If in the course of a long journey you replace every part of a ship can you still call it the same ship.
What if the ship has the same keel, sidewalls, masts, compass, and rudder? The rudder pole has been replaced by a wheel. The sails have been replaced with sturdier material, and a lateen sail added. The old wind-worn masthead has been refinished and polished up. The once completely open cargo hold has been compartmentalized for more effecient stowage, and a loading crane has been added.
The ship sails to the same ports, carries much the same cargo (plus some newly discovered spices), and many of the same old passengers board the vessel.
Some of the old passengers look at the ship and say, "The old ship is better than ever." Some of the old passengers look at the wheel, lateen sail, and pretty masthead, and say, "What happened to the old ship?"
"This is the old ship."
"No, it's not."
"Yes, it is. Look at the structure, frame, hull, etc."
"No, it isn't. Look at the wheel, the sails, the crane, etc."
"I've been sailing on this ship for 25 years, it's the same old ship."
"Sorry, but to be honest with yourself, you have to admit this is a different ship."
Quasqueton