Right now I feel that building super shipyards is largely a waste of resources because you can only built 1 ship at once, which means that if the production ability of a shipyard is greater than the cost of the ship you just waste your production. It should be possible to produce more than 1 ship each turn. So if your shipyard has a production of 100 and a ship costs 50 production then you should be able to build 2 of them at once.