Cool, I hope I make it to '41 then. Haven't survived 1939 in 2 careers so far.
My last patrol saw 17,314 tons from 3 ships. I gotta be extremely selective with 5 torpedoes onboard, so I've let quite a few small ones slide by me, gritting my teeth because the flak deck is always awash when I need it.
Good news is, all 5 shots were hits this time. Full load of fast steamers makes me happy. With my style of approach, I could fire flashing disco balls with an air horn attached...nevermind the bubble trail. There's no getting around a 40kt shot from 600m headed straight at a barn door, unless their deity of choice manages to miraculously lift their ship out of the sea. (And yes, this is possible. I watched a Granville Freighter catch some X-Games air off a wave, it's keel about 2m completely above the surface.)