A risk matrix based on the performance of ship manoeuvrability under wind force

Prediction of ship manoeuvrability behaviour under wind forces in different water depths is important from the marine safety perspective of surface ship operations. The hydrodynamic performance of ship maneuvering is altered, particularly when a ship maneuvers in coastal water and under the wind force that is blowing at different angles and speeds. In the present study, based on the MMG mathematical model, the 20/5 zigzag manoeuvre is investigated on the KVLCC2 tanker using an empirical modular model. The hydrodynamic and added mass derivatives are selected from existing literature, and the aerodynamic coefficient on the tanker is estimated using an empirical approach. Different operational scenarios are proposed for various wind angles, wind speeds, ship speeds, and depth-to-draft ratios (h/T) to determine the dangerous scenarios based on the trajectory and indices performance to be avoided. The results clarify that the rudder angle response, in terms of early or delayed action, is influenced ath/Tof 3, higher than ath/T= 1.2, especially when the ship speed reduces to 75% of its full speed. Moreover, a risk assessment matrix is developed based on ship manoeuvring performance in terms of rudder angle, heading angle, yaw rate, and drift angle. The findings reveal that ath/T= 3, the risk level significantly increased as soon as the ship speed reduced, and the manoeuvring capability ath/T= 3 is much lower thanh/T= 1.2, even at a wind speed of 5 m/s.