Reloaded the save game, fired one more fish, making four - it missed. Whiskey Tango Fox, this thing;
Is dead in the water and by all that's holy should be sunk, yet the TDC claims it's going 8 knots.
Finally got disgusted, blew tanks and finished it off with 3 shots from the deck gun.
In real life I could have sailed off and left it, if it didn't sink by itself one of the IJN destroyers would have finished it off (after removing the picture of the Emperor and possibly a few crewmen) since what's left wouldn't be worth towing home for repairs. One thing I liked about Microprose Silent Service series was you got credit for damaging ships that didn't sink, how Ubisoft could have missed that bit of realism is a mystery.