Abstract Authors continued to develop and expand new experimental methodology on tank model test with the MDES (Marine Diesel Engine Simulator) and the ATS (Auxiliary Thruster System), for making evaluation techniques on actual ship performance in waves more sophisticated. In this fourth report, the methodology is so enhanced that measured results of model test can be directly evaluated as the actual ship performance in waves. Here, the details of the newly expanded methodology are introduced, and experimental results measured from the free running model tests in waves with the expanded methodology are validated, even focusing on behaviors of ship diesel engine.

Abstract The experimental methodology for Self-Propulsion test with a MDES (Marine Diesel Engine Simulator) is expanded by a newly developed Auxiliary Thruster System. The MDES controls propeller rotational speed, by measured propeller torque and rotational speed itself as inputs, with control algorithm reflecting the marine diesel engine characteristics. Here, with auxiliary and adjustable force equaling to Skin Friction Correction on a model ship even in free running experiment, we can make propeller loading condition of model ship corresponded to that of actual ship at same Froude number. Authors developed an Auxiliary Thruster System (hereafter, ATS) whose thrust force is controllable. Then, adding the force equaling to Skin Friction Correction by the ATS, the experimental methodology with the MDES will be upgraded, because propeller torque input to the MDES are greatly approached to that corresponding in actual ship. In this study, free running model experiment in waves using the MDES and ATS were conducted, and there are significant differences between the results with and without the ATS. Furthermore, a problem on the methodology with the MDES and ATS are discussed.

ABSTRACT This paper introduces the development of marine diesel engine simulator and proposes a new experimental methodology for self-propulsion test in waves. A marine diesel engine simulator is developed for self-propulsion test of a model ship. This is composed of a servomotor, speed controller, dynamometer and PC. On the PC, marine diesel engine simulation program is installed. Based on a mathematical modeling of the engine, this program simulates fuel supply control by governor, torque generation by combustion and shafting system rotation. Inputs are rotating speed and propeller torque measured by dynamometer, and output is target speed to the speed controller of the servomotor. This is a real-time control system of propeller rotating speed, which reflects the characteristics of marine diesel engine. Using this system, the authors conducted self-propulsion test of a model ship in waves and checked system operation capabilities. We can measure not only ship motion responses but also the realistic dynamic responses of ship propulsion system in waves such as propeller load and rotating speed fluctuation, fuel supply rate and et cetera. INTRODUCTION Performance of ships is customarily evaluated in the calm sea even though ships are operated in wind and waves. This is due to the absence of practical technology to guarantee ship performance in the actual sea condition. Accordingly, contractees have no choice to accept the result of sea trial based on this business practice. This situation is hardly improved in these decades. However, to meet the recent requirement of energy saving and CO 2 emission reduction, it is craved to develop new technologies to estimate real performance of ships in the actual sea condition. Needless to say, ship performance in calm sea condition, "calm sea performance", is the base of that in actual sea condition, "actual sea performance". Now, let us briefly review the estimation method of the calm sea performance in design stage. Following procedures are commonly used.

ABSTRACT: Course stability is one of important factors of ship maneouvrability. Recently, in order to improve of ship propulsion performance, the buttock flow hull form has often been used. However it is well known that ships with buttock flow stern tend to have inferior course stability. So in order to improve course stability, ships with buttock flow stern are often equipped with stern skeg. Effects of stern skeg on course stability are not always clear, it still worth considering. We studied about interaction between hull and stern skeg such as ratio of additional lateral force induced by stern skeg and the distance between the center of gravity of ship and the center of additional lateral force. INTRODUCTION In order to reduce a Green House Gas, ship propulsion performance needs to be improved. From point of it buttock flow stern is one of the good answers. But it is well known that ships with buttock flow stern tend to have inferior course stability. The other hands, to equip with stern skeg it is improve course stability. So it is important to estimate effects of stern skeg on course stability. In this paper, effects of stern skeg on course stability about ship with buttock flow stern with it (Single skeg : S1, Twin skeg : S2) and without it (No skeg : S0) are investigated. And we simulated flow fields around model ships in oblique motion and circular motion test (CMT) by use of SURF code (Solution algorithm for Unstructured RaNS with Finite volume methods) which was developed by Hino et al. at NMRI and compared with results of model tests. We validated this code in manoeuvring motions and studied about interaction between hull and stern skeg such as ratio of additional lateral force induced by stern skeg.

Container ships operate with large number of unit containers on the deck, and then they have many kinds of external ship forms due to the position of them depending on need for delivery demands. In the operation of the ships, wind load mostly works as resistance. The estimation of wind effect has important role for calculation of economical cost for operation. There is, however, no simple method to calculate the wind load for those container ships with crested or lacked containers without carrying out wind tunnel experiments. In this paper, ease estimation method for wind load on such kinds of container ships is proposed using experimental investigations. INTRODUCTION Large-scale container ships, which have 6000TEU more over containers onboard and 300m length over, are built one after another recently. A large container structure above sea level is largely affected from wind at sea. Assessing navigational performance of the ships, it is important to estimate wind effect exactly. Ordinary, specification of a ship external form in case of a tanker, a bulker, a PCC etc. doesn't change excluding the main hull's thickness that means the height from sea level to main hull deck top. The estimation methods of wind load often used basically target fully loaded or ballast ships' condition (Yamano, T and Saito, Y, 1970; Isherwood, 1972; Fujiwara et al., 2005a, 2005b, 2006 etc.). On the other hand, container ships have many kinds of ondeck forms depended on the number of containers. Under these situations, it is difficult to reflect individual shape influence on the deck of the ships in the estimation methods, since the methods on the basis of regression analysis are basically proposed using fully loaded or ballast ships' experimental results and only use some simple ship external form parameters, that is, lateral projected area, center potion of the projected area above sea etc. for calculation.