STEERING SYSTEM HAVING FUNCTION OF CORRECTING STEERING ANGLE OF UNIAXIAL TWO-RUDDER VESSEL

A digital twin computation section 291 collects a speed of an own ship, a position of the own ship, and a heading of the own ship in real time, and reproduces an actual hull motion of the own ship realized at a current steering angle on a navigational electronic marine chart. A simulation computation section 292 displays, on the navigational electronic marine chart, an assumed hull motion of the own ship determined by calculation that assumes that a force acting on the hull is a driving force at the current steering angle. A resultant force of external forces computation section 293 calculates an acting direction and a magnitude of a resultant force of external forces acting on the hull based on a ship speed difference, ship position difference, and heading difference between the actual hull motion and the assumed hull motion. A specified rudder angle computation section 294 calculates a corrective rudder angle for resisting the resultant force of external forces, and calculates an appropriate steering angle by correcting the current steering angle with the corrective rudder angle.