Some Analysises for the Shifting Work of Large Stern Block

Abstract

The large stern block of the 38, 000 DWT tanker (total moving weight 2, 800T) was shifted laterally and longitudinally on March 12, 1957 in the shipyard of Kawasaki Dockyard Company.
Before the planning of the above-mentioned shifting, authors made experiment on the frictional coefficient and characteristic of the grease to be used. As a result of this experiment, it was found that the frictional coefficient of the grease is very large at the beginning of the shifting, but suddenly decreases and becomes constant within 0.0110.017 after moving the distance of 20mm, the pressure on grease is 2030 T/M² and so it was ascertained that the greased sliding way could be used for the shifting work, when the shifting equipment, which is planned based on the frictional coefficient of the grease as 0.029 in case of lateral shifting, and 0.010 in case of longitudinal shifting, is reinforced by the pushing arrangement at the start of shifting.
Authors also planned the lateral shifting by pulling the center of resistance position by means of only one pulling wire rope.
As a result of the analysis of miscellaneous measurements and recordings of the actual shifting, it was also ascertained that the above plannings and results almost agree, namely the frictional coefficient of the grease was max 0.029 approximately in case of lateral shifting, min 0.010 approximately in case of longitudinal shifting, and the difference between lateral pulling position and the center of resistance position was within±200mm.