Most fishing vessels are less than 100 m in length (LBP), which is not mandatory for the IMO standards for ship maneuverability. Therefore, research on estimating the maneuverability of fishing vessel hull shapes are somewhat lacking compared to that of merchant ship hull shapes, and at the design stage, the numerical simulation method developed for merchant ships are applied without modification to estimate the maneuverability. Since this can cause estimation errors, the authors have derived a modified empirical formula that can improve the accuracy of estimating the maneuverability of fishing vessels in a previous study. In this study, using the modified empirical formula, the IMO maneuverability evaluation items, the turning motion test and Z-test simulations were performed on the fisheries training vessel BAEK-KYUNG and compared with the sea trial test result to verify the validity of the modified empirical formula. In conclusion, the modified empirical formula was able to estimate quantitatively and qualitatively similar to the result of the sea trial test. Such a study on estimating the maneuverability of fishing vessels will be a good indicator for fishing vessel operators and will help them analyze marine accidents.

This study is intended to provide navigator with specific information necessary to assist in the avoidance of collision and in operation of ships to evaluate the maneuverability of research vessel Jera. Authors carried out full-scale sea trials for turning test, zig-zag test, and spiral test at actual sea-going condition, which were performed on starboard and port sides with 10-20 rudder angle at service speed of 10 knots. The turning circle was much different at both of the turning of port and starboard which was longer at the starboard than at the port. In the zig-zag test results, the port and starboard was 10˚ the first and second overshoot angles were 6.0˚ , 5.8˚ and 6.3˚ , 7.1˚ respectively and the first overshoot angles were 16.4˚ , 17.6˚ when using 20˚ . Her maneuverability index T and K can be easily determined by using an analogue computer with the data obtained from the zig-zag tests where K is a constant representing the turning ability and T is a constant representing her quick response. In the zig-zag tests under 10˚ or 20˚ at rudder angle, the value K is 0.149. 0.123 sec- and T is 11.853 and 6.193 sec and angular velocity is 0.937˚ /sec and 1.636˚ /sec. In the spiral test, the loop width was unstable at +0.51˚ and -1.19˚ around the midship of rudder, but the tangent line at 0˚ was close to vertical. From the sea trial results, we found that she did comply with the present criterion in the standards of maneuverability of IMO.