I have not seen this written about, and I have used it quite often since I discovered it. Tell me what you think.
What I like to do, is usually take an hour or more to set up a shot, get in an absolute dream position, and fire my first torpedo. Then I watch the trail as it goes scurrying off in some direction nowhere near the target. THEN I check my manual settings.
Now personally, I haven't had much luck with it, but I thought compelled to pass this along, as it seems like an important tactic. I've went ahead and dubbed it "the Flopper attack," in case it gets put in any attack manuals.