Abstract: With the widespread promotion of green shipping concepts and increasingly stringent international carbon emission regulations, wind-assisted ship propulsion (WASP) has reemerged as a research focus in the shipping industry as an effective means of reducing energy consumption and emissions. This paper focuses on Flettner rotors and rigid sails, aiming to systematically evaluate their application potential and engineering feasibility in modern vessels, thereby providing theoretical and practical support for transitioning this technology from conceptual validation to large-scale engineering application. The study addresses key issues such as wind capture mechanisms, thrust conversion efficiency, ship-sail coupling dynamics, and deployment conditions on actual vessels. By employing a combined approach of numerical simulations, wind tunnel testing, and field trials on operational ships, it comprehensively analyzes the aerodynamic performance and energy-saving benefits of both types of sails under various sea conditions, heading angles, and hull configurations. Results indicate that both Flettner rotors and rigid sails exhibit high aerodynamic efficiency and can significantly reduce main engine power output and carbon emissions under specific operational profiles; however, their performance is considerably influenced by environmental and operational parameters, demonstrating distinct operational limits. In conclusion, while both technologies are currently in a transitional phase toward engineering application, future efforts should prioritize improving system reliability, promoting multidisciplinary design optimization, and accumulating long-term operational data to ultimately facilitate their scaled adoption in the global shipping system.