Study on the pitching motion model of a high-speed monohull ship based on test

In this paper, the author took a type of high-speed monohull ship as the research object, designed and added a bulbous bow of original ship by the principle of best comprehensive performance, made two 2.7 meters long scale models. Then conducted a series of pitch decay tests on condition that two ship models were in different drafts and tilt angles, established a mathematical model by the method of system identification based on genetic algorithms, developed a system identification software, made an analysis on pitching motion mode. The pitch motion differential equations of the two models in different drafts and initial tilt angles and the changing regularities of hydrodynamic coefficients with draft and initial tilt angle were obtained and comparatively analyzed. Through the research, the method and results can provide technical support to the deeper analysis and designs of this kind of ship.