甲板冠水持続時間の推定に基づく乾舷規則の評価

抄録

This study deals with the influences of probability density distribution of exceeding lasting-time on deck wetness for ocean-going ships. Using the envelope theory for the random functions, a general formula for approximation calculation of density function between zero level is induced and expanded to the problems above a given non-zero level. A supplementary algorithm of estimating the time lasting period for deck wetness is also induced in this paper. Comparing results in the distribution range between the 1^st quarter number and 3^rd quarter number of probability density, the reliability of the proposed method to estimating the deck wetness for ocean-going ships is also confirmed. Based on wave statistics data, GWS, the deck wetness related to freeboard sea zones of ILLC 1966 is appraised by discussing exceeding lasting-time during which the amplitude of relative motion between deck and wave surface remains above a level of freeboard. A series of numerical calculations are executed for an ocean-going container ship based on the 5 freedom ship motions theory (the Ordinary Strip Method, OSM), and it is certified that the lasting time affects the trend of deck wetness.