抄録
Several papers have been presented on the estimation method of wave spectrum with frequency response function of a ship and its measured motion in waves. This method is known to give valid estimate of wave height in moderate seas. It is important to know whether it is also valid or not in very rough seas, but there are few papers on the method in very rough seas. Fullscale measurements of wave impact forces and hull response of a ship have been conducted in very rough seas. In this paper, estimations of encountered waves in very rough seas were presented with measured data of a ship motion and its frequency response function in head seas. Pitching and heaving motion were used as a ship motion for wave estimation, and estimated two waves were compared. Frequency response functions were derived from ordinary strip method (O.S.M.). Nonlinear ship response analyses were carried out with estimated waves to confirm the estimated waves. Caluculated results and measured ones were compared. Results obtained were as follows: (a) The wave estimation method with measured data of a ship motion and its frequency response function was valid in very rough seas under careful attention. (b) Simulations of ship motion in waves were made with estimated waves, and good coincidences were obtained on measured ship motions and estimated ones.
