To address the dual demands of ship green transformation and maneuverability improvement, a novel electromagnetic end-plate collaborative spoiled rudder (EEPCSR) is proposed, and a comprehensive analysis of its hydrodynamic performance is conducted. Using the detached eddy simulation (DES) method, the hydrodynamic numerical simulations under open-water are carried out for the conventional rudder, the end-plate rudder, the collaborative spoiled rudder (CSR), and the EEPCSR. The optimal grid generation strategy is determined through grid convergence analysis, and the reliability of the method is verified by combining with model test results. The results show that the end plate can effectively suppress the rudder tip flow separation, while the spoiler significantly enhances the rudder’s lift; their synergistic effect achieves both enhanced rudder effectiveness and efficiency compensation. By adjusting the rudder angle and spoiler open angle, the efficiency of the EEPCSR is maximally improved by 31.2% under the constant lift condition compared with the conventional rudder. This study will provide reference and theoretical support for the engineering design and application of new-type energy-saving rudder devices.