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Considering the sea conditions in which a large ship encountered in operation, the ship’s behavior in very short waves is important. However, the evaluation of the ship performance in very short waves was not enough validated by tank tests. Because it is difficult to generate waves with enough accuracy due to the performance of the wave generator. In this paper, it is shown that tank tests of added resistance in the regular waves including the very short waves are conducted in the Actual Sea Model Basin at National Maritime Research Institute, MPAT for DTC container ship and accurate results are obtained. The test results are compared with the benchmarks published by SHOPERA (Energy Efficient Safe SHip OPERAtion). In addition, three curves of the added resistance in the regular waves based on the results of the tank test are compared and the sensitivity analysis of energy efficiency is discussed. In the sensitivity analysis, the performance simulator for ships in actual seas (VESTA) is used, and a comparison is carried out for the fuel consumption calculated from the frequency response of each added resistance in waves. As a result, it is found that the tendency in added resistance in very short waves affects the fuel consumption and the decrease of ship speed.

SummaryIn order to reduce greenhouse gas (GHG) from shipping sector, it is necessary not only to build eco-friendly ships but also make some efforts for reduction of GHG from ships in service. In this regard, especially for fine ships such as a vehicle carrier and a container ship, it is well known that ship propulsive performance can be enhanced by trim optimization, which can contribute to environmental protection and can bring ship operator economic benefit due to fuel saving.This study addresses trim optimization for propulsive performance by the means of model tests. Model tests are conducted for various trim conditions and the required power is estimated for consideration of trim effect in still water. The effect of draft and trim variation on propulsive performance is investigated and the trim condition in which required power can be saved is clarified.

SummaryWhen a ship is carried out speed/power trials in shallow water, the measured power is larger than that in deep water. To correct the effect the method is recommended by ITTC and standardized by ISO.In ITTC a method by Raven, which corrects viscous resistance considering the squat effect is proposed to alter the method by Lackenby which corrects the speed.In order to evaluate the shallow water performance, resistance and propulsion tests were carried out using a tank which can perform the tests in both deep and shallow waters. The engine power estimated by the results of the tank tests, Lackenby method and Raven method have been compared and evaluated.From the evaluation it is clarified that Raven method shows lower engine power than Lackenby method and can be applied for the shallow water correction by means of conservative correction.