Slew Cranes in Shipyards: A Study

The purpose of this study is to examine the various types of cranes in current use in shipbuilding yards round the world, and to make a recommendation on which type is most cost effective for installation in U.S. shipyards. In-the study particular attention has been paid to the four aspects of crane design that impact most significantly on shipbuilding operations 1 double-boom as opposed to single-boom design 2 column mounting as opposed to turntable mounting for the slewing part of the crane and for column mountings, the kind of bearings to be used 3 balanced boom as opposed to unbalanced boom design and, most important, 4 the provision of level luffing as opposed to traditional luffing. Since these distinctions may not be universally familiar the purpose of Section 4 of the study is to outline the theory of operation of each system. The short sketch of crane development on both sides of the Atlantic is intended to explain this information gap why is it that U.S. operators are often so unfamiliar with developments in crane technology outside the United States Having filled in the background, the purpose of Section 5 is the detailed examination of five actual cranes with a view to establishing first the investment cost of each type its cost-to-build and then its maintenance and running costs. Operational efficiency, i.e. , the speed, accuracy, and downtime of each crane type, are also investigated. Finally the safety and training of the operator are considered as investment factors. It is intended that the data and conclusions offered in this report would be of value to any U.S. shipyard during the planning and scheduling of replacement cranes.