I can't find the information to link to, but I think you guys are wrong about "nobody is grinding". I'm pretty sure there are 8 grinders on each boat and they are grinding constantly into a hydraulic accumulator (pressure vessel that builds up hydraulic pressure). And then everything above the waterline is actuated using hydraulic cylinders that use this pressure. Also I think the control systems are very limited - they can only be digital logic and every action has to be initiated by the crew. So adjusting the foils or the sails is controlled by people. The digital logic translates a single button press or lever adjustment into the appropriate hydraulic valves opening and closing.
Everything below the waterline (The foils and rudder) are actuated with battery power though