Late December 1939
I'm on my 4th patrol. The first 2 were in a IIA. I upgraded to a VIIB after my second patrol.
My patrol area on this patrol was north-west of England, where I sank one large freighter travelling alone. After my 24 hours on station, I moved over to about grid AM18 where I sank 4 other ships travelling alone.
I then get a report of a large convoy travelling east at 6 knots. I set up a intercept course, using what I've learned from this forum and used very sucessfully against single ships, and I reach the intercept point about 8 hours later. No convoy shows up. I dive and listen for them-nothing. Pop back up and back track down their projected course-nothing.
I figured they probably changed course. I pick off another single and cruise around the western portion of square AM for a while.
So I get another convoy contact report of a large convoy heading east. This time, I think maybe they will change course to the ESE or SE, so I plot an intercept on that possibility. Same result.

I swan about the area looking and listening but still nothing. I manage to find and sink another lone ship however.
I know convoys probably aren't easy to find(if they were, the war would be over very quickly), but I'm on a convoy route and am getting contact reports, but I just cant' find them.
I think one or more of 4 things may be happening:
1.) I'm patrolling at a point where they may be turning from an easterly course to a SE course to port and I may just need to search further west.
2.) The convoys are making a sharp evasive turn immediately after the contact report-maybe picking up the signal and turning. I dont' know if the AI is that smart though.
3.) I'm heading too slow for the intercept point. I need to plot a faster speed for the intercept and try to intercept them sooner.
4.) I'm just screwing up the intercept course. Doubtful though-I use the same process for the single ships and have only missed finding one so far.
I think I may try 1 and 3 and see what happens. I have just under 50% of my fuel left and plenty of torpedoes left to keep looking. I'm still pretty pleased with the results of the patrol so far-6 ships for over 20000 tons(and I saved the game last night on an intercept of another, to be hopefully finished off today after work, however it is pretty stormy and the seas are bad), but I definitely want more and I want a crack at a convoy.
So, does anybody have any suggestions?
Thanks.