Even the yachts at Monaco are working, and serve a purpose. Even if they don't go to sea, their owners entertain guests on them, so they are serving as high prestige private hotels!
At sea, there is always a certain amount of rust on metal ships after a few weeks. It is possible to keep painting them so that they look perfect (even if it is painting over the rust).
I do put rust on my models from time to time and I will admit that if I am intending to "weather" a ship, I do not put the same effort into the detail, but use the weathering to cover up slack workmanship. Here is an example, a shipwreck on the Skeleton Coast of South West Africa.
Bob
