The installation of the present wind farms Hywind Scotland and Hywind Tampen are both carried out by towing the fully assembled wind turbine from the assembly site in the Norwegian fjords to the final offshore site. In the present study an alternative installation method is proposed where the fully assembled tower is transported to the site on the installation vessel and mounted onto the preinstalled floating substructure (a spar buoy). The paper presents a brief outline of the design process for the proposed concept and gives an overview of the work done to evaluate variations of the installation vessel and the proposed lifting mechanism. The paper is a summary of the results obtained by a project team in SFI MOVE addressing marine operations related to installation of floating offshore wind turbines.