Some Investigations on Sinking and Refloating of Dock Gate Vessels

Abstract

This paper deals with the sinking and refloating motion of dock gate vessels with the aim of clarifying the relation among the draft of vessel, the quantity of ballast water, speed of and time required for sinking and refloating, and stability of the vessel at the following typical stages. (1) 1st. stage of sinking : the vessel sinks charging only lower tank with ballast water. (2) 2nd. stage of sinking : the vessel sinks charging both lower and upper tanks with ballast water. (3) 3rd. stage of sinking : the lower tank is filled with ballast water and the vessel sinks charging only upper tank with ballast water. (4) Stage at which the vessel is sitting on the entrance ground of a dock. (5) 1st. stage of refloating : the vessel begins to refloat rapidly. (6) 2nd. stage of refloating : the vessel refloats discharging ballast water from upper tank.