Do you want to be certain that an ship is in a certain area when they do an announcement? For example, because they first have to pass through a lock or bridge? If so, set up a geofence (zone) around the terminal. If the ship is located outside of this zone, they are automatically refused.
Using the Geofence module you ensure the correct announcement location (with a view to demurrage) without the need for a check by the loading master. The Geofence module operates on the basis of the AIS module.