Speed trial analysis method eliminating the need for external disturbance data

ABSTRACT Ship speed performance is typically evaluated in the absence of external disturbances. Therefore, speed performance data obtained in full-scale trials are corrected to obtain speed performance with no external disturbances by eliminating disturbance effects due to wind, waves and current. This correction is called the speed trial analysis of ships. In this paper, a speed trial analysis method named as the power-based Taylor expansion method (PTEM) is presented, in which added resistance caused by an external disturbance and current velocity are not required. To verify this method, virtual speed trial data are generated theoretically for various current velocity conditions with constant wind, and the PTEM is applied to eliminate external disturbance effects from virtual speed trial data. Correction results are compared with known true results. The correction accuracy using the PTEM is sufficient even for varying current velocities with short periods. Furthermore, the PTEM is applied to the speed trial analysis of four full-scale tankers of the same hull form. The scatter of the correction results using the PTEM is smaller than that using other existing methods. The PTEM is useful as a speed trial analysis tool because it does not require external disturbance data.