Estimation of Ocean Wave Characteristics and Improvements of Ship Performance of Coastal Cargo Ship

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Model experiments in waves and full-scale measurements on the coastal cargo ship have been conducted and the following conclusions are obtained:1) The estimation method for the wave characteristics has been proposed and the capability of this approach has been confirmed by comparing the significant wave heights, average wave periods and wave directions obtained from the encounter waves measured on the towing carriage, with the ones from the direct measurement of waves in the experimental tank.2) When the estimated values obtained from the ship motions in waves are compared with the direct measurement of waves in the experimental tank, it was found that the average wave periods give comparably good results, the significant wave heights are different in the following waves and the wave directions has an accuracy of 70〜80% in. the range of 30 degree.3) The distribution of acceleration in the cargo hold can be estimated from the measured data of ship responses in the bridge of the coastal cargo ship "Yusho-Maru"(Length 76m, Breadth 12m).4) The practical method for estimating the amount of shipping water into the hold over the hatch coamings of a hatch coverless container ship, which has a large deck area from the bow to the location of hatch coaming, is proposed by combining the "dam breaking theory" and "wave overtopping theory" with "flood waves theory".5) Regarding the safe and scheduled operation of the ship, the relations between the occurence of shipping water and operational conditions (ship course and speed) has been investigated and the operation diagram for the master to prevent shipping water has been shown.