Good memories, those.
Well, here's what my successful Shark track looks like so far - you can probably tell exactly what I'm doing here. It works, but not without those max speed dashes to close the first 5k yards, with pings for every 1000y travelled to refine the contact - and between them, I still have to be blind. If I wait too long, the sub starts hiding among all that shrimp, and things get very messy unless you have it on HF to start with. You can even see one false return going further south that, had I not quickly sorted out, could have sent me tracking the sub down the wrong path.
I wonder if I should just trying a bit patient and dash at, say, 20kt instead of the full 30...