A Stochastic Model for Evaluation of Seakeeping Performance

摘要

The stochastic process model of the long-term statistics of shiprnresponses is proposed. We have investigated the correlation betweenrnthe wave height and the standard deviations of the shiprnresponses at sea. Analysing the monitored ship response datarnon board of a container ship and a bulk carrier, we have foundrnthat these standard deviations have three stochastic properties:rnthe Markov property, regression to equilibrium, and linearity ofrnfluctuation. The stochastic process model of the ship responsesrnis constructed based on these properties. This model is given byrnthe stochastic di?erential equations, and the probability densityrnfunction is obtained by the Fokker-Planck equation. Generally,rnthe stochastic di?erential equation is di±cult but this model isrnnot di±cult because it has only three parameters. Furthermore,rnwe explain long-term prediction and simulation of ship responsesrnby this stochastic model and introduce a method of evaluatingrnthe monitoring data of ship responses on board.