• 선박안전
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• 통권22호
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• pp.34-53
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• 2007

In the case of hull material. large sized merchant ships are made of steel, on the other hand FRP or wood are used for small sized fishing boats. At present in Korea approximately 88,500 fishing boats are in operation of which 70% are made of FRP In the meantime, stainless steel is frequently used as shaft materials of the small-size FRP fishing boat. Namely, the kinds of shaft materials are STS 304(18Cr-8Ni), STS 316(18Cr-12Ni-2.5Mo steel) and STS 630(17Cr-Ni-Nb steel)etc. Among these things, STS 304 which is the cheapest and having ordinary corrosion resistance is most widely used as 2nd class shaft material. But, using STS 304 for shaft system material of the small-size FRP fishing boat on seawater environments entails a severe corrosion which causes shaft system troubles. Particularly, the corrosions tend to be concentrated of the stern and bow side, propeller shaft surface of inside of stern tube and the boat having no stern cooling pipe line system. As a solution for those problems, research on the ways to mitigate corrosion on the part of 2nd class stainless steel shaft have been undertaken. In the result, not only clarification for the reason of corrosion of the part of stainless steel shaft used mainly for the small-size FRP fishing boat was done, but also most optimal corrosion protection system was developed by experimenting shaft's protection simulation based of the electrochemical cathodic protection principle. In addition, verification through the field test on the optimal cathodic corrosion protection method by means of aluminum sacrificial anode was carried out. In this study, effective and economical shaft's protection system is suggested to the small-size FRP fishing boat operator by substantiating the results obtained from the research on the optimal cathodic protection.

• 수산해양기술연구
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• 제59권4호
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• pp.344-353
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• 2023

In the actual sea, the additional resistance due to external force such as wind, current and wave is accompanied, and the required power is added in response to these resistance. Especially when the ship is sailing at low speed, the effects of wind and current have a great impact on the safe control of the ship. Likewise, it is thought that the effects of wind and current have a great impact on the trawl ship control since the towing speed of a bottom trawl ship is a low speed of 3 to 4 knots. If the reduce of ship speed and the increase of engine power due to the influence of wind and current can be identified, the safe towing power can be calculated based on a given engine output. Thus, the appropriate size of a fishing gear can be determined. In this study, a total of 20 trawl operations were conducted for seasonal maritime research in the same research area according to the operation mode of propeller. Based on navigation data, trawl fishing data, and engine performance data acquired during the towing fishing gear, and data of ship speed, hull resistance, fishing gear resistance, wind force and current force according to an incidence angle were estimated. The overall power for these loads was calculated and compared with the measured engine power, and the effects of wind force and current force on the engine power were investigated.

• 대한조선학회논문집
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• 제34권3호
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• pp.27-37
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• 1997

본 연구는 특수타의 채택으로 인한 침로 안정성 개선 효과에 관한 내용을 담고 있다. 구체적으로 여러 특수 형태의 타(본 연구에서는 특수타로서 볼록타, 오목타, 플랩타, 엔드플레이트타를 생각함)를 동일 선체에 설치하였을 때의 침로 안정성 개선 효과를 조사하기 위해서, 먼저 특수타의 타 단독 시험을 실시하여 양력 개선 효과를 조사하였으며, 또한 선체-프로펠러-타 시스템에서의 각종 구속 모형 시험을 실시하여, 특수타가 타수직력과 관련된 실험 정수들에 미치는 영향을 조사하였다. 그리고 실험 결과로부터 특수타의 채택에 따른 조종성 미계수의 변화를 구하고, 침로 안정성을 정량적으로 분석, 비교 및 검토하였다. 그 결과, 볼록타와 오목타 그라고 플랩타는 침로 안정화에 거의 기여하지 못하고, 엔드플레이트타는 침로 안정성을 크게 향상시킨다는 것을 확인하였다. 본 연구 결과는 초기 설계 단계 또는 선박 건조 후 침로 안정성이 문제시된 선박에, 선미 형상의 설계 변경없이 타의 형상 개조만으로 침로 안정성을 개선시키고자 할 때 유용하게 활용될 것으로 기대된다.