ideally, i want the DD to come at me from behind, slightly off to one side
say, bearing 160. only possible if you already turned away from him after the previous attack.
sonar guy tracks him when he comes back, as he starts to close in i order a turn the other way (in this case to starboard) and change depth at least 20m
all this still on silent running so the changes will not have much effect yet but they are 'pre-ordered'
then, when i am pretty sure that he has me (the ping-ping or i made a lot of noise earlier) i'll start speeding up when i can hear him from inside the boat
when the depthcharges fall i'll get to flank speed and that means my 'pre-ordered' evasion manouvre is executed swiftly
then silent again
the important thing is to only actually do this to avoid being blasted to shreds, so only use flank speed if the depthcharges are about to nail you (as far as you know).
if there's more than one escort, you will give yourself away and you'll have to keep playing that little game over and over
i often find that escorts (even multiple, even in 1943) will spend a long time blasting a certain spot where you were some time ago. if they didn't actually nail you with ping-ping and if you think you didnt make enough noise to be picked up passively... they may not actually have you and they may simply do an attackrun on your last known location from the previous run. it will appear as if they are coming right at you but in fact they're not
if they trick you into using flank speed without good cause, they'll re-acquire
at some point, they WILL temporarily lose you. the trick is to figure out when that is
steel nerves and a good sonar guy are required
god how i love that cat and mouse game