The safety and stability of mooring systems for floating offshore wind turbines (FOWTs) are crucial for efficient power generation under wave and combined wind-wave conditions. This study examines the hybrid mooring system integrating buoys and clump weights, which show potential in mitigating platform motion responses. An investigation of the effects of key parameters on the OC4-DeepCwind platform with buoy and clump weight is conducted using ANSYS-AQWA, focusing on a multi-segment hybrid mooring system with single buoy and single clump weight (MSM-BSW). A representative improved configuration under the North Sea wave condition, denoted as MSM-BSW-D, features a buoy radius of 3.5 m, a clump weight radius of 3.5 m, and a clump weight positioned 40 m from the platform. Based on minimal surge motion response variation, a new model featuring multi-segment mooring lines with multi-buoys and multi-clump weights (MSM-MMW) is proposed. The wave-frequency, low-frequency, and total responses of OC4 mooring system, MSM-BSW-D, and MSM-MMW under regular wave conditions are compared. The results show that, compared with the original OC4 mooring system, MSM-BSW-D and MSM-MMW reduce the average wave-frequency surge response by approximately 6% and 12%. While MSM-BSW-D reduces the average wave-frequency pitch and heave responses by approximately 79% and 56%. MSM-MMW also shows lower sensitivity to low-frequency wave loads. Under two wind-wave conditions, MSM-BSW-D and MSM-MMW reduce wave-frequency surge, pitch, and heave motions under the operating condition, while the latter has superior performance in parked condition. Further analyses of mooring-line tensions show that MSM-MMW suppresses surge and pitch fluctuations and reduces the maximum tensions in the primary loaded mooring lines under extreme conditions, although it redistributes higher mean loads to these lines. These findings indicate that optimizing buoy and clump-weight configurations can effectively improve the dynamic performance of FOWT mooring systems, and that the proposed MSM-MMW configuration shows greater potential for enhancing platform stability under extreme wind-wave conditions.
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