The offshore infrastructure required for mooring a Pelamis WEC consists of a primary and secondary mooring system, machine rapid installation and removal systems, electrical export and communication systems and associated navigational aids and markers. This document gives an overview into the design of these components and systems, including the basis of design and methodologies used, along with specifications for the major components and, where appropriate, the rationale behind certain operational and design decisions as taken by PWP throughout the development of the mooring spread.
A vital consideration for any WEC during the early stages of design is the operations and maintenance strategy and methods for installation and removal of both the WEC itself and the moorings spread. In order to create an economically viable offering as a whole, developers must consider these aspects early in the design and optimisation process. PWP developed a number of innovative systems to enable offshore operations to be conducted with smaller vessels. Moving away from the anchor handling vessels originally used was a step change for PWP and a key learning point in the mooring development process.
PWP found third party verification to be a very valuable process once mooring design had been completed. It provides independent confirmation that the design in in accordance with good industry practice and employs a risk based approach based on Failure Mode and Effect Analysis (FMEA).