Investigation of Tug Boats' Behavior during Ships' Berthing and Unberthing

The law and training system of pilotage have been changed since 2007 in Japan, and third grade pilots' education have been started from next year. The pilots had no on-board experience, so the pilots did not have the skill and knowledge to use tug boats. The pilots are studying how to use the tug boats by ship handling simulation. When a pilot commands a ship for berthing and unberthing by the tug boats' supporting, time lags and the action time of the tug boat occur and are changed with ships' gross tonnage, speed and etc. Usually the time lags between the actions and the answers break out by a tug boat captain's decisions. In this paper, the authors investigate the action time and the time lag between the action and the answer of the tug boat, when supporting for berthing and unberthing. If the pilots have knowledge about the time lag, they can order safely to tug boats at the appropriate time.