Nylon Ropes for Mooring of Floating Offshore Wind Turbines: The NYMOOR Project

Abstract Effective mooring of floating offshore wind turbines (FOWTs) is challenging, and conventional mooring designs often require line components with quite large diameters. This is mainly a consequence of large mean environmental loads from wind, namely the wind thrust force, combined with a relatively stiff mooring system. Nylon ropes have the potential to reduce stresses in mooring lines due to their flexible and elastic behaviour. However, there is very little experience with use of nylon for permanent mooring of floating structures. Of particular concern is the long-term endurance and behaviour of nylon ropes in the ocean environment. Furthermore, new material models are required to simulate mechanical properties of nylon ropes, and design analysis tools must be further developed to accommodate these new models. The paper starts by presenting state-of-the-art in the topic of nylon ropes with focus on mooring applications. It reviews and documents advantages of nylon ropes in mooring of FOWTs with results from two case studies, and identifies knowledge gaps. Then it describes the NYMOOR research project, which addresses some of the knowledge and technological gaps. We start with the project objectives. The assumed hypotheses are formulated based on the best knowledge in the topic. Then the project methodology and the research activities are described in detail.