New renewable idea

Turnip probably believes off shore wind farms are designed and built by 'greenies'. True engineers only design nuclear - hence us having to go abroad for them. And of course nuclear power stations last forever.

Well maintained may well be the key point, the Nab Tower finally needed major work done when it got to over 90 years old.

Even some structures that have not been maintained have turned out fairly resilient such as the wartime anti aircraft forts in the Thames Estuary, You have the Army type ones such as Red Sands and Shivering Sands

Still standing fairly well some 70 years after being built and being abandoned after the war, some were used by pirate radio stations but their budgets did not go to any structural maintenance. One that has seen some is the Rough Tower owned by the Bates family who declared themselves an independent state back in the 60's a situation they maintain and is tolerated to this day.

Since they were built the offshore oil and gas industry has led to many techniques and coatings to protect structures at sea some of which has spilled over into other fields, The Forth Railway Bridge for example now having a main coating supposedly good for 20 years before major work will be needed again. No longer do a team of painters just work back and forth.

A life of a ship is usually set by other factors than the corrosion of the Hull exterior which is a fairly simple shape to keep coated. Replacing worn out machinery and pipe work installed before a couple of decks were placed on top can be so expensive it is more economic to build a new vessel and get what you can by scrapping the old one, and often it is corrosion from within that cause more damage , a leaking pipe from the crews urinals may start off damage that never really gets fully repaired due to awkward access or lack of crew to do a proper timely fix.

G.Harman

It is likely they would be floating anyway. Just vaguely anchored to the sea bed.