Ducimus,
Thank you very much for bit of information. I was just wondering why the escorts were pursuing me when historically, the British didn't know how deep U-boats could go until they captured one. Using this logic, I figured that suddenly stopping both maneuvering and engines immediately after a depth charge attack and drifting to the bottom would be recognized as a "kill" (though I was sorely tempted to blow some ballast to give the ruse a greater effect). One never knows how the "logic" of the code is written until one asks.
...or until a generous person such as yourself offers the information. Thanks for the enlightenment!