How to evade warships?

[Luftwaffles]

Greetings Kapitans!

I usually drop a decoy, throw it into forward 1, and scoot out.

But what are some legitimate ways to evade after you've been discovered? Also, what about in shallow waters?

Thank you!

[SpaceBikerV]

In shallow water, you shut off everything noisy and sit still at the sea bed. It's highly likely they won't detect you. I don't think I've been detected this way

In deep water, you can go beyond safe diving depth and hit the "shadow zone", where sound doesn't travel to the surface effectively. You risk imploding if you stay too long, though.

Both of these is mentioned in the 1943 Uboat handbook, i think

If i use Bold decoys, I usually turn 180 and put the speed on max. A combination of the decoy and the depth charges makes it so that they cannot hear your for a short while.

[No Toilet Paper | Boy]

It matters how gamey you want to be. You can survive depth charge attacks from multiple ships by changing your direction and speed so that you dodge their attack runs.

As a general rule keep your uboat as quiet as possible. Blue light, manual steering (not electric), Gyrocompass off, avoid loading torpedos (unless essential) etc.

Seabed 30m-180m: Keep it on the seabed, no speed, no sound. They should not be able to detect you.

Seabed 180m+: If they are within Sonar range then you have to change your direction, speed and depth so depth charges explode above or beneath you.

There is a region that if you go really low they cannot detect you from Sonar. However it's so low that you are going to let leaks. Leaks at really low level are real bad as even if you fix them quick you are not able to pump out much water due to the atmospheric pressure.

If the seabed is 300m+ then after a bit of water you will sink until you implode.

Enemy Merchant Ships:
You an also sail under enemy ships. The escorts can't do an attack run and I get the impression the enemy ships sound and sonar signature somewhat hides your own.