This paper describes the design and third-party assurance process of an innovative feeder concept of the Wind Turbine Installation Vessel (WTIV) with lifting module. An efficient wind turbine installation process is vital to the future rapid development of offshore wind farms in the US. The main challenges during the installation phase are related to the time and cost, physical boundaries in reaching the ports, and Jones Act requirements in the US. Therefore, industry is putting efforts into new installation concepts, such as feeder vessel-based methods. A novel feeder solution utilizes a non-Jones Act WTIV leveraged with existing cantilever and jacking technology from the oil and gas industry. The WTIV is outfitted with a removable L-shaped module, similar to a forklift concept, that can raise and secure a feeder barge above the waves. This provides a fixed installation platform and a static crane lift, enhancing safety and efficiency of the turbine installation process. The paper outlines efforts to design the barge lifting structure, WTIV / lifting module interface, and barge / lifting module interface. Impact on subsequent docking and lifting of the feeder vessel, and elevated operations with the feeder vessel, are explained. Engineering challenges encountered during the design process are discussed, and their implications on technical, operational, supply chain, and environmental, social and governance (ESG) benefits of the concept.

The feasibility of the present concept has been confirmed by an Approval in Principle (AiP) process undertaken between the designer, and the Classification Society and Marine Warranty Survey (MWS). Class review covered the WTIV design with load considerations from a novel barge lifting module. MWS review covered technical aspects for the transit and jacking of the WTIV, transport of the loaded barge to the offshore location, docking/undocking of the barge into the lifting module, lifting/elevating of the module and the following installation operations. Unique holistic AiP process considered both design, regulatory and operational aspects of the concept, which brings confidence to project stakeholders that all relevant risks have been identified and mitigated at the design stage.

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