With the growing global emphasis on environmental protection and sustainable development, the shipping industry is facing severe pressure to reduce emissions and save energy. As a clean and renewable energy source, wind energy demonstrates significant potential in the field of ship auxiliary propulsion. This paper takes the KVLCC2 ship as the research object and establishes a three-degree-of-freedom mathematical model for ship motion. The thrust and moment generated by a specific type of sail on the hull in a wind field are introduced as additional terms into the model, enabling the simulation of the sail-assisted ship's motion under wind conditions. Simulation studies on the turning and zigzag motions of the sail-assisted ship reveal that the sail has a significant impact on the ship's maneuverability. Under a wind speed of 8 m/s, the sail increases the ship's turning drift distance by 38.4 m (accounting for 12% of the ship's length) while also increasing the ship's speed during the turning process by 28.1%. In zigzag motion, the sail increases the ship's overshoot angle, particularly during upwind turns, where the second overshoot angle increases from 18.4° to 25.7°. Under beam wind conditions (±90°), the sail induces an asymmetric effect on the ship's steering. The auxiliary effect of the sail is more pronounced during downwind steering, whereas upwind steering requires an increase in the rudder angle for compensation.