Seawind also wants to do floating wind, also with two blades instead of three: Slow Chat III - #139 by Windy_Skies. They use a teetering hinge.
The history of Growian, another two-bladed downwind turbine: Slow Chat III - #138 by Windy_Skies.
And Nautica Windpower is linked on Floating wind turbine - Wikipedia, but I didn’t see recent activity.