EXPERIMENTAL STUDY ON KCS CONTAINER SHIP INITIAL TURNING AT LOW SPEED IN REGULAR WAVES

Since the Energy Efficiency Design Index EEDI was introduced by International Maritime Organization IMO, an increasing attention to the ship's controllability in waves, in particular at low speed is observed. One of the main reasons for this is the fact that, in order to satisfy the EEDI requirements, there is a tendency to reduce the power consumption and the propellers RPM reduction while maintaining existing control means, which results in reduced ship steerability mainly at low speed. This study considers the effect of regular sea waves on ship’s initial turning parameters at the set of service conditions. By means of free running model tests the influence of low advance speed on course and maneuvering trajectory changes in transient turning motion were investigated. The effects of the wave encounter angle variations were examined during the tests, including application of different wave lengths. Using the experimental results, an attempt was made to normalize the ship's handling in adverse sea conditions by applying a simple criterion based on the initial time to reach a given course. The results of the present study can be used for benchmarking of numerical simulations of low speed maneuvers in regular waves.