Shipyard will not unload cargo from the ship unless some of its cargo gets removed first. That can be done by building external storages for the products stored here.
All the cargo that is temporarily stored in the shipyard. When the shipyard gets too full it is unable to unload more cargo from the ship. Trucks always actively remove products from the shipyard whenever there is space somewhere else.
Serves to refuel, repair, and modify our ship. Also handles loading and unloading ship's cargo. If a truck happens to have some cargo that cannot be delivered anywhere else, it can be delivered here.
TassoleHoff