https://features.propublica.org/navy-accidents/us-navy-crash...
A quick break down:
* chronic understaffing - ships have a certain number of billets. 7th Fleet in particular has been sending ships to sea without all their billets filled, particularly in the junior officer ranks. This means that you're not just doing your job, but also doing the job of the person who isn't there
* deferred maintenance - there's a lot of redundancy on these ships (warships tend to like that) so if something breaks it's not catastrophic - you can just use the back up until the sophisticated main system is repaired in port. However, after years of "just using the back up," those systems are failing, and HAVE to be repaired, often at sea. So, in addition to your job, and the job of the person who isn't there, you might also have to go help fix the HVAC or some weapon system or what have you.
* aggressive operational tempo - the Navy has said they need X number of boats to do the tasks required of them. They are funded for/have X-N boats. In order to make up the deficit, the ships they have are deployed on longer cruises, with less time to fix things. This is the core issue that's the root cause of these other failure cases, in my opinion.