선미트롤어선의 운항 형태에 따른 거동 특성

Abstract

Fishing vessels occupied about 70% or more of the total casualties according to the marine accident statistics in the last 10 years in Korea. Dragging fishing vessels such as the stern trawler and the drag boat occupied about 25% of the casualties of capsizing and sinking in the statistics. The main factors of the casualties by those fishing vessels are based on the wave and wind mostly, but if look into the factors more strictly, the causes arrive at the human factor that the fish men concentrate the catching job entirely in the fishing ground without grasping the sea keeping quality of own ship certainly. But it is very important to investigate the hull response of a fishing vessel in rough seas for ensuring the safe navigation, fishing operation and preserving the excellent sea keeping qualities. For this purpose, author measured rolling and pitching responses of the vessel in waves using real sea experimental measuring system. In real sea experiments, the stern trawler, Kaya(1,737GT), training vessel of Pukyong national university was used. The experiments were carried out in the adjacent waters off Korea during the cadets on board training times. The author analyzed the experimental data using statistical and spectral analyzing method to get the characteristics of the motion responses of her according to the state of its operation. The results were summarized as follows ; (1) In drifting situation, the significant and the maximum values of rolling were increased according to the wave height, but those of pitching were decreased. In addition, the response and the period of peak of rolling motion due to the wave height were increased, but those of pitching were decreased. (2) In navigation situation, the significant and maximum values of rolling were increased according to the wave height, but those of pitching were little changed. In addition, the response of rolling motion had the highest in the quartering sea, and then beam sea, following sea, bow sea and head sea in the order, the response of pitching motion was the highest in the bow and the head sea, and then beam sea, following sea, quartering and beam sea in the order in all wave height. The period of peak of rolling motions due to the wave height and wave direction were a little changed as the seconds of 3.8∼9.9, and those of pitching motions were also little changed as the seconds of 3.3∼10.4. (3) In trawling situation, the significant and maximum values of rolling were a little increased according to the wave height, but those of pitching were much increased. In addition, the response of rolling motion was highest in beam sea, and then bow sea, quartering sea, head sea and following sea in the order, the response of pitching motion was highest in head sea, and then following sea, beam sea, quartering sea and bow sea in the order in both waves height. The period of peak of rolling motions due to the wave height and wave direction were a little changed as the seconds of 6.6∼10.9, and those of pitching motions were also a little changed as the seconds of 6.7∼11.2. (4) Comparing the flutter characteristics at navigation situation with at trawling situation, it occur maximum values of rolling and the response of rolling from quartering sea at navigation situation, but those of maximum values of pitching and the response of pitching from beam sea at trawling situation. Bandwidth of the response of rolling to peak was narrow at navigation situation, but it was broader at trawling situation. Meanwhile it occur maximum values of pitching and the response of pitching from bow sea at navigation situation, but those of maximum values of pitching and the response of pitching from head sea at trawling situation. Both generally bandwidth of the response of pitching to peak was broader. The results of the study, there were some differences between the response and the period of peak and the bandwidth from navigation situation and trawling situation. Therefore, operator have to handle vessel by considering these facts, and it will be necessary that a study to be made more to extract the general trend of the characteristics on the response of the stern trawler.