These days ship designers make efforts to improve the ship propulsive performance in actual seas. To reduce added resistance due to waves the bow shape above water is important factor. Some ships install the bolsters at the bow, however, it is thought that waves acting on the bolsters affect the propulsive performance in actual seas. Thus tank tests in waves using a model ship with two types of the bolsters and without bolsters were carried out and the influence of bolsters on the propulsive performance was examined.

As a result, it is found that the increment of added resistance in waves is not so large since the bolster interfered with the waves reflected by the hull.