Create a convoy from the sea map

 

If you order a new ship in a town without an office, you have to visit the town with a convoy to create a new convoy with the new ship.

Hunt pirates with patrol convoys

 

Town patrol convoys can be used to hunt pirates.

Convoys and sailors

 

From time to time one has to disband a convoy, to prevent losing your sailors, this should not be done in all towns.

Emergency repair

 

A sea fight might result in an emergency repair that will block your convoy for several days.

Trainer

 

The trainers in Patrician IV seems to be bound to a town.