Really really Skilled Aux Subchaser (TMO)

[Dignan]

Someone tell me if this is normal.

I'm in a campaign and got pinned under by a lone auxiliary subchaser in the east java sea. (the how and why isn't important ... Ok, I was trying out the Dick Okane targeting method and got overzealous with TC and before I realized I was tracking a subchaser the ship detected me.)

I'm in a Tambor class, running TMO and RSRDC. This damn thing has had me pinned under trying to evade for hours. I go silent, I change depths I "charge and coast" and have gone as deep as 410 feet. Even at that depth at zero knots the chaser still knows EXACTLY where I am and keeps dropping depth charges. I've even come to periscope depth a few times to try to get off a "down the throat" shot but he's always on me so fast that the torp won't arm in time and back down I go.

I'm not knew to SH4 and have had great success evading much more capable escorts so what am I doing wrong here? Is it TMO? Is it a fluke subchaser with really incredible sensors?