Inverse Estimation of a Current by Using Ship Motions⁎⁎This work was supported by JSPS KAKENHI Grant Number JP26560196 and JP17K06978.

A newly built ship must conduct sea trial to understand its performance including speed, maneuverability and so on. The result of the speed trial is very important for the ship owner, because the ship speed is directly related to profit. In this case, current becomes an important factor because the ship speed is changed by the effect of the current. To remove this effect, International Towing Tank Committee and International Organization for Standardization heve presented procedures of removing this effect. However, these procedures require two or three round–trips against one ship speed. To solve this difficulty, we attempt to estimate herein the current from the ship motion based on successive data assimilation. The proposed method is verified by twin experiments. Consequently, the proposed method is found to estimate the current well.