the same object?

If I had a ship and replaced one of its planks is it still the same ship? what if I replaced two planks? what If I replaced half of the planks or all the planks is it still the same ship? What if over time I replaced all the old planks over time but I saved all the old planks and but I kept all the old planks and then put the planks back together to make a second ship. Which of the two ships is the original ship the one that was first built or the one that is made up of the original parts?

 

It wouldn't be the same ship. When you replace one plank with a new one, it is technically a different ship. It's no longer the original. The only thing that stayed the same was the name of the ship. In the case of replacing all pieces of the ship and using those old pieces, they would be a mere shell of it's former self. The new ship would be a Mark II, mostly on paper unless you specifically add it as part of the ships name.

This can also be said for all of us. Over time, we ourselves are not the same person we were when we were first born. We are constantly shedding dead skin cells, leaving the only thing left of our past selves as memories. We have been (naturally) altered so much, that we technically don't have the same body anymore. Within 1 month, we already have a new coat of skin.

 

Replacing the planks with an equal plank would probably make it the same. Replacing the plank with some fancy space age anti-torpedo plank would be changing the ship. I think if it actually changes some kind of specification it would mean it changed.

Or am I being dense and should dive into this deeper like Vashnik said?
Examples with glass come to mind.

 

You can replace as many parts of a ship as you like the only thing is when you replace the keel of the ship it changers its not the same it may handle differently. So replace all the planks and decking its the same ship replace the keel its a new ship
One Piece episode 233