Understanding and Prediction of Ship Motions 

 Relative error 



3 4 5 ^6 7 



Reqwnse of roll to wave height 



Figure 14 



the results obtained by using Wj are shown here as examples^ The amplitude 

 gain in roll was calculated as the ratio of the roll angle to the wave slope in 

 Fig. 12, from the original results of gain of roll angle to wave height as is 



shown in Fig. 14, where the result obtained by using 

 The relative error is shown in Fig. 14. 



Wj is shown as an example. 



2. ON THE EVALUATION OF THE IMPULSE 

 RESPONSE FUNCTION 



The impulse response function is one of the forms by which the character 

 of the response of a linear system is expressed completely. This has long been 

 used very conveniently in many engineering fields. However, it has been rather 

 unfamiliar to naval architects. Fuchs and MacCammy [9] wrote a paper in 1953 

 and made it clear that the time history of the heave and pitch can be synthesized 

 by the convolution of impulse response and the time history of the waves. They 

 computed the impulse response function theoretically for a cylinder, and as the 

 Fourier inversion of the frequency response function obtained from tank experi- 

 ments for a ship form. The present author [10] has already called attention 



111 



