Regarding the added resistance in waves, research on head waves was mainly performed for a long time, mainly because of the restrictions of test facility which allows only test in head waves, and also it has been considered that heaving and pitching motion seems to be dominant and the influence of lateral motion is relatively small. Recently, Valanto and Hong ⁶⁾ reported that each motion of six degrees affect great on added resistance in oblique waves based on the test results. Therefore, it seems necessary to investigate the influence of ship motion of 6 degrees of freedom on the added resistance in waves again.

In this paper, measurement of ship motions and added resistance for large blunt ship in oblique and beam waves were carried out and experimentally showed that rolling motion has a very large influence on the resistance increase in waves in the vicinity of its natural period. In addition, qualitative consideration will be given to the mechanism that the added resistance in the beam wave increases by the influence of the rolling motion.