A US mariners' association signalled it could compromise on measures under consideration in Congress by exempting turbine installation vessels (WTIVs) from requiring 100% American or same-flag crews – but experts warned that would still leave the nation's offshore wind industry badly hampered.

The crewing measure was added as an amendment to a routine Coast Guard authorisation bill last March and would require all vessels operating on the outer continental shelf (OCS) to be fully staffed by either American citizens or authorised aliens, or those from the same country as the vessel’s registration.