Context-Aware Maritime Navigation Efficiency Assessment: A Data-Fusion Framework with Metocean and Encounter-Based Validation

Maritime navigation efficiency is commonly assessed using isolated indicators such as route deviation, speed variation, fuel-related metrics, or traffic density, which do not fully reflect the operational context of a voyage. This study proposes a context-aware framework for assessing maritime navigation efficiency using GPS–AIS data fusion, planned-route geofencing, metocean integration, and AIS-based encounter validation. The methodology introduces the Navigation Efficiency Resilience Index (NERI), which combines target achievement, response cost, and disturbance intensity into a bounded and interpretable time-resolved indicator. The framework was demonstrated using a Singapore–Montevideo container ship voyage with GPS data sampled at 30 s, AIS traffic information, corridor-specific cross-track limits, and collocated metocean variables. The voyage-level mean NERI was 0.679, while the 10th percentile was 0.519, indicating that short-term low-efficiency episodes were concentrated mainly in constrained waters, approach areas, and metocean-intensive transition zones. Open-sea legs achieved higher mean NERI values, with 0.704 in the Indian Ocean and 0.736 in the South Atlantic, whereas lower values were obtained in the Malacca–Singapore TSS and Montevideo approach legs. GPS-based trajectory assessment provided more stable own-ship motion indicators than AIS-based assessment, whereas AIS remained essential for traffic-density estimation and CPA/TCPA conflict-window validation. Encounter-based validation showed that the full NERI formulation outperformed single-dimensional baseline indicators, achieving an AUROC of 0.83 and an AUPRC of 0.41 for conflict-window classification. The proposed framework provides a reproducible analytical layer for voyage monitoring, post-voyage diagnostics, and intelligent maritime decision-support systems.