enemy pinging goes on forever?

[sublynx]

The ship dead in water doesn't have it's engines on, but can probably hear you perfectly. He listens to you, the one going around you pings you.

1. Get away from the DIW ship. If your battery is still good, I would do this with a fast speed. It's easy to avoid depth charges, if there is only one guy running after you.
2. After the DIW ship is a long way from you - I think 1 km might be enough, but 2 would make it more sure - start losing the runner. Slow down to 50 revolutions per minute, 1 knots. You might be able to make 100 RPM's and 2 knots, depending on how good the destroyer is.
3. Don't use time compression. That makes you louder (and more visible, if you're surfaced).
4. After you have lost the ship running after you, recharge and reload, and go sink that DIW ship. It's an easy shot and Dönitz will like you more, if his orders for your time period is to attack the escorts with the acoustic torpedoes. Approach quietly, he will hear you approaching and might call the other ship to chase you again.