[Hooston]

I'm afraid GWX is very hot on use of passive hydrophones by escorts. This is their primary means of getting contact. If you shoot a steam torpedo, go fast or reload you will be picked up from several km away.

In game the escorts will head stright for your location when you hit something, so you may as well go fairly fast at first (I use ahead 1/3) to: get as far away as possible, dive down to 140m+, point your butt at them. When the escorts are a few km away switch to silent running and go slow. If the wind is 4m/s or less slow means ~1 knot.

If you are being pinged with a high pulse rate wait for the escort to speed up on its attack run and the pings to stop, then go fast and change depth by ~40m. The speeding up is realistic, but game ASDIC seems to pinpoint your depth very accurately so a depth change is also very effective.
Go quiet again once the charges have exploded or the escorts will pick you up again. If they do not detect you they will continue to attack the last known position for about 30 mins. In real life they would go slow and sweep for an ASDIC contact for much longer until finally dropping a charge for "scare effect" before moving on. Late war, they would hang around for a whole day!

I recently watched "The Cruel Sea" again. Being released only 8 years after the end of the war, the historical accuracy was really good. The corvette (and later frigate) was banging away on ASDIC all day and passive detection seemed a secondary feature.

I've changed to NYGM recently and it feels better to me. Early war, creeping away appears to be more effective and you can reload and go ahead 1/3 if the escorts are at medium range.