An analysis of floating wind turbine towing operations using OpenFAST

Abstract The floating wind industry is slowly entering the commercialisation phase and array-scale floating wind farms are imminent. Irrespective of the type of floater used, towing operations represent a crucial marine activity required during installation, major repairs and decommissioning phases. Numerical analysis of towing operations is vital for predicting hydrodynamic motions and towing loads, enabling the identification of metocean limits crucial for achieving optimised safe and efficient execution. This paper presents a unique approach to utilise OpenFAST for the examination of towing operations. Compared to other numerical analysis tools available in the market, OpenFAST stands out as a free, open-source tool specifically designed for wind turbine analysis. The study introduces and evaluates an analytical method using OpenFAST, demonstrating its efficacy in modelling towing dynamics, predicting forces and assessing motion responses of a semi-submersible floating wind turbine in varying wave conditions. The numerical simulations are compared against the results from an experimental campaign. The capability of the method in simulating towing dynamics and the prediction of motion responses are discussed.