Ship domain is crucial for traffic risk assessment and safe navigation at sea especially in high-density traffic. This study proposes a fuzzy rule-based model to create an asymmetrical polygonal ship domain for both restricted waters and open waters. The model takes into consideration various navigational factors which are determined as a result of expert interviews. A C# application based on fuzzy inference system (FIS) with Mamdani model has been implemented to create the size and shape of the domain. Finally, a few experimental tests and comparative implementations with other ship domains have been conducted to demonstrate the performance of the proposed system. The proposed ship domain will undoubtedly contribute to the ship traffic engineering and is considerably utilized in collision risk assessment and traffic design.