Initial and Steady Turning Characteristics of KRISO Container Ship (KCS) in Regular Waves

Abstract

It is necessary to analyze the ship’s manoeuvring performance in waves at early design stage for the safe operation. In this study, turning characteristics of KRISO container ship (KCS) were investigated by free-running model tests in waves. 35 degree turning circle tests in regular waves were carried out in KRISO Ocean Engineering Basin with the variations of regular wave conditions such as wave heights, lengths, and directions. Wave heights were varied from 0.01 to 0.02 L, lengths were 0.5 to 1.2 L, and directions were 150 to 270 degrees. In all the tests propeller revolution rate (RPS) was fixed as the constant values corresponding to the full-scale speed of 16 knots in calm water, rudder was deflected at the moment when the wave crests pass the model midship. Ship’s turning behaviours in waves can be divided into two stages such as initial transient motions and steady turns. Initial turn abilities for emergent collision avoidance, and trajectory drifts in steady turns were obtained from the present model tests, and the effect of wave conditions on the turning characteristics were investigated. New index which represents hard-over initial turning ability for collision avoidance in waves is proposed by using advance and transfer. The relations between initial turning characteristics and steady turn drifting angles are discussed.