Long time ago, people began to study the performance of ships in still water. But, varieties of facts suggest that ships with excellent performances in still water would not function well in waves. Seakeeping performance is becoming of increasing importance. There are two basic ways to study seakeeping performance of ships: theoretical method and experimental method. The method based on theory focus on the foundation and resolution of various differential equations of ships in regular waves, and prediction of ship motion from the resolution of equations. The introduction of strip theory had greatly promoted the theoretical analysis of heaving and pitching motion, but it cannot give satisfactory results for rolling motion. Beside theoretical analysis, doing experiment is another important way of seakeeping research. Especially for certain problems without theoretical answers, experimentation is the only way for analysis. This paper did some research on the rolling motion of pentamaran through a method combined both theoretical analysis and experimentation. A method for analyzing the rolling motion of multi-hull ships has been put forward. Firstly, an automatic controlled free-running multi-hull model experimental platform has been designed and built. With the prior knowledge, the equation of non-linear rolling motion with undetermined coefficients has been established. Approximate equation for rolling motion of pentamaran has been given through identification with the data collected from model tests. Identification method is an optimization method based on Genetic Algorithm, and it would search the best results with given ranges of parameters. At last, the method has been proved feasible after analysis of the results, and provided some experiences and suggestions on the seakeeping analysis of multi-hull ships.
In recent years ship seakeeping was paid more and more attention, so the ship with better seakeeping was becoming research hotspots. Ship seakeeping is a subject to study ship movement rules in wave.
