On the Hydrodynamic Forces on High Speed Ship Oscillating in Sway and Yaw

Abstract

The strip method is in common use for predicting the hydrodynamic forces on ships oscillating in sway and yaw motions. However, as well known, it breaks down in the high-speed regime. On the other hand, Chapman's numerical method is known as a powerful method, but it is not applicable to bodies of arbitrary shape. Therefore it is essential to establish the new procedure which can be applied to ships of general shape and can also account for the forward-speed effect correctly in the high-speed range. In this paper a theoretical method using Fourier transform technique is presented. This method is considered to be an extension of Chapman's method, and the relationship of this method to the strip method can be shown analytically. Computational results are presented for uniform slender bodies with the cross section of general shape. The influences of the cross-sectional forms on the hydrodynamic sway force and yaw moment are investigated. Furthermore, the relations between the forward-speed effect and the cross-sectional forms are also discussed.