The Comprehensive Evaluation Of Seakeeping Based On The Theory Of Grey System

A great lot of facts indicate that the navigation performance of ships is good in quiet water, but not always good in waves. Whether the performance of ships is superior or inferior mainly depends on their performance in waves. The seakeeping of ships has become an important criterion which can scale the navigation performance of ships. It is a significant task of researchers and designers to evaluate a ship, especially a new ship design, which possesses excellent seakeeping or not. Because there are many factors which affect the seakeeping of ships, moreover the seakeeping is not the result that single factor affects , but is the result that all factors affect together , we must look for a scientific synthetic method to evaluate the seakeeping of ships based on the effects of all factors. Only by this way could we obtain a correct conclusion that would give the ship designr and masters an effective guidance.This paper embarks the research of the comprehensive evaluation method of seakeeping and its application, utilizing the fruit of the academic prediction of seakeeping. The research of this paper includes three parts.Firstly, the research introduces a computational method of comprehensive evaluation indexes-the percentage of ship task and the percentage of anticipant speek of ships,which can reflect the entire performance of seakeeping of ships, then applies the method to calculate and analyze the indexes of a ship based on its prediction results, moreover obtains some significant conclusions.Secondly, by thinking over the characters of seakeeping and the research results of some systemic evaluation methods, the research finds out the link of grey relational analysis and the evaluation of seakeeping of ships, then introduces the theory of grey relational evaluation into the seakeeping evaluation of ships in waves firstly, moreover puts forward a new comprehensive evaluation method—grey relational evaluation method of seakeeping. Two application examples of this method are illustrated. Analyzing the results of these examples make known: the method introduced in this paper is concise and valid, and give the designers and masters of ships an effective guidance.Finally, the research compares the grey relational evaluation method of seakeeping with the comprehensive evaluation indexes of seakeeping and the evaluation method of seakeeping based on an evaluated equation. The comparative results indicate that the grey relational evaluation method of seakeeping is an effectively comprehensive evaluation method, and is a valid tool to research the object interrelationship. This evaluation method synthesizes the virtues of AHP(analytic hierarchy process) and grey relational analysis. It can effectively solve the problem of comprehensive evaluation with many targets.