On my first patrol in AN47, I couldn't find anything at all in that grid.
I remember reading that Hartlepool was a port easy to sneak into, and it was.
I was literally 300m away from the stationery ships, I was at periscope depth but I did have my periscope up the entire time and the the lights were just loking at me
I managed to sink all 3 ships, one being a T2 Tanker, the other a C2 Cargo and the other a small merchant if I remember correctly. Was proud considering I'm new to this game
My battery was low though an oxygen reserves getting low, so I had to surface in their port, still not noticed somehow

maybe it was the weather? It was foggy and stormy.
5 Mins later and a warship just rams into the side of me and sinks me