I didn't say it's not understandable, just that it breaks down - i.e. doesn't apply anymore. The point of an analogy is to point out how our intuition tells us

I didn't say it's not understandable, just that it breaks down - i.e. doesn't apply anymore. The point of an analogy is to point out how our intuition tells us it's the same boat, despite having no parts in common with the initial boat. As other comment mentioned, if you keep the sails and rebuild a new boat around it, no person in their right mind would feel that it's the same boat. It's very clearly a new boat, and the analogy breaks down.