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Ship performance in shallow water where the rigid bottom is covered by a mud layer is a crucial topic to be investigated. In such muddy areas, a two-layer fluid is stratified according to the properties of the sediments. The water-mud interface behaves similar to a sheet on which the internal waves propagate after the ship's passage. Therefore, for safe navigation, it is necessary to clearly understand the influence of the internal waves on the ship's hydrodynamic force characteristics. In this study, the steady wave-making problem of a ship in a two-layer fluid was solved using the Rankine source panel method. The boundary value problem was formulated using a newly proposed double-model linearised interface condition. After the present method was validated via a comparison with results of a Wigley hull solved by the author's existing method, it was applied to solve the ship-wave problem of KVLCC2. The unique changes in wave-making resistance, sinkage and trim according to the ship's speed and two-layer fluid conditions were evaluated. [ABSTRACT FROM AUTHOR]

Abstract  A mathematical model of a single-propeller twin-rudder ship has been developed from captive and free running model experiments. An open water rudder experiment was carried out to figure out the characteristics of the rudder. Captive experiments in a towing tank were carried out to figure out the performance of a single-propeller twin-rudder system on a large vessel. Interactions between the hull, propeller and twin rudders, including mutual interactions between the twin rudders, were expressed with several coefficients that were calculated from the experimental results at various ship speeds. In the analysis, the unique characteristics of a single-propeller twin-rudder ship, which affects rudder forces, were explained and formulated in the mathematical model. The captive model tests were conducted with zero ship’s yaw rate, so the interaction coefficients, which are influenced by the yaw rate, are determined from free running model experiments. Validation of the mathematical model of a single-propeller twin-rudder system for a blunt body ship is carried out with an independent set of free running experiments, which were not used for determining the interaction coefficients. The validated numerical model is used for carrying out simulations. Based on simulation results, some recommendations have been proposed for installing a single-propeller twin-rudder system. [ABSTRACT FROM AUTHOR]