Quote Originally Posted by ReiseReise
You must be mistaken Monsieur.
Ports (Port, Shipyard, Dockyard, Naval Drydock) are mainly for building ships. They also increase trade as I mentioned. Top 2 levels are only available in castles.
Sea Trade (Merch Wharf, Warehouse, Dockyards) increase trade and also the number of trade routes. Require Port and only available in cities.
No I am not. This has been dicussed before in another thread. After some testing it came out that ports etc. gives the most increase to sea trade.