When you get a sound contact, figure out which direction the convoy is headed, and stay out of range, change your course and head flank speed to position yourself in an area where the convoy will pass. Once you get a visual, that you are indeed in the path, go periscope and setup in a spot to ambush. Once you get in good position, if there is an escort in the lead, go silent and dive deep before he gets your visual. On his sonar trace passes you, come back up to periscope and commence ambush, with full fore and aft salvos.
My favorite common ambush spot below ..
key: => (merchant) -> (DD's) ^ (me)
HTML Code:
<pre>
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=> =>
=> =>
=> => ->
^ (DD that passed overhead of me)
=> =>
->
</pre>