The research vessel NARA equipped with an azimuth thruster system was built in 2015. There are few vessels with this propulsion system in Korea. This vessel has two modes such as the normal for maneuvering and the power for investigation, and the other two modes as one axis and two axes on the operating. This type of vessels does not seem to have a clear grasp of the maneuvering character in comparison with the vessel with a conventional propulsion system. So the authors carried out the sea test for the turning, the zigzag and the inclination, and the results are as follows. In turning test, the case of using the two axes mode is much better than the case of using the one axis mode for the elements of turning, such as advance, transfer, tactical diameter and final diameter, but turning hard over the rudder in full speed is very vulnerable to capsize in both modes. In zigzag test, the yaw quicking responsibility index,  is very large excessively, which means a bad counter maneuvering ability, so an operator has to keep in mind that in turning operation. If necessary to avoid collision at head on situation, it may be a more effective method to use the crash astern stop than the turning according to the conditions and circumstances for the shortest stopping distance is very short.

콴다 효과를 이용한 고 양력 타가 선박의 조종성능에 미치는 영향을 평가하기 위하여 모형선 선회 시험을 수행하였다. 대상선은 47K PC선이며 1/85 스케일의 2m급 모형선을 이용하였다. 모형선 선회시험시스템은 모형선, 콴다 타, Jet 분사 시스템 및 타 구동장치 등으로 구성된 다. 모형선 선회 시험 결과, 고 양력타에 의한 타력 증가가 선박의 선회성능 향상에 효과적인 것을 확인하였다.

예선이 부선을 선미예인하고 있는 상황에서의 예부선 조종특성을 확인하기 위하여, 예선 단독 실선시운전과 예부선 통합 실선시운전 시험을 수행하였다. 속력시험, 가감속시험, 10도 선회시험, 20도 선회시험, 10도 지그재그시험, 20도 지그재그시험을 통하여 다양한 상황에서의 예선과 부선의 운항 특성을 확인하였다. 그 결과, 부선이 선미예인되는 경우, 예선의 전술선회직경은 예선 단독운항일 때보다 증가하며, 선수동요각 변화율이 낮음을 확인하였고, 침로 변경을 함에 있어 부선의 선수동요각 변화가 늦고, 오버슈트각이 큰 것을 확인하였다. 또한 선회나 침로 변경 시, 부선의 선회궤적이 예선의 선회궤적 안쪽에도 존재할 수 있음을 확인하였다. 따라서 부선을 선미예인하는 운항자는, 선회 및 침로변경 시 예부선의 선회궤적, 예부선의 선수동요각 변화시간 및 오버슈트각이 증가하는 것을 충분히 인지하고 운항해야 할 것으로 판단된다.

The objective of this paper is to make clear the difference of maneuvering characteristics of a VLCC in standstill from those of her in running. The authors made mathematic models to calculate maneuvering motions of a VLCC in standstill using various ahead engine with full rudder angle and calculated their motions in each case and compared the calculated values with those of the same vessel running in sea trial tests. The difference of motions between them is great. For example, a VLCC in standstill can achieve a great alteration of heading over 90 degrees within the distance of 0.2L advance while she advances 3.0L for 90 degrees turning in full running sea trial turning test. Therefore whenever a VLCC in standstill meets a vessel approaching in collision course situation in near distance, it is better and recommendable that she should use her ahead engine with full rudder to avoid collision. So "maneuvering trial tests in standstill conditions" should be added to the content of sea trial tests when a newly built VLCC commence to take sea trials, that has not been included until now.