I nominate myself.
U-93, early 1942 @ 80% realism.
I fought a running battle with a huge convoy that was about 40% tankers. I sink five of them, and run out of eels. I head home, and while in transit in BF, the bridge crew spot a merchant ship....
Which turns out to be a passenger liner! I dive, then steer a parallel course; thinking that I can surface and fire off a few rounds of the deck gun before she pulls out of range...
I surface, fire a few shots, and then, she's dead in the water. I pull in closer, and see that I must have scored a hit on the bridge. A few more shots, then she starts to sink.
26000 grt with about 20 rounds or so. Worth it, I think. My very first liner, too.
"I told you... we really should have gone to Mexico this year...."
Grand total for this patrol: in excess of 114,000 grt. Not bad for a type VIIc.
__________________
"Turning enemy ships into marine habitat since 1986!"
Mods Loaded:TMO 2.2, RSRDC, MaxOptics, Strategic Map Symbols, Stop The Shouting

OR:
RFB, RSRDC, Maxoptics, SCAF, Strategic Map Symbols and the sanity-saving "stop the shouting".