An Experimental Study on the Manoeuvrability of the KLNG2 with Different Speeds by Free Running Model Tests

This study evaluates the manoeuvring performance of the KRISO LNG carrier (KLNG2) using a 1/80 scale model in Free Running Model Tests (FRMT) at full-scale speeds of 5, 15, and 19.5 knots. The programme included 35° turning-circle and 10/10, 20/20 zigzag tests. Turning results showed that advance and tactical diameter remained stable and showed only minor variation with speed, remaining below the IMO limits used for reference comparison. In zigzag tests, overshoot angles generally increased with speed. Notably, overshoot angles in the 20/20 tests showed a trend similar to that of the 10/10 tests despite the difference in rudder angle. The speed-dependent variations were normalized by the corresponding IMO limits : the tactical diameter showed a minimal variation of 4.6% against the IMO limit, while the first overshoot angles in the 20/20 and 10/10 tests varied by 28.9% and 24.8%, respectively. The findings provide a reliable benchmark for large LNG carrier design and the validation of numerical simulations.