I have a video going up on my channel on Saturday, April 12, where I somehow manage to evade three torpedoes (sorry if you watch my videos and I'm spoiling anything! oops)! I couldn't believe it either haha. Alright, so I learned this technique from my friend and it has been working rather well for me in stock Dangerous Waters.
What you want to do is figure out the bearing of the torpedo through whatever means. You can do this before or after you drop counter measures, but it's probably better to do it after you drop counter measures (I'll get into why in a second).
After you drop counter measures, you're gonna wanna set two waypoints. The first waypoint should put you about 1-2nm behind your counter measure field. By 'behind your counter measure field', I mean have the counter measures exactly between you and the torpedoes so the angle between you and the torpedo with respect to the counter measure field is 180*.
After that, you want your second waypoint to put you on about the same course as the torpedo, which should keep the counter measures between you and the torpedo. If all goes well, you should be hearing sonar report a loud explosion very shortly and you'll have successfully evaded the torpedo
This has been working very well for me, let me know if it works for you!
EDIT: I should note this is for a torpedo on SNAKE search pattern. If a torp with circular search pattern (usually dropped in the air from something) lands within acquisition range of you, I'm not sure there's much that can be done.