Analysis And Research On Self-Righting Performance Of Medium And Large Boat

The safety performance of the ship is the first consideration in the design of the ship.the stability of the ship is undoubtedly an important factor in the study,which is mainly divided into initial stability and large inclination stability.At any angle between 0 and 180 degrees of heeling of the ship can rely on their own ability to return to the original state of balance,indicating that the ship has the function of self-righting,the study of the ship's self-righting ability is to further study the ultimate stability of the ship on the basis of the ship's large inclination stability,greatly improve the safety of the ship,and at this stage the study of the ship's self-righting ability is relatively small.Therefore,the study of ship self-righting ability is of great significance.In this paper,the self-righting ability of a 20 m long medium-sized and large boat in static water and waves is studied.1)the self-righting process of the ship is analyzed.it is considered that the restoring moment arm of the ship at any angle between 0 and 180 degrees of inclination is greater than zero,and the calculation method of the self-righting capability of the ship is studied.2)the three-dimensional calculation model of the target boat is established by maxpsurf software,and the curve of the restoring force arm of the target boat with or without superstructure is calculated.the reason why the target boat can realize self-righting is analyzed,and then the variation law of the target boat with the state of trim,displacement and center of gravity is calculated and studied.3)the calculation method of restoring force arm of ship in waves is studied.the water pressure on the wet surface of ship is calculated by describing three coordinate systems of wave motion and relative motion of ship and analyzing the reasons for the change of self-righting ability of ship in waves and still water.the instantaneous static equilibrium equation of ship after heeling is solved to determine the instantaneous parameters of ship after heeling in waves.the restoring force arm of ship in waves is calculated based on froude-krylov assumption.At the same time,the change law of self-righting ability of the target boat in the middle of the wave crest or trough is studied.