수조 실험에 의한 게 통발 어선의 복원성에 관한 연구

Abstract

본 연구는 우리나라 연근해에서 조업하고 있는 게 통발어선의 횡파중 복원성 특성을 파악하고자 모형선을 이용하여 수조실험을 수행하고, 배수량의 변화, 파고, 파주기, 그리고 풍속의 변화에 따른 횡동요 특성을 분석하였다. 또한 횡동요 운동방정식에 의한 수치 계산의 결과와 복원성 특성을 도출하고, IMO 복원성 기준과도 비교하였다. 게 통발 모형선의 실험 결과를 요약하면 다음과 같다. 1. 횡동요는 배수량과 파주기에 가장 큰 영향을 받으며, 그 크기는 배수량에 비례하고, 파의 주기에 반비례하는 현상을 나타내었다. 2. 전체적으로 파고의 크기는 횡동요를 증대시켰지만, 파주기의 어떤 특정 영역내에서는 횡동요를 증가시키지 못하였다. 3. 정상풍에 의한 풍속은 횡동요에 크게 영향을 미치지 않는다. 4. 선박의 횡동요는 배수량, 파주기, 파고 그리고 풍속 등을 종합적으로 고려해야 보다 정확한 분석을 할 수 있다고 판단된다. 5. 모형선의 초기 횡메타센타높이는 0.48m이며, 복원력 소실각(φr)은 81.5˚, 위험경사각은 40.8˚, 그리고 최대 복원정(GZ_(max))은 경사각 32˚에서 0.19m임을 알 수 있었다. 6. 모형선은 IMO의 어선 복원성규정 및 국내 어선 복원성 기준을 만족하고 있다. 그러나 횡경사각이 32˚를 초과하면 전복의 위험이 매우 크다고 판단된다.

Marine casualties of vessel are serious problems on social and national aspects, because the results of it come to an end of the sacrifice of lives, a great lose of properties and marine pollution. According to the recent statistics of marine casualties in Korea, fishing boats are more likely to be ended in the casualties, and small fishing boats especially cause much more accidents in sinking and capsizing than any other big vessels. These casualties were mainly produced from the ignorance on the lack of own ship stability. The fact is very severe problem to the small fishing boats which are operating at adjacent area including the crab trap fishing boat. From these point of view, this study aims to analyze the characteristics of stability on the crab trap fishing boat receiving transverse wave by means of carrying out the water tank test. The author measured the roll angle of the model ship by using the experimental measuring system. The data from the experiment was provided and analyzed to investigate the rolling characteristics of the model ship being affected by the change of displacement, wave height, wave period and the wind speed. And in order to compare the rolling characteristics of the model ship with the international stability criteria, the rolling motion of it was investigated numerically. And then the stability characteristics of it were evaluated by qualitative and quantitative analysis on both side. The results of the characteristics of stability on the model ship are summarized as follows. 1. The rolling angle of the model ship was affected largely with the displacement and the wave period of it, and the trends were shown that the magnitude of the angle was proportional to the displacement, but inversely to the wave period. 2. In general, the increase of the wave height made the rolling angle bigger, but it had effect on the rolling angle in the specific range of the wave period. 3. The force of steady wind didn't have influence on the rolling variation significantly. 4. When analyzing the rolling characteristics of a small fishing boat, it needs to consider the displacement, wave period, wave height and the wind speed comprehensively to understand the mechanism implied accurately. 5. It was found out that the initial metacentric height, the angle of vanishing stability, the substantial range of stability and the maximum GZ of the model ship were 0.48m, 81.5˚, 40.8˚ and 0.19m respectively. 6. The stability of the model ship was satisfied with the rule of IMO and the domestic of stability.