Enhancing passage planning with fuzzy logic for sea navigation: A hybrid approach to cross track limit determination

Safe navigation in passage planning depends on multiple factors, including ship maneuverability, size, speed, traffic conditions, and Cross Track Limit (XTL). Traditionally, XTL settings are based on company policies, navigator experience, and subjective risk perception, which often leads to inconsistencies. To address this issue, this study introduces a structured decision-support framework that integrates the Fuzzy Extended Analytic Hierarchy Process (FE-AHP) with a Mamdani-type Fuzzy Inference System (FIS). FE-AHP was applied to systematically identify and rank factors affecting XTL, while the FIS generated context-sensitive recommendations. The analysis differentiates between open seas and confined waters. In open seas, static ship-related factors such as maneuverability (MOS), length (LOS), and width (WOS) dominate, whereas in confined waters, dynamic and environmental variables, including draft (DOS) and the Category Zone of Confidence (CATZOC), play a more decisive role. Numerical experiments demonstrated practical applicability. In open seas, XTL values ranged from 1.46 Nm in unfavorable conditions to 4.54 Nm under optimal ones, depending on ship features, navigator experience, and traffic risk. In confined waters, values were narrower, between 0.12 Nm (high draft, low CATZOC, inexperienced navigator) and 0.85 Nm in favorable settings. These results highlight that while open seas allow wider maneuvering margins, confined waters critically constrain navigation due to environmental and operational factors. By combining expert knowledge with quantitative modeling, the FE-AHP + FIS framework reduces reliance on subjective judgment and improves consistency in XTL determination. This structured approach supports more informed, data-driven passage planning and contributes to safer, more efficient maritime navigation.