I've come to the conclusion it is better to build tonnage capacity first, and then add slips rather than the reverse.
Here's my reasoning.
You want a yard capable of building 9000 ton ships and have 5 slips. If you build the slip capacity first, building up the tonnage takes a long time, a time that the yard is idle. If you build tonnage up first, you'll only be idle until you hit the tonnage mark. After that you can add slips (which will take just as long as adding the tonnage to a fully "slipped" yard), but you can start building ships right away.
