Twenty years ago, it was felt that a scheme most suitable to attain an acceptable, favorable benefit to cost ratio (“rentability”) would be one in which rotors would be anchored, but suspended in mid-water—precisely to avoid wave influence—and let drive hydraulic pumps, while conversion to electricity would occur at a central facility servicing several rotors; if these were spaced over some distance, the dephasing due to tide variation would be compensated in partim. More turbines could be inserted in the system, an idea based on the belief that cost would be rather low.
Fifteen years ago, it was suggested to anchor in a line a series of floating turbine and generator units along the flow of the tidal current. A Savonius-type rotor might fulfill the role, however, due to the large size needed, a string of units would have to be stretched over at least half a kilometer; if the rotors drove, instead, hydraulic pumps a hydraulic motor could combine each rotor’s output, but then we would be back at the 1980s proposal. Finally, as an alternate turbine-generator, a horizontal-axis free-stream machine could be used, though with a nine-meter diameter required.
Musgrove has felt that the most straightforward tapping scheme would be an underwater equivalent of a windmill. So has Heronemus. Musgrove’s scheme used vertical rotors.