Thirdly , the basic configuration plan of a ship undocking assisted by different number of tugs is given . the relationships among the gyroidal moment , gyroidal time and drag forces of tugs in the process of ship undocking are analyzed . the margin of the tugs " towing forces during the ship undocking and turning process is studied 三、制定了不同數(shù)量拖輪協(xié)助船舶出塢時的基本布置形式,給出了不同拖輪協(xié)助船舶出塢時的拖輪布置示意圖,并試驗(yàn)分析了船舶出塢回轉(zhuǎn)力矩與回轉(zhuǎn)時間和拖輪拖力之間關(guān)系,并確定了用于船舶出塢回轉(zhuǎn)的拖輪拖力的余度大小。