Is it possible that there is some sort of "register" for particular ship classes and if the number of ships exceeds the limit then things crash?

PS: Looking over in the classes you can see some other non-stock items.
Flores: This a Dutch gunboat. Flores and Soemba are added to the RNN (per Jane's Fighting Ships).
AP's: AP's enter the game as passenger liners or troopships. The liners may upgrade to troopships. Troopships may upgrade to armed merchant cruiser. Each type of AP upgrades to a different type of armed merchant cruiser with the appropriate speed, endurance, and armament. AMC's may upgrade back to troopships. I'm still playing around with that. I'm worried the AI may trap ships into an perment upgrade loop from troopship to AMC and back again.