System and method for estimating center of movement of marine vessel

In the present invention, a provisional center (g1, g2) of movement is set to a predetermined position in the vicinity of the actual center (G) of movement of a marine vessel (2), outboard motors (3a, 3b) are driven, imparting a test thrust (P) having a predetermined magnitude and direction to the provisional center (g1, g2) of movement, the direction and magnitude of the angular acceleration arising at the marine vessel (2) by means of imparting the test thrust (P) are detected, the magnitude of the angular acceleration is compared to a predetermined threshold, and when the angular acceleration is greater than the threshold, the provisional center (g2, g3) of movement is altered and set in a manner so as to converge with the threshold.