Any time Alex, that's why we're all here. To help each other
One thing to have in mind here. Weather conditions affect the sinking conditions. If the seas are rough then the ships will sink faster. If the sea is calm they might actually get away with a big hole on their hull. How many torpedoes you will fire depends on other circumstances. For example in a convoy you want the ship to sink asap so you fire as many as you need to bring her down. In a situation where the ship is alone without any escorts you can afford to be economical and hang around for some time.
Good Luck
and if you need any more help give us a shout
