If you are suspending a lot of heavy weights, you need something buoyant enough to hold them all up. An old supertanker would work fine. You make tunnels from

If you are suspending a lot of heavy weights, you need something buoyant enough to hold them all up. An old supertanker would work fine. You make tunnels from the bottom up to the reels, for the cables to run through. You would want to let it turn to face waves, but you need and electrical tie-in to shore, or anyway to the nearest wind farm to move power in and out. All the weights hanging deep under water keep it stable. Motor/generator and winch are maybe where the engine was.