On the Hydrodynamical Forces Acting on Box Type Vessels and Their Motions : 1st Report : On the Forced Oscillation Test

Abstract

It seems that a standard calculation method of motions of box type vessels testified by experimental data has not been definitely established yet. Therefore, as a means to estimate the hydrodynamical forces acting on the box type vessels and their motions, the authors have manufactured a forced oscillator and carried out a forced oscillation test and wave induced force test so as to obtain various coefficients for the equations of the motions and wave induced forces. This paper presents the forced oscillator and a part of the results of the tests conducted. The results of the tests have been arranged to correspond to those of the theoretical calculations by two-dimensional source distribution method, by which it has been found that the test results and the theoretical calculation results mostly agree with each other except the damping moment coefficient of roll. However, in such box type vessels as having a large B/d and a large shallow water effect, differences have been found between both results. Thus, it has been made clear that the test method using the forced oscillator is a good means to solve the problems of shallow water effect, three-dimensional problem, etc. which the box type vessels have and also useful and helpful for improvement of the accuracy of the theoretical calculation.