a running deck is provided for enabling ropes to be easily hand- led and run from one end of the dock 'to the other outside the stan- chions. Timber-heads and such fit- tings required in berthing vessels are fitted on this deck. At a distance of about 15 ft. and 29 ft. respectively be- low the running deck, two further stages, known respectively as paint- ing and shoring stages, are provided. Can Work in Independent Units Each end of the central section and each square end of the terminal sec- tions is provided with a joint cham- ber, by means -of which the sections can be joined together or parted. For the purpose of dealing with commer- cial vessels, which ordinarily will not have the weight or dimensions of the Dreadnoughts, the dock has been designed so that it can work when required in two independent units of unequal size, and to facili- tate the rapid connection of the two portions, cast steel rocking joints, in, the form of knuckles, are fitted at the level of the keel blocks. The pumping installation of the dock is driven by steam generated in boilers catried on the .dock itself; Each section of the dock has its own com- plete pumping installation, and each installation consists of two boilers and two engines and pumps installed