Really nice puzzles. I'm weirdly a huge fan of the ghost ship foreshadownig. It menacingly cruising in the backgrounfd until you actually meet it.
I also enjoyed the art-style and model design. But I think there should be more visual destinction between the ship types, because I often got confused which is which and just went off of how the canonball bounced around. I would do it this way: The medium ones are fine as they are. The big ships would be replaced by huge dark medieval cargo ships filled with crates and other wooden and stone stuff. And the small ships could just be small dinghys maybe with a fishing rod sticking out to the side to show that it's just a small fisherman's boat.