In an Old sub game I had I came accross two battle groups ( one carriers, one BB's with with only a couple of escorts each) in the pacific (was playing american V's Japan). Sank all the carriers and crippled both battleships. I then surfaced and started using my deck gun on them. sank one with 15 rounds left. I then moved on to the last BB. Used all the deck gun rounds, then all the heavy flak, and was down to the last 6 rounds of light flak when she gave up the ghost
The tonnage from that patrol was something to remember!
Something in the order of 250,000 tons!
I'm the tonnage king of the world!!!!:p