Course control system for marine vessel, and marine vessel

A marine vessel comprising:

• a propeller that provides propulsive force to the marine vessel;
• and
• a course control system including:
• a course changing mechanism that changes a course of the marine vessel;
• and
• a controller configured or programmed to:
• detect a sudden movement of the marine vessel originating from broaching caused by a following wave of the marine vessel in a case where
• an actual yaw rate at a time when the marine vessel turns its head is greater than a yaw rate estimated from an amount of operation by a vessel operator, and
• the marine vessel changed its course in a direction in which the marine vessel is to encounter the following wave, and
• upon detecting the sudden movement of the marine vessel originating from the broaching, control a rotation rate of the propeller and/or cause the course changing mechanism to change the course of the marine vessel.

A course control system for a marine vessel, comprising:

• a controller configured or programmed to:
• judges that preconditions of occurrence of a broaching are satisfied in a case where
• a wavelength of a following wave is 0.6 to 2.3 times as long as a length between perpendiculars of the marine vessel, and
• a condition that a wave height of the following wave is equal to or greater than 0.04 times as long as the length between the perpendiculars is satisfied.