escort tactics

[navy_ae]

ok heres the situation have a convoy with escorts closing on but going to the north so im making a surfaced at night flank bed to the north then plan is to drop to periscope depth and sit there like a hole in the water ... do the escorts ping away constantly or only if they detect a sub ?? plan is to then shoot a spread at merchies shoot 4 mk 27s out the stinger and run like hell and go deep