Efficient Coupling of Slender Ship Theory and Modular Maneuvering Model to Estimate the Ship Turning Motion inWaves

摘要

Turning tests in waves are simulated by the coupling between slendershiptheory and modular maneuvering model in the framework of twotimescale method. At each time step, the second-order horizontal steadyforces and yaw moment are estimated by the far-field method utilizingthe Kochin function as a function of incident-wave frequency and amplitude,relative heading angle between incident wave and ship, and forwardspeed, and their magnitudes are added as the wave effect in the maneuveringmotion equations. Accordingly, the maneuvering-motion simulationprovides the instantaneous forward speed of a ship and the heading angleto the seakeeping analysis. In order to keep the accuracy of the simulationmodel, calm water hull derivatives are taken from the captive tests.A comparison between simulations and measurements indicates the practicalreliability of the proposed model. Improvement in the estimation ofwave-induced steady forces and yaw moment is crucial, particularly inshort waves, while the model provides better estimation in longer waves.Sensitivity study in short waves also implies that the steady sway forceis the largest contributor to the phenomenon that the ship drifts to thedirection of incident waves.