It's pretty obvious...the enemy has a sonar- and a hydrophone-guy.
One pings you (loud ping=sure lock), and the other listens for you.
Hence the 1kts-maximum, at critical times....on silent-running.
To cope with his sonar, you have to pay more attention to depth- and course-changes.
Mann the hydrophone yourself, and speed up when he speeds up (he's going to depthcharge you)...slow down again, after the last DC explodes.
When you hear his engines stop, you stop as well...he's carefully listening!
Try to make sudden turns on speeding up, set back to 1kts, and use the decreasing-speed time to change depth again.
Keeping a low profile is probably the best thing anyway...keep them on your six!
It's a tedious job, but you can save your boat.
