Abstract
A free-run experiment of a VLCC model ship was carried out in short regular waves. The wave length and the heading angle were varied in range of 0.2≤λ/L≤1.5 and 0°≤χ≤180° respectively. The ship motion, vertical & lateral bending moment at midship, relative water level and wave pressure were measured. Among them, wave pressure on the side wall near the load water line was the particular interest of this experiment.
The first harmonics of the measured data were plotted with calculations of the strip method. We tried two strip methods to compare the accuracy. The first one is so called new strip method “NSM” and the second one is improved NSM we have developed. The solution method for the diffraction problem is improved to satisfy the exact body surface boundary condition. The plots of the measured wave pressure with the calculated value show that the accuracy of NSM is poor when λ/L≤0.5. On the other hand, the accuracy of the improved NSM is still good even when λ/L=0.2.
Another difficulty for the estimation of wave pressure amplitude near the load water line comes from the exposure of wall in the air. This phenomenon is essentially non-liner. However, we found a very simple mehod to correct the pressure given by NSM. This method is based on the experimental fact that quasistatic pressuure, which is identical to the static pressure measured from water surface, can be substituted for the wave pressure near the load water line.
