The Evaluation Of Seakeeping And Application In Navigational Safety

When ship navigating in seaway, it inevitably engenders motions of swing under influenced by wind, wave, current and hull itself. For a long time , the method of ship navigating in seaway mostly reies on the experience of masters and weather routing service and developing a set of empirical navigational methods ,however without the guidance of theory ,sometimes there would appear some fatal mistakes and bring on some catastrophic results. According to the 2nd law of Newton this dissertation discusses the motion performance of ship navigating in waves and sets up a series of linear equations of ships response in regular waves in case of linearity based on the strip theory, solving the equations obtains the six degrees of free amplitude response function of ship motions in seaway. Utilize the theory of linear system of stationary stochastic processes and its recommendation on depicting wave spectra of ITTC, obtain various seakeeping factors' motion response spectral density function in stochastic waves of ship, then utilizing the knowledge of statistics obtain the changing curves of various seakeeping factors' significant amplitude with the changing course and speed, from above we can discover the connection between navigational mode and various ship's motion performance; finally introduce the scientific evaluation AHP(analytic hierarchy process) into the ship safety evaluation, set up a integral evaluated equation in which many factors are considered such as the construction of ship, loading status, and requirement ofspecialties etc, based on the evaluated equation ,the optimum course and speedas well as the danger range can be obtained, which would be a good advice tomaster, so develop a set of navigational methods which put empirical andtheoretical navigational methods together ,which can warrant the ship safety andaccomplish ship task.