There's a link to the MoBo forum in my signature. No, it's not a mod...

After you've got the single ship interception down pat, and are using the same principles to meet convoys, your next step might be to go to the Subsim Download Section and get the Lunar Phases Charts (and print them). Then you can start shadowing convoys while planning the time of your approach for night surface attack sans moonlight. It definitely gets you involved and feeling that this is more of an historical simulation.
Reverie

Good idea Reverie, must have looked past it on subsim downloads. I Like it.