16. 水流航法乃向量之加減，各項速度之關係應為： (A) 本船船速(ship’s velocity)＋水流速度(velocity of current)＝實際速度(speed and course made good) (B) 本船船速(ship’s velocity)－水流速度(velocity of current)＝實際速度(speed and course made good) (C) 本船船速(ship’s velocity)＋估計水流(velocity of estimated current)＝實際速度(speed and course made good) (D) 本船船速(ship’s velocity)－估計水流(velocity of estimated current)＝行進速度(speed and course of advance)