Detection range of destroyers

[Scape]

I know you can see it mapped when your surfaced and looking on the map but what is the detection range of the destroyers for surfaced, decks awash, P depth, 60m and 200m and crush depth? I know there is some randomness but I have been using 1.5km range around them and using that as a rule of thumb and not going above 2/3rd speed and once inside 1.5k I cut to 1knt.

Greed an impatience kills me a lot but this will allow me to set better expectations.