This is the author accepted manuscript. The final version is available from EWTEC via the link in this record.Device reliability is often considered essential to the performance of a wave energy converter. Developers may undertake a Failure Mode and Effects Analysis (FMEA) as a design process to evaluate the high priority failure modes of a prototype to approximate device reliability. However, failures identified by this process are typically predicted, and often lack validation from actual marine operations history. In view of this, an FMEA undertaken for the Albatern Squid 6 Series Wave Energy Converter (WEC) has been validated using historical failure rate and marine operations data. Results indicate that a high volume of major structural and hydraulic failures occurred in the initial stages of deployment, whilst minor electrical and instrumentation failures occurred towards the latter. A notable observation is that human driven failures constituted a much larger portion of failure occurrences than the FMEA predicted. As a general observation, the retrospective analysis of failure rate requires consistent data recording procedures, especially given the introduction of new innovations, which may cause a resurgence of early-stage faults. Lessons learned in the operation of a redundant, modular and accessible array are discussed in the view of designing devices that are not immune, but resilient to failure.The author gratefully acknowledges the support of the ETI and RCUK Energy Programme funding for IDCORE (EP/J500847/1), and the support of Wave Energy Scotland during the installation and commissioning of the Mingary Bay wave array
