Software Design For Assessment Of Large Surface Warship Seakeeping Performance

Seakeeping performance, which is defined as the capability of a ship to remain safe when it operates in bad sea condition, is considered as a very important factor when the overall performance evaluation of a ship is carried out. Wave load on a ship can generate a lot of adverse influences, such as unwanted motions, slamming, green water on deck, ship speed loss and wave-induced bending moments. Such harmful influences destroy the seakeeping performance in every aspect:safety, habitability, operating capability, etc. Recently, because more and more researchers realized that the seakeeping performance for a ship operating in wave condition is very important, a lot of achievements have been made. Now, along with the need of large ships and super large ships, how to establish a way to evaluate the seakeeping performance in the phases of preliminary design and detail design becomes an important subject. An effective evaluation way can also makes contribution to the economic income.Good seakeeping performance is gained in good design. Now the seakeeping performance design of large surface warship is carried out during the detail design in which the lines and main factors are already gained, if figure changes were made considering seakeeping performance, it would increase too much cost and workload. So an effective way to consider the seakeeping performance in preliminary design when lines and main factors remain unknown is wanted very much. A method using experience-based formula which gained by academic calculation combined model test results is established in this paper, this method is proved effective when execute seakeeping performance design of similar ships during preliminary design.This paper based on the fruit of the academic prediction of seakeeping. First, according to the theory of motion performance of ship navigating in waves this dissertation sets up a series of linear equations of ships response in regular waves 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, obtain various seakeeping factors'motion response spectral density function in stochastic waves of ship, then useing 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. Then apply the wave data of ocean environment, according to the related theories, to calculate and analyze the prediction of ship's seakeeping, moreover obtains some significant conclusions. Then based on the theory we build the emluator to calculate every factors of seakeeping performance. Obtained by regression calculation and the existing empirical model ship seakeeping, and by comparison with other empirical models obtained the feasibility of this empirical model; Finally, the research introduces a computational method of comprehensive evaluation index which can reflect the entire performance of seakeeping of ships, then apply the method to calculate and analyze the percentage of the task time of ships based on the wave data of ocean environment, and also obtains some significant conclusions.