CORRELOGRAM 
ERMIR EEA 
Sey 
-1.0 
Fig. 3.8. Auto correlation of waves, roll, and cross correlation of 
wave-—foll of a model ship (shift 7 = 9). 
(From Yamanouchi.?2) 
IMPULSE RESPONSE 0.1 
FROM Ryz(t) = A(t) * Axx(t) 
> : CONVOLUTION 0.05 
Fig. 3.9. Impulse response of roll to wave height (without advance speed). 
(From Yamanouchi.?) 
output is analyzed as the response to a single definite input. This approach is reasonable 
when the real source of excitation for the system is actually single and no other source 
need be considered, even if several outputs are correlated or combined. For example, 
even though the sway, roll and yaw, or pitch, heave and surge motions of a ship are 
75 
UNDERSTANDING AND PREDICTION OF SHIP MOTIONS 
