I've done some good work in the Java sea. Took out a whole convoy of 6 ships and a pair of Destroyers for good measure early in my current carreir (currently my captain is in Aug 44). High speed surface attacks are the key here. Also if you incounter a very well defended conovy don't attack right away, shadow it until it gets to deeper waters of the South China Sea or Celebs Sea and make a dived attacked.
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