Request tactical advice on convoy approaches

[PacificWolf]

My tactics is:
1. Swimming at the surface and searching for radar (if You had any) or sonar contacts.
2. when i have a contact i slow down and track this bastard and plant his course on the map.
3. When i had the course im going to set my position within firing range and go to periscope depth, go to silent running (strangely even the merchants can hear You so keep that in mind)
4.When i identify that the ship im about to engage is hostile I Fire torp (if thats nessary, because if the ship doesnt have deck gun i surface i engage it with my gun to save the torp).