Simulation techniques for estimating ship response in waves are proposed. In this system, directional wave spectrum is estimated from time-history data of ship motion. Using the estimated spectra, ship response to all possible course and speed changes can be simulated. Information about ship response can then be predicted before a decision to change course or speed is made.
Fig.5 Instantaneous autospectra of pitch angle.
Fig.6 Estimated directional wave spectrum.
Fig.7 Comparison of predicted and measured pitching motion.
Comparison of the longitudinal bending stress power spectrum.
Results of the on-board experiments that were carried out to verify the system are summarized below:
(1) It is possible to estimate the directional wave spectra based on the instantaneous cross spectrum analysis and the recursive Bayesian modeling procedure even under nonstationary conditions.
(2) Assuming that the directional wave spectrum is stationary in time, future ship motions can be evaluated based on the previously estimated directional wave spectrum.
The authors thank the captain and crew of the training ship Shioji Maru, Tokyo University of Mercantile Marine. This work is partly supported by Grant-in-Aid for Scientific Research (No.14550858) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. The authors would like to acknowledge their support.
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AUTHOR' S BIOGRAPHY
Graduated from Dept. of Naval Architecture, Kyushu University (1984), and completed graduate course for doctor's degree (1989)
Lecturer (1989). Associate Professor (1990) of Tokyo University of Mercantile Marine.
Graduated from Dept. of Marine System Engineering, Tokyo University of Mercantile Marine (1998), and completed graduate course for doctor's degree (2003).
M.O. Marine Consulting, Ltd (2003)