After the characters of the ship oscillations among waves were discussed in Part I of this paper, the general aspects of the ship oscillations among irregular waves as a stochastic process were investigated here. The theoretical basis for the analysis of the stochastic process is already clear, however there are quite a few problems in numerical computations of the sample spectrum function, although that is used usually as the most convenient function to express the response to an irregular input.
The author tried to make clear the problems and improve the process in applying the method to the analysis of ship oscillations. After trying to make clear the limitations and defects of the spectrum analysis, the author discussed the character and the usefulness of the correlation functions of ship oscillations, which is not usually used being considered to be inferior to the spectrum in few points, and which the author still believes to be more informative to express the response, and is more convenient to be handled in some cases, rather than the spectra.