The shortlisted designs include a boat with suspension inspired by Paris to Dakar rally-winning cars, and a giant-keeled personnel transport vessel nicknamed the "Seahorse".
The companies involved are South Boats with Ad Hoc Marine, BMT Nigel Gee /Houlder, Nauti-Craft, ExtremeOcean Innovation, Umoe Mandal and Divex.
They are being developed under the Offshore Wind Accelerator (OWA) collaborative R&D programme, which aims to boost the economics of wind power in the harshest sea conditions by as much as £3bn ($4.8bn)