Operability and stability assessment of Japanese and Vietnamese purse seiners under the combined action of fishing gear and waves

In this study, the stability and operability of Japanese and Vietnamese purse seiners are analyzed. Three purse seiners (135GT, 199GT, and VNM) were tested through a series of experiments involving transient waves to determine their transfer functions and capsize experiments in irregular waves with fishing gear load. A stability limiting boundary was developed to assess the risk of capsizing based on operability calculations and determine the maximum significant wave height at which the vessel can safely operate. The stability limiting boundary take into account the effect of fishing gear load and back rowing forces, as well as the direction of the wave. This stability limiting boundary can be used by fishermen to predict the wave conditions under which their vessels can operate safely. The relationship between the operability limiting boundary and the stability limiting boundary is presented. The study also compares the risk of capsizing in traditional and Japanese-style fishing methods. Results show that 135GT is less stable compared to the other two ships, while the Vietnamese purse seiner VNM has good stability but poor operability, even in average weather conditions.