PURPOSE: To sail the ship on the most proper cource by a method wherein an automatic steering mechanism is controlled so as to change the course properly in accordance with a wind direction close to an algorithm based on a predetermined course determining method.

CONSTITUTION: An objective bearing information transmitted from a base on the ground is received with a receiver 2 and is transmitted into an operating section 6. The wind direction on the sea on which the sailing ship is located is sensed by a wind direction sensing section 3 and a wind direction information corrected by a correcting section 4 is supplied to the operating section 6 sequentially. Further, an own bearing sensing section 5 senses the bearing of the sailing ship and supplies the own bearing information to the operating section 6 by an by. The operating process is effected by the algorithm based on the predetermined sailing course determining method being memorized in the memory of the operating section 6 to make a decision whether the objective bearing is a sailable bearing or not. When it is decided that the bearing is sailable, a course controlling information in accordance with a difference between the present own bearing and the objective bearing is supplied to the automatic steering controlling section 8. When the objective bearing is decided that it is not sailable, the course controlling information in accordance with the above-described algorithm is supplied to the controlling section 8.