[dzhiurgis]

I think such rotating sails could be almost called 'solid state' - basically zero hassle compared to a traditional canvas where there is always person on lookout, trim before wind picked up, make sure rigging is maintained, etc. That said these probably produce way less power.

[jhayward]

Rotating sails and wind turbines have historically been extremely high maintenance due to the forces the long moment arm puts on the rotational coupling at the base.