In a bind - need strategy help!

So here's the deal: 1943, returning from patrol north of England. Just bee-lining around England to get back to Bergren, minding my own business.

On my current course, I miraculously pop up in the middle of a British flotilla - only 700 meters from a few cruisers, 2 or 3 Nelson's, and a King George Battleship. The problem is I only have 2 torpedoes left - one in a fore tube, one in an aft tube. I really want to bag that KG battleship.

I've reloaded the save and few times and have tried a few things: I've hit the KG battleship in the rear thinking to knock out it's propulsion and leave it adrift, then line up the aft tube with a shot to the center to sink it. That didn't work because the hit to the propellers didn't do anything, not even scratch the paint.

I've also tried to line up the aft tube first (before being detected), trying to sink it in one shot, or a second with the fore torpedo, but the first hit just sends it running and I can't turn the boat around and catch it with the fore tube in time.

I've also completely missed a bunch of times because as soon as I fire, it turns and runs.

What would you do?? I've even looked through the game files to try and add more torpedoes to my save (hence, cheat) but I can't find where that torpedo complement data is saved. HELP!