Abstract
In the current literature on seaworthiness, it is generally assumed that the pitching and heaving motions of a ship in longitudinal regular waves can be described with sufficient accuracy by a set of two coupled linear differential equations of the second order with constant coefficients.
Using a model, performing forced oscillations in still water, the coefficients of these differential equations are determined experimentally for an 8 ft. model of the Sixty series with a blockcoefficient of .60. The exciting forces and moments are measured on the restrained model in waves.
Four modelspeeds and a wide frequency range are considered.
The solutions of the differential equations, determined in this manner, are compared with the measured motions of the same model in regular waves.
A good agreement is found between the computed and measured modelmotions.
It is shown that some of the so called coupling terms, have an important influence on amplitude and phase of the model motions.
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