<p>This study aims to enhance the maneuvering advantages of the waterjet unit through parametric design, performance evaluation, and optimization of the one-piece waterjet propulsion steering and reversing gear (SRG). The SRG’s performance evaluation stems mainly from the effect of the free surface, the varying sailing speeds of the ship, and its performance while functioning at the stern of the waterjet-propelled vessel. Parameters such as the length, width, and height of the steering gear, as well as the inclination, width, and curvature of the reversing gear, significantly influence the SRG. Although the free surface has a great impact on the force of the SRG, its performance trend remains unaffected. When the SRG operates at the stern of the ship, the optimized scheme’s lateral force improves by an average of 8.08% for sailing with a rudder angle condition and an average of 45.69% for reversing sailing with a rudder angle condition. The longitudinal force of the optimized scheme improves by more than 23% when sailing without a rudder angle condition and by an average of 31.75% when sailing with a reversed rudder angle condition. Additionally, the speed of the rotor has a minimal effect on the lateral force and a significant effect on the longitudinal force.</p>