Hi Vendor,
Try the area BF11 - BF14 , its the sector just south of Ireland.I usually patrol a 200km corridor through this area if ever I get posted nearby,and my current patrol (which I am returning from) I bagged 7 merchants for just under 50.000 tonnes in that sector.
If ever you get stuck for deciding on where to hunt always try and identify chokepoints for your kills,and ideally in open sea/ocean . Naturally the Gibraltar strait is possibly the most famous chokepoint on the map due to the very narrow opening,but is also a death trap for the unwary...be warned
If you want to hang out around there,just draw a line bearing west from Gibraltar and park anywhere where the sea gets deeper,you should still detect MANY contacts as they come and go!
Another good spot is the chokepoint between the Shetlands and the Faroes? (NE of the tip of Scotland) , lots of cargo passes through this area.
And if you like sinking oil (which I do!) and you are in the vicinity don't forget the various chokepoints near Florida,many tankers usually pass through that area heading north from S America.I remember nailing loads of tankers once in an old career out there.The only problem is,it takes bloody ages just to get out there!
Good hunting.