Here’s one thing that no one ever mentions about building vs upgrading aircraft carriers – you won’t hear this often. One really big reason why the US continues to build supercarriers is to maintain the knowledge to build them.
Aircraft carriers are still the backbone of US Naval strategy and probably will be for a long time. In order to be able to build them when they are needed we need to ensure that younger generations of shipbuilders gain the knowledge that puts these things together.
Constructing a structure as large and complex as a supercarrier requires much more than engineering drawings and a few tech manuals. There are thousands of things that shipfitters learn and pass along during the building process that never gets written down.
It’s often referred to as “tribal knowledge.” Foremen on the job for USS John F. Kennedy today were probably apprentices when the last of the Nimitz class ships were being built. They bring all that knowledge forward.
If you think this is exaggeration just look at NASA. They want to go back to the moon but rather than build a new Saturn V launch vehicle and Apollo capsule they are designing, engineering, and testing a completely new platform.
Obviously, part of the reason is new technology, but the other reason is that Saturn V and Apollo would be very difficult to resurrect. We still have all the engineering documentation, but everyone who built those items are long dead or long retired.
All those little tricks like how to wiggle this weirdly shaped component through this mess of other components is gone. Most or all of the machining equipment is gone or rusting away.
All of the software components are in formats which can’t be read unless there’s a compatible machine in a museum somewhere. IOW, we just can’t build Saturn V/Apollos anymore.
As someone else stated, long service times just eventually catch up.
But you also have to look at the type of ship. Battleships, such as the Iowas, are built around their guns. Being that they were already fast even by modern standards, the ships were just setup for a long life from that. The guns didn’t change, they were the same type of guns since Iowa first launched.
What changed was things such as radar, plotting, fire control, etc. All of which is fairly easy to upgrade when compared to what carriers need.
Carriers are built for aircraft. Aircraft get bigger, faster, and heavier. Because of this, eventually you are going to reach the limits of what the carrier can do. This isn’t to say carriers are more limited, Midway served from 1945 until 1992, and wasn’t struck until 1997. She went from 45,000 tons to 67,000 tons by the time she was mothballed.
Obviously they viewed her as vital. So there are always upgrades, and with the new planes that can take off without a runway, ships like Midway could be used again if given a new, reinforced flight deck. But after all of that, time takes it’s toll. 50 years is a long time.
You can make the argument “Well, the last Iowa wasn’t struck until 2012”, but the fact is that Battleship Iowa was LITERALLY the last battleship in the world that was still being held by a navy in either mothballs or active duty.
You can also make the argument that the US Navy retained callback rights on those old ships for a long time (they may still have it, I don’t know), but the fact is that we don’t worry about that with old carriers because we HAVE carriers, we don’t HAVE battleships floating around in active service.
So part of the reason the Iowas received refits and were kept around was because they were the last of their kind. We don’t have that problem with carriers. We have those.
