I wonder if they could use an underwater wing design, similar to this (https://www.youtube.com/watch?v=u5SHn0SdXjw https://www.youtube.com/watch?v=u5SHn0SdXjw).

I wonder if they could use an underwater wing design, similar to this (https://www.youtube.com/watch?v=u5SHn0SdXjw https://www.youtube.com/watch?v=u5SHn0SdXjw). You keep swapping the angle of the wing so it's always pushing forward whether the vessel is moving up or down, but it would be powered by the waves moving the ship. It might be possible to get a slow base load speed for 'free' with a large enough wings