Lfn - Sub Mission #5

Stuck on this at the moment. The closest I came was when I pivot to port at flanking speed, knock out the DE's, then work on the Patrol boats. I've killed them all once. When I killed them, I only had a few torps left so I surfaced and headed for the oilers. After sinking three, my hull was almost gone from being hit by deck guns and the depth charges from a patrol boat that got to close at the start (got him with my stern tubes and dived, surviving with about 1/4 hull left). Anyway, so i'm 3 oilers down with 1 to go and nothing left on my hull. I have no torpedoes so I try to get out of firing range. Alas I surfaced to early and died when I was so close to victory. Patience would have saved me.