R.I.P. Scout26
ARA San Juan was a TR-1700 boat, not a Type 209.https://en.m.wikipedia.org/wiki/ARA_San_Juan_(S-42)
It's not just hull life that is a factor. A submarine is an incredibly complex machine with a huge number of big moving parts. 3000 PSI hydraulics, 4500 PSI air systems thousands of valves for air water and hydraulics, hundred of hydraulic rams, miles and miles of piping, miles and miles of wiring. All of it subject to high stress on a routine basis. The boats I was on are pushed hard with an optempo that will wear out both machines and men in short orderBoth of the boats I served in were getting old by the time I got to them.The USS Haddo (SSN-604) had already been in active service only a few years less than I'd been alive. When I got there it was a tired boat ready for overhaul. I rode it through the yards at MINSY returning to the fleet in 1984. She was Decommed in 1991 with only 26 years active service. I had a chance to talk to a couple of guys that were on the decom crew, it was worn out.https://en.wikipedia.org/wiki/USS_Haddo_(SSN-604)The USS Flyin Fish (SSN-673) was a whopping 6 years newer. I got to it fairly fresh out of an overhaul and rode it on 2 major deployments. Even fresh out of overhaul *expletive deleted*it was constantly breaking. Mostly it was little stuff but there were a few sphincter tightening events. It was Decommed less than 4 years after I left. It too was just flat wore out after 24 years active service.https://en.wikipedia.org/wiki/USS_Flying_Fish_(SSN-673)There is only so many times you can compress a hull. And yes when you take one deep the walls do close in on you. I've seen the old string between the frames trick many times.