Hi Doug, yes: I just corrected.
Yes, this is well known, so the whole calculation takes into account of the lower efficiency of VAWT.
On the description there is air cushion between the reservoir of water under the blade and the water of the sea. But there is no detail about how air cushion would work. I agree that this point is questionable but it concerns only an use of the carousel as flywheel, not the carousel by itself. Moreover the generator is settled in the center: so as the angular speed is very low, big gear would be required.
The solidity could be about .1 or .2. If it is .2, the whole blades would cover one mile X 0.125 mile/5. So it is sure that for an equal power this VAWT carousel would use far more material than HAWT. But in the same time it would use far less land/sea area, and likely less anchors.
Below is how a blade could be:
https://www.oceanbirdwallenius.com/the-vessel/
