The utilisation of synthetic mooring ropes for marine renewable energy (MRE) devices is a recent occurrence. Despite current use in the o shore industry, MRE mooring components are typically subjected to highly dynamic loads, necessitating the detailed characterisation of operational and long-term component performance for lifecycle analysis and operations management. To address the uncertainties associated with synthetic mooring components in this application, tension experiments have been conducted on nylon 6 parallel-stranded rope samples at IFREMER, France and the University of Exeter, UK under the consortium MERiFIC (Marine Energy in Far Peripheral and Island Communities). Measurements are reported from harmonic loading tests with di erent initial bedding-in levels used to investigate the in uence of load history on the immediate dynamic properties of the rope. Two irregular load regimes were also applied based on mooring tensions recorded by the South West Mooring Test Facility (SWMTF). Datasets are provided to facilitate the development of rope modelling tools. For the load regimes studied it was found that the operational performance of the rope is strongly in uenced by the instantaneous load-strain characteristic. This study provides unique insight into the sti ness and damping properties of synthetic rope in the context of loading regimes relevant to MRE devices.

In order to design marine renewable energy mooring systems which are both economical and durable it is necessary to establish the lifecycle performance of individual components. In parallel with numerical tool development, physical component testing utilising realistic load cases is pivotal in achieving a greater understanding of performance variations including the contribution of degradation mechanisms. Building upon previous experimental tests conducted by the authors, tension-tension tests were conducted on a sample used in rst part of the study and samples extracted from a mooring line which was deployed for 18 months with the South West Mooring Test Facility. In agreement with the rst part of the study it was found that sample axial stiness and damping are inuenced by load history and instantaneous strain. The increased compliance, lower load bearing capacity and reduced tension-tension fatigue performance of aged specimens are symptomatic of bre-on-bre abrasion damage sustained in service. Visual inspections of the rope and yarns including scanning electron microscope analysis of bres revealed that abrasion wear was accelerated by debris found within the rope structure, highlighting the importance of preventing particle ingress. Datasets are provided to facilitate the development of rope and mooring system simulation tools.

The reliability and integrity of components used in the marine offshore environment is paramount for the safety and viability of offshore installations. The engineering challenge is to design components that are robust enough to meet reliability targets whilst lean enough to minimise cost. This is particularly the case for offshore marine renewable installations which operate in the same, possibly harsher, environment as offshore oil and gas installations, and are subjected to highly cyclic and dynamic wave, wind and operational load conditions. The cost of electricity produced has to compete with other means of electricity generation and does thus not offer the same profit margins available as oil and gas commodities. As a result, components for marine renewable installations have to meet the target reliability, without the application of costly safety factors to account for load and environmental uncertainties. Industries with similar design tasks such as the aviation or automotive industry have successfully used a service simulation test approach to develop robust yet lean designs. This paper builds on an approach to establish and validate the reliability of floating renewable energy devices in which dedicated component testing using the purpose built Dynamic Marine Component test rig (DMaC) plays a pivotal role to assess, validate and predict the reliability of components in the marine environment. This paper presents a test rig for both static and fatigue tests of marine components such as mooring lines and mooring shackles under simulated or measured load conditions and provides two case studies from recently conducted mooring component tests. This includes an investigation into the load behaviour of synthetic mooring ropes and the ageing of mooring shackles.