Yeah some depth charges were certainly headed my way after that one
My first attack on a freighter resulted in my first salvo missing just astern, let the freighter head on, surfaces and ran ahead for another shot, this one I really messed up and my torpedoes headed parallel to the target. My mistake this time was that I didn't re-send the range/bearing info when I was in position with the preiscope pointed at my aiming track.
Ran ahead again, third time lucky, lined it up and slammed three in to her.
The next freighter I hit first time no worries, I've got the steps down pat now.
I highly recommend everyone go 100% realism, it does take a little to get your head around the attack procedure, but it is pretty simple, and very rewarding.