No person on any Indian ship shall, when the ship is going ahead, give a helm or steering order containing the word "starboard " or "right " or any equivalent of "starboard " or "right " unless he intends that the head of the ship shall move to the "right " or give a helm or steering order containing the word "port " or "left " or any equivalent of "port " or "left " unless he intends that the head of the ship shall move to the left.