Turbine spacing unites offshore wind executives 

One nautical mile width called fishermen-friendly, a tanker, cargo ship go-around.

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This map shows how the corridors would be created for offshore wind farms.

Updated 11:30 am

Executives representing the offshore leaseholders off Martha’s Vineyard and Nantucket announced their joint support for a one-nautical-mile width between all their proposed wind turbines.

The executives also announced agreement on an east-west orientation of the wind turbine rows. Orsted North America president Thomas Brostrom, Equinor Wind US president Christer af Geijerstam, Eversource Energy-enterprise energy strategy executive vice president Leon Oliver, Mayflower Wind president John Hartnet, and Vineyard Wind CEO Lars Thaaning Pedersen signed a letter to the U.S. Coast Guard advocating for the one-nautical-mile spacing and east-west configuration. The letter was accompanied by a report executed by W.F. Baird & Associates Ltd. that concludes such distancing and orientation of turbines is advantageous. 

For Vineyard Wind, the width is a mile short of what it previously supported. As The Times reported in December 2018, Vineyard Wind was in support of two-mile transit corridors, while fishermen pushed for four-mile corridors. However, the executives contend in their letter that the widths are “responsive to fishermen’s requests.” Among other reasons, fishermen in Rhode Island and Massachusetts have pushed for wider navigation spaces between wind turbines for safety reasons, due to the length of mobile gear some fishing vessels trail. The executives state the width they propose addresses mobile gear concerns.

“Commercial fishermen working in the region have consistently advocated for turbines to be oriented in [east-west] rows, to accommodate longstanding practices designed to minimize conflict between fixed and mobile fishing gear,” the executives wrote. “Considerable written and oral public comments have urged adoption of 1 [nautical mile] spacing between turbines so as to better facilitate fishing operations among the turbines. Fishermen have also asked that turbine layouts be consistent across lease areas so as to avoid changing their operations as they pass from one lease area into the next. Members of the Rhode Island Fisheries Advisory Board, the Massachusetts Fisheries Working Group, fisheries groups that serve as representatives to the leaseholders, fishing fleet operators, and fish processing companies, as well as the National Marine Fisheries Service, have all expressed support for one or all of the following design elements: a uniform layout across the entire [Northeast wind energy area], [east-west] rows, and at least 1 [nautical mile] spacing being turbines. The 1×1 [nautical mile] turbine layout proposed here would provide each of these requested design elements, precisely as requested by the fishing industry.” 

The executives state their proposed layout of the combined lease area “creates 231 transit corridors, in four cardinal directions.” For vessels traveling north to south or south to north, east to west or west to east, the corridors remain at one nautical mile, the accompanying report indicates. For vessels traveling diagonally to those directions, the corridor widths shrink to 0.7 nautical miles. 

“Fishing vessels will be able to transit through the [wind energy area] … and also have the option to transit around the [wind energy area],” the report states. Using data from fishing boats tracked by their automatic identification systems (AIS), the report noted many fishing boats have preferred routes in or near the lease area. “A significant portion of the AIS fishing vessels are transiting to the west of the [wind energy area],” the report states, “and to the north or near the northern-eastern boundary of the [wind energy area]. Those fishing vessels that choose to transit around the [wind energy area] are expected to have no or small impacts, of 30 minutes at most, in transit times by avoiding the [wind energy area].”

For most tankers, cargo vessels, and cruise liners, the report expects they will avoid transit through the wind turbines: “Given the turbine layout assumed for this analysis, it is expected that vessels greater than 400 ft [length overall] or that exceed the air draft limits of the turbine blades will transit around the [wind energy area]. This would include many of cargo, tanker, and larger passenger vessels, but not fishing vessels (as all observed had a length of less than 400 feet).”

The report went on to recommend these bigger vessels steer clear of the lease area to hedge against hitting other vessels.

“Based on considerations of collision avoidance, it is recommended that vessels exceeding 400 feet should transit around the [wind energy area],” the report states. “Vessels of this size were observed to be tanker, cargo, passenger, or military vessels. Transiting around the [wind energy area] may also provide a suitable option for much of the existing fishing vessel traffic, since the majority of fishing vessel traffic skirts the northwest and northeast boundaries of the [wind energy area], and results in little (less than 30 minutes) or no increase in transit times for these vessels.”

The report concluded “designated transit corridors” don’t appear to be needed, as the proposal provides a multitude of navigable passages simply due to the unified spacing and configuration of the wind turbines.

“If the [U.S. Coast Guard] identifies the need to have designated transit corridors, then certain of the available corridors within the uniform turbine layout could be designated as one-way transit corridors,” the report states. “For example, in each direction, it would be possible to designate one-way transit corridors, with a potential separation corridor between opposite directions of transit.”

The report makes no mention of the potential for radar interference that the turbines might cause, either for vessels transiting or skirting the lease area. As The Times reported in August, wind turbines can have a deleterious effect on weather, aeronautical, and marine radar. 

In a statement to The Times, Meghan Lapp, fisheries liaison for Rhode Island’s Seafreeze Ltd. and a board member of the Responsible Offshore Development Alliance (RODA), found the executives’ announcement foreseeable, and as evidence they may not be taking fishing industry input to heart. 

“The announcement of standard turbine layouts does not come as a surprise; at multiple previous meetings, that was discussed as essentially an unofficial Coast Guard prerequisite regarding safety concerns for adjoining lease areas,” she wrote. “But what does come as a very unpleasant surprise is the developers’ assertion that the fishing industry now does not need transit lanes. These same developers were present at multiple state- and RODA-sponsored industry/developer transit lane workshops where it was very evident that the fishing industry needed and requested diagonal transit lanes through the areas, as well as minimum [four]-nautical-mile spacing for those transit lanes, which might need to be wider depending on the height and extent of radar interference from the turbines. For the developers to ignore all the input they received via those workshops and say, ‘We are being responsive to fishing industry needs,’ is extremely disingenuous.”

Updated to include comments from Meagan Lapp. —Ed.