Should Cape Wind become a reality, European installation vessels specializing in wind spar construction would be contracted through a US construction company to install the pods, jackets, turbines and blades. There are no US flag elevating wind farm ships nor is there a US corporation which would modify or really build a spec vessel for a single program, and thus an easy route around the Jones Act. There's quite a few out there. It doesn't take long to install the base, tower and generator system. Plus, the Dutch and Germans have installed hundreds already, they have the experience to sell the program safely to whichever state and federal agency needs to be sold. Lift boats and converted jackups aren't in the mix.
A US cable installation contact (union) has been tentatively contracted a few years ago to provide the subsea tie ends, cable runs, and shore landings.
They plan/ned to build and use two small crew boats, designed for wind farm use, to transport the maintenance crews as needed.
They have agreements in place for the local unions (Ma) for their personnel be engaged through the construction process and to provide maintenance crews (small numbers).
The work is virtually all closed shop. MA is politically union based. And Cape Wind has pursued politics as best as they could to keep their program alive. And politics in Ma is by appealing to the union.
Even before the fall of oil prices, Cape Wind was not doing well. With gas becoming cheap and available enabling power generation to auger future costs, gas generation is less expensive, with far less permitting than wind power, and too, as others have mentioned, without state and federal subsidies, wind is about as expensive as electricity can get. And lastly, orginally the principals (utility companies down south) behind CW were into the wind program to enable them to get enviro credits to build fossil plants in the southern Midwest. . Might happen, but doesn't look good with gas getting cheaper and more available by the day. And for all the stories told, aside from construction which would take not take as long as promoted, there won't be much followup...just like oil...once oil is running the pipeline no one remembers the process for getting the oil to flow to the pipe. A small maintenance crew. As one suggested, they might contract a few boats to help with logistics, but would imagine they'd be placating the local unions as much as possible as use as much local support before looking elsewhere.
In all, its not a likely event to happen at all, off Nantucket or anywhere else on the US shelf, unless its federally mandated....