Allies sonar is infallible, they could find a IIA 800 meters down (pretending it could successfully survive the depth) on the bottom, in a underwater canyon; they'll still drop charges on you with sniper precision (though the charge would explode short, if it could deeper you'd end up dead fast). Escaping from ships once they have you targeted is difficult and enormously time consuming.
Shallow water can be dooable if there's at least 25-30 meters or total depth. If you're lucky enough to be in a storm it raises your chances. Once the boat accelarates punch to flank and hard port/starboard to get clear of them like you normally would. Cut the engines short of the last one or two charges going off them move ahead slow, if you're perpendicular and lucky you might make enough distance if he circles away from you. Try to be as close to underneath the ship as possible so charges generally won't explode close enough to cause major damage.
If you're lucky enough to be close to shore or a wall and the total strip of land only leaves a small amount of water to maneuver in you can sometimes get the destroyer to blow itself up. Doing so is really tricky, you need to get the escort to start its run on the short piece of land where it doesn't have room to accellerate after its dropped its charges, once it does its still to close and blows itself to pieces.
|