A little background - I'm resuming my first career war patrol after starting it around 6 months ago. I made a night intercept and attack on a small convoy of two large transports escorted by 3 destroyers. During the attack I sank one destroyer and one transport, but only managed to damage the second transport before I had to go deep and evade the remaining destroyers. About two hours later at what I thought was a good distance away, I came up to periscope depth to take a look. They were circling about 4500 yards behind, still dropping depth charges and firing what seem to be flare shells (though in one ridiculous barrage one of them fired something like 20 of them making a gigantic glowing blob in the sky). I went back down and continued running silent for a while and came back up for another look. The destroyers were barely visible in the scope at high magnification, too far for range to display in the position keeper (yes, I'm using auto targeting. Honest - I do plan on getting a handle on manual tracking and TDC, for now though I want to work on getting into good positions and running intercepts without worrying about it - for the moment my tracking party is really good
). At this point I cheated a bit (or a bit more for those of you who would say I'm already cheating with auto targeting) and went into free camera for a better look. One of them was still milling around in circles well astern, the other was well on it's way heading back to the damaged transport which was by now a distant fire and column of smoke on the horizon.
It looked like I had pretty well shaken them off, so I secured from silent running and battle stations and went ahead standard to open up more distance but remained at periscope depth. I don't know what the actual distance was to the nearest destroyer but I'd guess at this point probably at least 6000 yards. Simulation time was around 3:30am, so it was totally dark and there was no moon. A few minutes later I raised scope again and was more than a little surprised to see one of the destroyers dead astern heading right for me at 33 knots! Swinging the scope around revealed sure enough the other one was coming on full speed as well, but at a greater distance since it was almost back to the transport before turning around. I figured at least the one dead astern would be a candidate for a down the throat shot. I set a stern torpedo for 6 ft, high speed, magnetic exploder. I think he slowed to something like 20 knots at some point, I fired when the range was around 1900 yds still bearing exactly 180 - the torpedo would close at something like 65 knots adding his headway. It hit with a nice big splashing explosion right on the bow, but all it did was cause him to slow and turn momentarily. Otherwise no damage. Not sure what to make of that. Took another shot and missed as he stopped. So I dove deep and called it a night and saved the game at the start of what looks like will be another slow evasion session. I haven't even reached my patrol area yet and only have 8 torpedoes left (but thus far have bagged 3 big transports and a destroyer).
Sorry, I just noticed how long this post is getting - so my questions are what's a general safe distance to pick up the pace while submerged to put some more distance between you and the destroyers? I won't surface inside of 5 miles - but how far can they hear me while submerged beyond minimal speed? What probably gave me away - too much noise going ahead standard or would securing from silent running be enough? There's NO WAY he could have spotted my scope in the dark at 6,000 yards. Are "down the throat" shots a crapshoot, assuming you even get a hit? Should I have set a deeper depth using the magnetic exploder - I set it shallow since it was a destroyer? It appeared to explode right on target, and thus far in my experience one hit on a destroyer is usually fatal. All this one seemed to do was get the guys on the forward deck wet.