Don't forget: SH3 Commander randomizes the depth range of enemy sensors to simulate thermal layers. It could be that the escorts aren't hearing you because you're under this artificially created layer through SH3 Commander.
Also... Depth charges automatically Unspawn at 300 meters, if you manage to get to 305 meters the depth charges won't reach you HOWEVER the blast wave if one blowing up at 299 meters will get you
__________________
|