Somewhat like Kite Power Systems (KPS) but with ships with hydro generators instead? If you’re using hydro generators you don’t really need to travel upwind, just like with flygen where the tether length is mostly fixed? What would be the efficiency and expected power output of using hydro generators vs powering the drum on the buoy?
Another idea would be to use buoys instead of towers and maybe use ships, but then probably a problem is that the ships would want to always be downwind of the buoys. Maybe that’s solvable by connecting them in a lower radius loop and letting them go around the inside of the buoys for example, or not connecting them and doing something else and letting them go around the outside of the buoys. Or maybe have the buoys be submerged instead so the ships can go both inside and outside of them.
If the loop that went through the carriages were a rigid ring instead, or if the carriages were mounted on a rigid ring, it wouldn’t necessarily be, you could let the ring lift the carriages. The carriages now being connected to the towers with extending and retracting lines Battle Angel Alita:
If the loop is fully tensile you’d have to find a way so that the carriages stay in relatively the same position no matter if there is currently a kite train overhead or not.
You’d perhaps do something inspired by space nets. You’d still need the two inner loops as mounting points for the kite perch, but now between those and the outer loop that goes through the carriages you’d perhaps add (additional loops) with bridling between them so that the loop going through the carriages has more bridle lines going to it. The problem with that is that if the bridling doesn’t change in length it would be slack during rest, everything would droop and fall to the ground during rest when not supported by the kites, like a tent without its tent poles. You’d also have the extra drag from the extra (loops and) bridle lines.
Or maybe only the loops would be slack. The bridle lines and the kite tether would be suspended between the ground station and the loop going through the carriages. That would be a long span though. I don’t know what that would look like and if it would be better to have the loops or not.
In an offshore system you could move the central buoy away from the center of the circle. I an onshore system you could put the ground station on a circular/elliptical track, inside and concentric with the towers, the radius optimized for the desired elevation angle. You’d move the ground station based on the wind direction.