Final decisions, which must be approved by the environment minister, are expected in early July.
Geotechnical, geophysical and meteocean studies revealed site conditions more complex than expected, Ailes Marines said. The use of jacket foundations, although technically feasible, would require a longer installation time, it added.
While it has not ruled out jackets, the consortium is also looking at gravity-based foundations. However, local fishermen are strongly opposed, arguing that they take up more space and are less environmentally friendly.
Changing to Areva's 8MW turbine may help as only 62 machines would be required and would be spaced further apart. In addition, electricity production would be higher for the same installed power, the consortium claims.
In a separate development, a demonstrator of Seatower's new "Cranefree" gravity-based foundation will be installed in early 2015 at the Fécamp site being developed by a consortium led by EDF Energies Nouvelles.
The hybrid concrete and steel structure can be towed by conventional tugs, thereby reducing construction costs and installation risks, Seatower said.
French construction giant Eiffage will manufacture the demonstrator at Le Havre while MT Højgaard will manage the installation process. The unit will be fitted with a Lidar to collect data for future optimisation of the technology.