Simulation Study Of The Slewing Motion Of A Ship At Anchor In Shallow Water Under The Effect Of Wind And Current

In long-term practical activity, the slewing motion is much harmful for the mooring or anchoring ships. In practice, especially when the ship mooring or anchoring in the relatively closed, no good shelter anchorage, the phenomenon of slewing motion under the effect of wind and current is very obvious, in this case, the severe partial swing motion and the consequences are very serious. Therefore, it is an important practical significance to master the phenomenon of slewing motion under the effect of wind and current for ensuring the safety of the ship at anchor.The slewing motion model for the vessels at anchor under the effect of wind and current is a low speed, large drift angle mathematical model, in view of this, the slewing motion mathematical model for the vessel at anchor in shallow water under the effect of wind and current has been established using the MMG separation of modeling ideas, which has bases on low speed, large drift angle hydrodynamic model of Yoshimura and adds the shallow water amendment. The equations of the motion were solved by a four-order Runge-Kutta method. The maneuvering motion simulation platform and simulated the slewing motion of the ship at anchor has been built by taking advantage of SIMULINK toolbox in MATLAB language. Analysis and comparison of the simulation results obtained in different wind speed, different current speed, a chain of different length, different load conditions, different trim and different ship types on the slewing motion of the ship at anchor, the results of study show that:affected by wind and current, the role of the wind is more obvious than current, the slewing motion of a small tonnage vessel is acuter than the large tonnages. Therefore, the navigator should focus on the influence of wind, and especially pay attention to the small tonnage vessel and the vessel with large wind area.This thesis briefly analyzes the hazards of swing motion and solutions under forward research work, and referred to the dynamic chain tension calculation formula of Kinzo Inoue, the chain impact tension calculation formula of Iwai Sato while analyzing the dynamic security of the ship at anchor. Meanwhile, this thesis calculated the limited wind speed of the safety of ships and provided corresponding security measures.