Stability And Navigating Safety Of A Ship In Following Seas

When ships navigate in following seas, the accidences such as loss of control,large amplitude rolling and capsizing will easy occur. Loss of stability is the main reason causing these accidences occurs in following seas. This thesis research the stability and navigation safety of the ship in following seas and try to find the reasonable and practical method to forecasting the stability and evaluation the navigation safety of the ship in following seas.On the basis of the ship six degrees of freedom maneuverability equation, the author set up the ship's rolling equation in following seas, the equation including the inertia force,the damping force,the hydrostatic force and the Froude-Krylov force. Solving this equation to get the ship's movement in following seas,the ship-wave relative position on the wave surface and the wave line of the ship hull,the action line to the center of buoyancy in any floating condition and then get the ship's restoring arm through the action line passing through the center of buoyancy and the center of gravity. Analysis the characteristics of stability in following seas from comparing the difference of the ship restoring arm between still water and following seas.The author researched and calculate the stability and lose of stability of the model ship in the regular wave in following seas, consideration and analysis the stability and the basic stability changing rule of the model ship in certain typical wave lengths,wave heights and wave incidences.To fully understand the factors that impact the navigation safety of ships in following seas, the author carry on the ship model tests in the model ship basin, such as the wave force experiments in following seas, rudder's hydrodynamics force in following seas and self pilot experiments in following seas, analysis basic characteristics of ship's movement in following seas and the objective factors that impact navigation safety in following seas.On the basis of the stability in following seas and experiment research of the model ship in following seas, the author evaluated the model ship navigation safety in following seas by fuzzy comprehensive evaluation method based on the factors that affect the ship's navigation safety in following seas. The author gained some conclusions that can be referenced in ship design and research...