Scaled mooring design for hydrodynamic testing of floating wind platforms: Introduction of the Spring Selection Tool

Abstract

As the floating offshore wind (FOW) industry approaches commercialisation, the need for representative hydrodynamic tank testing becomes vital to support technological development and provide confidence prior to field deployment. The representation of turbines, blades and floaters in scaled tank tests has been widely studied. However, accurately representing scaled mooring systems in the tank remains challenging due to limitations imposed by the facility dimensions and project time constraints. This paper addresses these challenges firstly by investigating the relationships between full-scale FOW mooring system design parameters and their scaled counterparts. Furthermore, a novel spring selection tool (SST) was introduced to streamline the design of scaled mooring lines in model tests. A case study of the 1:50 scale mooring design for hydrodynamic tank testing of the Trivane 15 MW FOW platform demonstrated how to prioritise and compromise certain mooring parameters for tank testing, and showcased the SST’s flexibility and efficiency. Initial results from this case study indicated that the tank mooring accurately replicated first-order platform motions when compared to OrcaFlex numerical model predictions. Additionally, this case study highlighted the importance of incorporating both the elastic and geometric stiffness components in the tank design of a semi-taut mooring. The outcomes of this work aim to improve the robustness of tank mooring design and set-up, contributing to more accurate and reliable hydrodynamic testing of FOW platforms.