Long Term Prediction Method of Shipping Water Load for Assessment of the Bow Height

Abstract

This chapter describes model test in regular and irregular waves, which was carried out to develop a long-term prediction method of shipping water load on the bow deck. Model of a tanker for Japanese domestic voyage was used. From the result of test in regular waves, the relation between shipping water load and relative water height at stem was discussed. Shipping water load is found to be proportional to the square of the water elevation over the bow top. Based on this relation, probability density function of shipping water load in short-term prediction was proposed. The proposed function shows a good agreement with the measured distribution in irregular waves, especially the tail of it, better than the conventional function. Using this prediction method, assessment of bow height of Japanese domestic ships from the viewpoint of deck wetness was carried out. The correlation between shipping water load and the exceeded height—the relative water height at stem exceeded the bow height—was seen to be strong. The probability density function of shipping water load was proposed. The method agrees well with experimental results. From the comparison with long-term prediction between present method and conventional method, it is concluded that the present method is more rational than conventional method to predict shipping water load.