This has already been reported but I think its important to mention it's still happening:
AI keeps building and scraping ships... this is a printscreen from my 1890s campaign as USA, in abril 1910 (20 years in) and look at the fleets the countries have... only Italy seems "realistic"... and no, I haven't wiped out their fleets, I've only been at war with Spain (goodbye) Japan and China... This is a major hindrance for a fun/realistic campaign
Hope this gets fixed soon, been loving this game, have hundreds of hours playing and think that it has HUGE potential, once the quirks/bugs are ironed out it will be THE naval strategy game of the century