Complexes are basically a collection of prepared and secured modules that have been specialised. These assemble hulls to produce ships as per the rule book.
You can have as many ships in production as you like, but the number of hulls added to any single ships per week is
hull production limit = 2 * sqrt(hulls);
Where (hulls) is the size of the ship being built.
e.g. 100 hull ship in 5 weeks
150 hull ship in 7 weeks etc.