Motion induced operability loss in fishing vessels: Preliminary results

Fishing vessels operate under dynamic conditions that directly affect crew welfare and operational capability. Yet existing onboard welfare indices are not specifically designed for small and medium-sized fishing vessels. This study presents a preliminary assessment of vessel motions and their impact on operability using onboard measurements from two representative Catalan trawlers. Vessel dynamics were characterized using an inertial measurement unit (IMU). Steady-navigation segments were identified and analysed using three established indices: the Motion Sickness Incidence (MSI), ISO 2631 vertical acceleration thresholds, and the Motion Induced Interruption Index (MII). Results indicate that, under the analysed conditions, vertical accelerations and the associated MSI do not appear to be suitable indicators for assessing operability in fishing vessels. In contrast, lateral accelerations (MII) show a clearer relationship with task interruptions and crew stability, particularly during low-speed trawling operations, suggesting a greater relevance for describing onboard operability. Nevertheless, these findings should be regarded as preliminary, and further research is required to refine the analysis and to develop operability indices specifically adapted to the operational characteristics of fishing vessels and real working conditions at sea.