In particularly shallow water I've often evaded being sunk because the DDs almost blow their sterns off with their own depth charges. I believe they have set the timing much too early and soon enough the DC sailors are flying through the air on their way to heaven
If they survive, they continue to drop non existant DCs and the DD is pretty harmless after that. They still have to be shaken off though in order to surface. BTW this is with GWX.