1941 Escorts asleep?

[siber]

Ok, let me walk you through the situation, because I'm worried that I've 'broken' SH3 somehow. I'm running SH3 updated to 1.4b, and have then installed GWX 1.03. The only other mod I'm running is the Torpedo damage final mod.

Sailing a type VIIC in 1941 loaded with typeIII electric torpedoes, I keep intercepting convoys. My general use tactic is to come to a stop at periscope depth at one of the leading corners of the convoy. Normally, I can hear an escort in the lead, and one out to the left/right side (depending whether I'm positioned at the left/right corner).

As the lead escort comes past my bow, I move (on silent running) forwards towards the centreline of the convoy, looking for the juiciest targets. As I'm at approximately 90 deg. to the convoy's path, the torpedo solutions are simple if i can get the range/speed accurately. Generally I can hit more than one ship each time.

At this point, with the stricken ship sinking, I head down to 150m depth at half-speed (figuring that the convoy now knows there's a sub about) before cutting back to silent running again and heading for one of the rear corners of the convoy to escape. I sit hesitantly, awaiting the depth charges that I've been used to in 1939-40...

But they don't come. The first time this happened, I congratulated myself on such a stealthy attack and evasion. Then it happened again. And a third time. Three times now I've attacked different convoys, sinking about 8 ships, and the escorts haven't even blinked! No rushing to the scene, no spurious DC attacks in the hope that I'm still where I attacked from, not even a change in speed or course...

The only thing I can think of that's changed since 1940 is that I've upgraded from a VIIB to VIIC sub, and that I now solely use type III torps (following an unpleasent incident with an aircraft carrier), instead of type I steamers.

Is it me, or is something not right? Perhaps someone who knows GWX can comment? Is it broken, or am I now the best Kaleun in the sea? I'm reluctant to believe the latter...