system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If "ghost" ships are set to be scrapped, how do they manage to float around the ocean for so long?

I saw the recent post about the ghost ship full of rats that is floating around the ocean.

If this (and other) ships are still able to float for seemingly long periods of time, why are they being scrapped? Wouldn't it be cheaper to fix them than it would be to build a new boat?
gpt
The ship is able to float.  Doesn't mean that it can do anything useful.  A ship can float (to some extent) with some fairly large holes in its hull, as long as it is properly compartmented to contain leaks.

The engine may be all but useless.  In many cases, it's easier and cheaper to replace the entire vessel than replace the engine; the design may no longer be considered efficient enough, spare parts may not be available, etc.  Changing a small part of the engine system may require larger structural changes, as shafts and gearing need to be moved.

Basically, there's a lot more to a ship than being floatable.