Brings up a variety of subjects one of which is the black market in used parts. For ships, of which I have more than a passing acquaintance, they can be rust buckets in as little as five years. Tankers which are registered in the US and any coming to or leaving from must now be double hulled. The ship itself is retired at twenty.

Do they go to the breakup yards? Not quite yet. The US itself bought roll on roll off hulls headed in that direction made in France and Denmark and Russia. Spent millions refurbishing them as they had not enough to move troops and equipment to Gulf I or Gulf II. But during the down time between wars or the lulls between heavy shipping schedules in rotating divisions, maintenance was minimal. followed by a hugely expensive rush as the ship recrewed and raced to meet deadlines. - after a month or two or three of sitting

Four P's Piss Poor Prior Planning thy initials are Military Sealift Command.

Navy hulls after one deployment routinely go into maintenance for 18 months or so.

Combat aircraft seem to be an exception. But the standards there are much tighter down to and including JP7 fuel for actual combat.

MSC treats it's crews even worse than they treat their ships. Unions? That would be Seafarers...military division. The leadership is part of the socialist triumverate and works for the goverenment. Not the ships, not the crews, not the country, not the people.