Abstract: The complex vortex structures induced by a submarine sail have adverse effects on its own drag. To address this issue, at a high Reynolds number of Re=1.1×10⁶, this study adopts the improved delayed detached eddy simulation (IDDES) method to systematically evaluate the energy-saving and drag-reduction effects of blowing/suction control. The control is applied individually at the fixed end or the free end of the sail, and also in multi-position combinations. The flow physics and control mechanisms are revealed based on changes in surface pressure and flow structures. The results show that, under individual control conditions, free-end suction (S1 suction) actively removes near-wall fluid. It accelerates the flow around the slit and forms a local negative pressure. A drag-reduction rate of 5.8% is achieved, but the net energy saving is −54.8%. Fixed-end suction (S2 suction) mainly weakens the local recirculation. It achieves a drag-reduction rate of 2.0%, and the net energy saving is −59.2%. In contrast, fixed-end blowing (S2 blowing) and free-end blowing (S1 blowing) induce local low pressure through high-speed jets. Their drag-reduction rates reach 24.7% and 34.8%, respectively. Their corresponding net energy savings are −13.8% and 1.3%, respectively. Among them, S1 blowing can effectively reduce the streamwise vorticity intensity of the free-end tip vortex, while S2 blowing reduces the intensity of the base vortex. The S1 blowing case simultaneously obtains a relatively high drag-reduction rate and a positive net energy-saving benefit. It exhibits the best overall energy efficiency. With the further adoption of combined control of synchronous S1 and S2 blowing, the drag-reduction rate increases to 55.1%. The pressure drag is reduced by 66.62%. At the same time, both the pressure coefficient and the friction coefficient on the free-end surface decrease. The streamwise circulation of the tip vortex decays more rapidly. The overall vorticity in the wake region is further weakened. However, because the combined control requires additional blowing energy, its net energy-saving rate is −11.9%. Individual S1 blowing is more suitable for operating conditions that balance drag reduction and energy utilization efficiency. Combined blowing control obtains the maximum drag-reduction effect at the cost of a certain overall energy efficiency. It is more suitable for operating conditions with a higher demand for drag reduction.