The New Shipbuilding Method by Shifting Large Stern Block

Abstract

Kawasaki Dockyard Company, breaking out of the old shell of hull building technique, has adopted a new shipbuilding technique conceived under a new idea. Under this new idea a large stern block previously built is shifted on to an adjacent building berth and there outfitting of the stern parts is continued. In parallel with such work the rest of the hull construction and the outfitting work are kept on while engine installation, electric wirings, and deck outfitting are completed, and then the ship is launched.
The objectives of such procedure are to shorten the time needed for all the outfittings, which are usually carried out on the launched ship moored to a wharfside, and also to do away with subsequent docking.
Briefly speaking, the summary of shifting work is as follows : The 2, 800 T stern block is pulled transversely along eight rows of greased sliding ways and then made to slide down two rows of greased standing ways longitudinally by means of a single wire rope, respectively.
The pulling arrangements including wire and winch etc. are planned on assumption that the frictional coefficient of the grease during the shifting is 0.03. The speed for pulling and sliding is fixed at 500mm/min.
Various measurements are carried out during the shifting. With regard to the stresses caused in the hull during the shifting and readjustment of its position, their maximum values in tension and compression are found to be 2.1kg/mm² and 0.8kg/mm², respectively, which do not differ much when compared with those (1.9kg/mm² in tension, 3.4kg/mm² in compression) measured in hydraulic test of the same stern block. So the figures are by no means serious as hull stress.
Frictional coefficients of the grease, which were experimentally within the range of 0.0110.017 for 20T/M² pressure, were found to be actually 0.029 in maximum, 0.010 in minimum for the lateral shift and 0.022 in maximum, 0.010 in minimum for the longitudinal shift, respectively.
These values of coefficient obtained in actual shifting corresponded, in minimum side, to those of experimental result.
Sand jacks were used in making minute adjustment for the final position of the stern block when it was settled on the berth after a long shifting work.