Characteristics of Local Stresses and Wave Pressure Working on Hull Side in Seaways

Full-scale measurements of local stresses and wave pressure acting the side of a hull in a seaway were carried out on a VLCC, in an attempt to understand the actual condition of working stresses on longitudinal members and wave pressure acting near the load water line. The findings made from the study are as follows: (1) Results of the full-scale measurements showed that higher order components of wave pressure owing to wave breaking and/or impact were not remarkable. (2) The mean periods of stresses on side longitudinals were shorter than those of deck or bottom longitudinals. This comes from the difference between the response characteristics in regular waves. (3) It was confirmed by comparison with the results of full-scale measurement that the prevalent wave pressure estimation based on strip method explained the short-term characteristics of stress on longitudinals. (4) For the evaluation of local stresses of structural members where various load elements act mutually Discrete Analysis Method (DISAM for short) was found to be effective.