Intermediate-scale sea testing of the Hexafloat floating offshore wind turbine: Initial investigation at MaRELab

Floating offshore wind turbines (FOWTs) are increasingly vital for harnessing wind energy in deep waters, such as the Mediterranean Sea, where complex environmental conditions limit fixed foundations. This study presents an intermediate-scale (1:7) experimental investigation of the Hexafloat TM floating wind turbine platform at the MaRELab facility, focusing on hydrodynamic responses under wave excitation without aerodynamic loading. Here we conducted extensive offshore testing, analyzing time-domain trends, spectral characteristics, and response amplitude operators (RAOs) for platform motions and mooring loads. Results reveal a near-linear increase in platform motions and a quadratic rise in mooring tensions with wave height, with spectral peaks aligning with expected frequencies and RAOs confirming stable dynamic behavior. These findings validate the platform’s design and experimental approach, demonstrating the Hexafloat TM concept’s suitability for deployment in challenging offshore environments and providing a robust dataset for numerical model validation and future development.