This is an absolutely fantastic concept. It brings back good memories of sailing the Great Sea in The Legend of Zelda: The Wind Waker and hauling up treasure using the grappling hook. I yearn for another high-seas treasure-hunting Zelda or Zelda-like.
I will say though, that I think undocking the crank and using it to raise and lower the grappling hook might have been a more fun and interactive way to find the treasure tbh. Controlling the boat with the crank felt a little off to me personally. But otherwise, fantastic job, lovely stuff.