Operability analysis of traditional small fishing boats in Indonesia with different loading conditions

According to the Food and Agriculture Organization, fishing at sea is a risky activity with the highest mortality rate due to accidents. Many ship accidents are experienced by small ships, especially on boats with a length of smaller than 24 metres. With a large number of small fishing boats in Indonesia, the risk of potential ship accidents is high. Therefore, an operability analysis must be carried out for various loading conditions to address any safety issues due to severe vessel motion in advance. The operation of fishing vessels is different from that of merchant ships. The net cargo of merchant ships tends to remain unchanged during a voyage. By contrast, the net cargo of a fishing boat, which is fish caught, will change during its operation at sea. This change will also affect the ship’s seakeeping characteristics. This study aims to determine the effect of changes in load and their effect on a traditional fishing boat’s operability in Indonesia, taking into account the ship’s intact stability. In addition, this study also highlights the response of the ship roll motion to prevent stability failure. The stability curve is used to relate ship stability analysis to seakeeping analysis. Percentage operability and Operability Robustness Index are used to assess the root mean square (RMS) roll response and the ship's expected maximum roll motion. In this study, it is shown that the percentage operability of the fishing boat satisfying all pre-determined seakeeping criteria varies between 61% to 74%. Among all criteria, the limiting boundary for RMS roll motions and RMS pitch motion are relatively low, affecting the overall operability.