Objective Assessment of Maritime VHF Communication Competence Using a Real-Time Simulation Framework

VHF radiotelephony remains a fundamental component of maritime safety and is mandated by the STCW Convention as an essential operational competency for seaferer. However, existing studies largely focus on basic button-level interaction and rarely incorporate real-time voice transmission, multi-user communication, or standardized performance assessment. This study introduces a simulation system for the Sailor SP3520 portable VHF radio developed in Unity, integrating real-time voice exchange through the UDP protocol combined with Photon Voice. The framework accurately reproduces half-duplex behaviour, communication latency, channel switching, scanning modes, power settings, and Push-to-Talk operations, while supporting STCW/SMCP-based training scenarios. A multi-dimensional competency assessment rubric was designed to evaluate learner performance in technical operation, phraseology, situational awareness, and radio discipline. A pilot study involving second- and third-year students demonstrates clear cohort-based performance differentiation, consistent error reduction patterns, and procedural compliance trends aligned with training progression. The core contribution is a multi-dimensional performance assessment framework that combines system-logged interaction data with a structured rubric to quantify technical accuracy, channel selection errors, Push-to-Talk misuse, and teamwork-related radio discipline. The findings confirm the potential of Unity-based VHF simulation as a reliable tool for STCW-compliant training and highlight its applicability for multi-user and remote learning environments in the digital transformation of maritime education.