Passing thermal layer and DC's attack?

[Psycluded]

The strangest thing happened to me this morning, actually. To preface, I had already dove below 250 ft in the area to find where my chief of the watch called out "passing the thermal layer", so I knew where it was, in general. My plan, as is usual, is to get within radar contact range of the convoy, so I can get a snapshot view of the formation, how they're manuvering, if at all, and the direction and speed of travel.

This time, their direction was northerly, so I submerged, sprinted north and placed myself perpendicular to their track and called an all-stop about 800m from where I knew the closest freighter would pass. I was at 250 ft, in silent running mode, watching the auto-updated map as my sonarman called in the contacts.

The first attack went perfectly. With zero forward motion, I hovered up to periscope depth when the first freighter's stern passed parallel with my bow, popped the attack scope out of the water and did a quick 360-degree scan. The closest escort was the starboard side escort (looking from the convoy's point of view) and he was astern of me at a range of about 1000 yards, off on a random search.

I lit off all 6 tubes at the juiciest targets and immediately dropped the scope back down, dove to 250 ft and moved northwest (underneath the convoy) to reposition for attack. As I was passing the first freighter (underwater mind you... he was in two pieces), I heard depth charges go off behind me, so I hit F11 and went out to look. Sure enough, that DD that was DCing where I had been, or near enough to it.

The only thing I can think of, since I'd never seen this happen in SH3 or SH4 so far, is that he must have caught me before I passed the thermocline, and that the layer in that area must have created a convergence zone, causing him to misinterpret my location.

I gotta wonder if these kinds of advanced sound behavioral characteristics are modeled in SH4. I mean, I know how to use them from playing Dangerous Waters, but if it works in SH4 as well? It would explain the gross range mis-estimations my sonarman gives me from time to time (docked ships whose range estimates put them cleanly on the beach, etc).