Assessing Motion Induced Loss of Operability on Small and Medium-Sized Fishing Vessels Through Motion Measurements

Resumen

Vessel motions directly affect the crew’s ability to perform onboard tasks, influencing both operational efficiency and safety. This study investigates motion induced operability loss in real fishing conditions using onboard measurements collected from a commercial coastal trawler operating in the NW Mediterranean Sea. A dataset of 19 fishing trips was acquired using a low-cost inertial measurement unit (IMU) and Global Navigation Satellite System (GNSS) receiver installed in the wheelhouse, enabling the continuous recording of vessel accelerations and trajectory during normal fishing operations. The analysis focuses on two established motion-related indices: the Nordforsk standard, based on root mean square (RMS) vertical accelerations, and the Motion Induced Interruption (MII) index, based on horizontal accelerations and task interruption probability. Results show a strong dependence of vessel accelerations on local wave conditions and operational regime. Lower vessel speeds are systematically associated with higher motion levels and increased exceedance of operability thresholds. Overall, the study demonstrates the applicability of existing indices to real operational data, while highlighting the need to adapt operability metrics to the specific conditions of small-scale fishing vessels.