IMHO, a typical ASW vessel is a giant island of electronic and acoustic noise-maker on the surface. Radar emission can be detected at great distances, sensitive sonar systems can estimate the course. But the worst case scenario for a submarine is to be detected within the engagement limits of this vessel. You can detect it, but the destroyer/frigate dominates the area. Getting into torpedo range is a very risky warfare under any circumstances. If the submarine fires a torpedo,conventional type or not, it will become predictable at that moment, am I wrong?Supercavitating torpedos are the loudest mfers under the sea. Any competent vessel would instantly know where it is and where it's coming from and deal with it accordingly.