The authors regret an omission in the Acknowledgments and would like to revise it as follows: Project funded under the National Recovery and Resilience Plan (NRRP), Italy, Mission 4 Component 2 Investment 1.3 - Call for tender No. 1561 of 11.10.2022 of Ministero dell’ Universitá e della Ricerca (MUR); funded by the European Union – NextGenerationEU Award Number: Project code PE0000021, Concession Decree No. 1561 of 11.10.2022 adopted by Ministero dell'Universitá e della Ricerca (MUR), Italy, CUP, Italy E13C22001890001, Project title “ Network 4 Energy Sustainable Transition – NEST”. The authors would like to apologise for any inconvenience caused.

In the offshore wind energy field, reducing energy costs involves optimizing and analyzing each system component. A key component influenced by the installation site is the mooring system, which can be designed using various concepts. This study focuses on examining a taut-leg mooring system and its impact on the overall system behavior. Due to a lack of experimental data on taut-leg mooring systems for Floating Offshore Wind Turbines (FOWTs) in the existing literature, our work aims to provide the scientific community with an extensive experimental dataset to validate various numerical models and support the design process of a taut-leg mooring system for a selected installation site. The full-scale mooring system was designed, scaled down, and evaluated through experiments at a 1:96 scale using a mooring configuration realized with springs. Springs offer a constant axial stiffness, reflecting the ideal structural behavior. Our paper highlights significant observations for this configuration, even under off-design conditions with modified pre-tension levels. Regular and irregular waves were tested to establish a baseline hydrodynamic response, assess the wind turbine's impact on the floater, and evaluate operating conditions. An environmental contour (EC) was defined to analyze the system's behavior in ultimate and accidental limit states. System identification (ID) waves streamlined the characterization process by reducing the number of required waves. Additionally, free decay tests were performed to assess the system's dynamic characteristics at resonance. The analysis of experimental data reveals that pre-tension variations minimally influence the dynamics of the floating structure. Results showed that the tested mooring system exhibits stability during power production and withstands ultimate and accidental limit states.

Numerical modeling of the floating offshore wind turbine (FOWT) dynamics plays a critical role at the design stage of a floating wind project. Still, there exist challenges for verification of efficient engineering models against experimental results. Recently, an experimental campaign was carried out for a 1:96 downscaled model of the OC4-DeepCWind semi-submersible platform with mooring lines made of fiber ropes and chains. Leveraging the results of this campaign, this paper focuses on the development and calibration of a numerical model for the semi-submersible platform with a focus on the dynamic responses under bichromatic waves. In the numerical model, the hydrodynamic loads are modeled based on the potential flow theory with Morison drag. The lumped mass method is applied to model the mooring system. Both free decay tests and bichromatic wave conditions are considered in the model calibration process, and key uncertain parameters (e.g., mooring line length) that affect the response have been identified and discussed. Using the proposed calibration procedure, we establish a reasonably good numerical model for prediction of the platform motion and mooring dynamics. The low-frequency responses of the platform under bichromatic waves are well-captured. These outcomes contribute to the development of efficient numerical FOWT models under experimental uncertainty.