How does the game assign ship damage to a torpedo hit?
Using both auto-targeting and the O'Kane method, I have usually had success by firing the torpedoes* in quick succession, reckoning that they will impact very close to one another, causing maximum damage, but occasionally the ship will become a floating or limping hulk, failing to sink till a final fish or deck gun HE rounds send it to Davy Jones' Locker...
Seems like the game takes into account where the fish hit, or throws in a random "don't sink" command??
* Generally, I use these to attack merchants
1 torpedo for small ships
2 torpedoes for medium ships and passenger liners
3 torpedoes for large ships