Estimation of Dynamic Frequency and Time Characteristics in Ship Motions of an Offshore Trawler

摘要

To clarify the process that leads to large-angle inclinations or even the capsizing of fishing boats, it is useful to be able to track dynamic changes in ship motions. These motions during fishing operations are not static, they change from moment tomoment according to the fishing process, and it is important to understand the characteristics of the motions during each fishing operation process. To this end, in this study we focused on conducting a wavelet analysis to simultaneously estimate the time and frequency characteristics of the motions.We conducted a wavelet analysis of motion data obtained from a160GT offshore trawler under standard running conditions and during Danish seine trawling. From the result obtained, we were able to accurately estimate motion characteristics as conditions changed during the fishing process. Periodical changes in motion were observed as a result of the resonance between the ship motions and the waves that were encountered.