单项选择题 The distance a vessel moves parallel to the original course from the point where the rudder is put over to any point on the turning circle is called the（）.

单项选择题 The distance a vessel moves at right angles to the original course，when a turn of 180°has been completed，is called the（）.

单项选择题 The best method to secure a towline to bitts is to（）.