Fourth Crandall Drydock For Belgium Placed In Service
The Port of Zeebrugge, Belgium, which is presently undergoing considerable expansion, recently inaugurated a new 1,200- ton Crandall r a i l w a y d r y d o c k, with a side transfer system to enable as many as four vessels to be docked simultaneously. The construction was undertaken by the Entreprises Maurice Delens of Brussels, using the general and detail design of Crandall Dry Dock Engineers, Inc. of Dedham, Mass.
This facility, the first of its kind in Zeebrugge, will permit the substantial fishing fleet of the area, as well as other harbor craft, to be drydocked in its home port rather than having to go to Ostend or Antwerp. It also will encourage a shipbuilding industry to develop in the Prinsfilip dock area where the drydock is located. Sitting in a wet dock behind locks assures a constant water level within a range of 20 centimeters, permitting 24-hour docking.
The brackish water is too salty to freeze readily but not salty enough to support marine borer life.
The railway has foundation and underwater ways of azobe timber from Cameroon, and the inshore portion is of reinforced concrete. A curved track causes the cradle to be rotated from its inclined attitude submerged to a horizontal position full up that permits easy side transfer.
A standard Crandall low-friction roller system is used for both hauling (with a single 2%-inch chain) and transfer. There is a cradle 72 meters long by 16 meters wide, with drafts over blocks of 3 meters inshore and 6 meters outshore. It has a capacity for concentrated loads of up to 35 tons per meter, with transfer limited to 24 tons per meter.
Because the outshore section can operate independently, there are forward latches to secure the bow cradle, and there is a wire rope bridle to keep the roller system in position.
A unique system for bilge block operation on the transfer cars is capable of reconnection so as to work directly on the main cradle. This latest improvement, never used previously, has proved very successful and saves considerable time and labor in the transfer of vessels.
A vessel to be transferred sits on up to nine separate cars. It is propelled sideways by two independent hydraulic-powered drums, using 22-millimeter wire rope with 3-part tackle, a t t a c h e d at two points to the vessel itself. For security against wind forces, the transfer cars are provided with holding clamps on both the cradle and the transfer berths.
The project was financed by the national government of Belgium for the c i t y of Brugge through the Department of Public Works (Service de la Cote), and managed by Ir. Kerckaert, director, under the overall controll of Ir. Simoen, Inspector General. Fabrication of structural steel was done by Victor Buyck of Eeklo; the hauling machine with all its electrical controls was manufactured by de Pecker of Gent, using certain elements supplied Crandall, while all civil works were carried out by Delens. Underwater work, particularly pile cutting and track i n s t a l l a t i o n, was s u b c o n t r a c t e d to Benelux Divers, Inc. of Antwerp.