A comprehensive grasp of vessel manoeuvring characteristics is indispensable for ensuring precise handling and maritime safety. In practice, for Masters and Pilots, an intuitive understanding of the ship's rotational centre—the pivot point—is often more critical than merely fulfilling performance metrics. This study systematically investigated the dynamic migration of the pivot point for a KCS vessel under various wave conditions (initial direction, length, and height), addressing a topic relatively overlooked in conventional manoeuvring studies. The research methodology employed a high-fidelity URANS approach combined with a dynamic overset grid method to simulate 6-DOF turning circle manoeuvres. Through numerical analysis, stable pivot point behaviour under general sea conditions was confirmed, while non-linear and abrupt positional shifts under critical threshold conditions were quantitatively identified. Notably, the results numerically demonstrated that the pivot point migrated sharply beyond the bow boundary under extreme wave heights or when encountering short waves in quartering sea. This finding confirms that the pivot point is dynamically repositioned by changes in hydrodynamic moments driven by sway and yaw motions. These findings serve as a practical reference for operators to pre-emptively recognize and respond to changes in rudder effectiveness and turning moments when manoeuvring in adverse weather conditions.