Description of Ship Form and Evaluation of Ship Performance

Abstract

Ship form has been expressed using the “OFF-SETS” and “PRINCIPAL PARTICULARS (PRINCIPAL DIMENSIONS)” with “LINES” for about 100 years since the beginning of the modern developments of ship engineering/science.In the field of ship design, ship performance has been estimated and evaluated by means of indirect parameters such as principal dimensions and coefficients. Since these parameters do not give an unique ship form, ship designer has utilize their experience and intuition during the procedure of performance design for improving and determining the ship form. However, how long are we able to pass on the skilful knowledge to the future generation ?In the present paper, the authors propose a method for describing ship form by means of Fourier series called Fourier Descriptors (FD). They will show that FD can determine an arbitrary ship section uniquely and can decompose/reproduce arbitrary 2-dimensional ship section form.As the 1 st step of the performance evaluation, they show the effects of section form on the damping and added mass coefficients of 2-dimensional oscillating bodies that are commonly used in the ship motion estimation with comparing results obtained by means of Lewis Form transformation.