U.S. Customs and Border Protection approves floating turbine installation plans

4C Offshore | Tom Russell
By: 26/08/2021 CBP
The U.S. Customs and Border Protection (CBP) has issued a ruling regarding the installation of the New England Aqua Ventus floating offshore wind demonstration project and its compliance with the Jones Act and coastwise Towing Statute.

The 11 MW Aqua Ventus project is being jointly developed by Diamond Offshore Wind Development, RWE Renewables, and the University of Maine. It includes the installation of an offshore wind turbine on a semi-submersible floating concrete foundations in territorial waters off the coast of Monhegan Island, Maine. The foundation called the VolturnUS, was designed by the Advanced Structures and Composites Center at the University of Maine. The turbine is held in position in the ocean by three marine mooring lines securely anchored to the seabed, and connected by subsea cable to the Maine power grid by subsea cable.

The CBP ruling concerns whether the use of non-coastwise-qualified barges to assemble the hull of a floating wind turbine unit to be affixed in U.S. territorial waters violates the Jones Act, or the coastwise Towing Statute. The Jones Act specifically prohibits the coastwise transportation of “merchandise” between coastwise points by non-coastwise qualified vessels.

The project developers offered two options for the construction and installation of the foundation's concrete hull. One includes the construction of the entire hull at Mack Point in Searsport, Maine. Option Two concerns the construction of segments of the hull at Searsport or Brewer, Maine, which will be transported to Eastport, Maine for final assembly and launching.

In Option One, the hull will be fabricated on three to four barges lashed together at Mack Point in Searsport, Maine. Once the hull is completed, one or more of the barges will be used to tow the hull to a designated “oil transfer area” within Maine state waters. Two alternative were proposed as part of this option.


The first would see the use of one or more fabrication barges which would be non-coastwise. When the foundation is complete, it will be transferred from the fabrication barges to a coastwise-qualified launching barge. A coastwise-qualified tug will then tow the launch barge to the oil transfer area where the launch barge will be anchored. The launch barge will then submerge so that the concrete hull can be floated and towed by a coastwise-qualified tug to Sears Island, Maine, where the foundation will be ballasted down onto the seabed for assembly and installation of the turbine.


The alternative would see the use of coastwise-qualified barges for the fabrication of the foundation. When complete the coastwise-qualified barge will tow the fabrication barges to the oil transfer area where they will be moored next to a non-coastwise-qualified launching barge. The foundation will be transferred to the launching barge using a skid system. Following the transfer, the non-coastwise-qualified launch barge will submerge so that the foundation can be floated. It will then be towed by a coastwise-qualified tug to Sears Island, Maine, where it will be ballasted down onto the seabed for turbine assembly.


For Option Two, the developers proposed the foundation to be fabricated in segments in the upland areas at either Mack Point or Brewer, Maine. In either location, after construction, the hull segments will be laded onto a coastwise-qualified barge or barges. Coastwise-qualified tugs will then tow the barges to Eastport, Maine. In Eastport, three non-coastwise-qualified submersible barges will be lashed together and moored to the Estes Head Pier to form a construction platform. The foundation segments will be transferred from the transport barges to the lashed barges for assembly. During the assembly phase, the lashed barges may need to be moved off the pier so that other ships can temporarily access the pier. Such a movement will be accomplished by a coastwise-qualified tug or tugs.


Once the hull is complete, the lashed barges will submerge at the Estes Head Pier and the founsation will be floated off the barges. Once again, the concrete hull will then be towed by a coastwise-qualified tug to Sears Island, Maine, where the hull will be ballasted down onto the seabed for turbine installation. Following this, the completed wind turbine unit will be towed by a coastwise-qualified tug to a location near Monhegan Island, Maine for anchorage and operation.

The CBP has ruled that the proposed transportation in Options One and Two do not constitute a violation of the Jones Act, because the non-coastwise-qualified barges will not be involved in the transportation of merchandise between coastwise points. In addition, the above scenarios do not violate the Towing Statute, 46 U.S.C. § 55111, because all towing will be conducted by coastwise-qualified tugs.


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