I implemented the changes suggested by Aanchor above with the exception that I also reduced escort's effective sonar speed to 12kts both active and passive in accordance with (IAW) actual capability as I outlined earlier. Previously it had been 15kst for passive and 20kts for active which are just nuts. As I recall for PAIR in 1970 with rubber domes and a compartment full of signal processor cabinets it was 15kts for both; so 12kts for WWII IJN may actually be generous.
TROUT's location was in the East China Sea in OCT'44. Recd an intell rpt on a convoy. We steamed to intercept at 18kts and picked them up on radar from well ahead at 18nm. Seas were running about 12-15ft on a clear night with a fairly bright half moon astern of us. Normally, I wouldn't have engaged because water depth was 127-165ft, but I wanted to test. So I positioned to end around the stbd wing escort. It was a three column convoy of 3, 4 & 5 ships. The escort was six ships, all Type Bravo & Charlie coast defense corvettes except for an OTORI as tail end Charlie and a HOSHO Class CVE as last (5th) ship in the stbd column altho I didn't know that when I decided on my tactic. I picked the stbd side because that was the closest side to deeper water. Convoy speed was 8.5kts. We were getting an ESM green bearing line from what turned out to be HOSHO indicating she had radar altho she was the only one.
I went to radar depth w/ the closest escort 8nm away and went to PD with her about 6nm distant. I stayed at PD thereafter with the least scope showing possible, but the scope up almost continuously. When I lost radar contact the stbd wing corvette was 2000yd from the track of the stbd column on the same course as the convoy. Plan was to open that track to 4000yds and then end around that escort outside her detection range then coming in astern of her to pick off the last ships in that column. But as you know, no plan survives the first contact w/ the enemy. As I'm moving out from the convoy track, the stbd wing escort alters course and starts out toward us distant about 6kyds. I'm thinking, "Here we go again w/ these goofy detections." She was on our stbd beam target angle 20 degrees to port. I was doing 2kts and put the rudder over hard right to point her. She started swinging to her port and I was figuring we'd been had for sure. But she kept swinging until we were on her stbd beam. Her bearing rate was climbing fast so I got a quick speed check on her and she was doing 13.5kts. Deaf as a post. She CPA(Closest Pt of Approach)'d us at 2650yds and cruised on out to the head of the convoy.
By then I was perpendicular to the stbd column track, bow on at 3100 yds off the stbd beam of the third ship, a medium sized freighter, with a small tanker in station 4. We were well into the wing escort's baffles so increased speed to close the firing point. I let both merchies go by and fired five fish at the CVE from about 2600yds. Two were duds, peculiar in late '44, but the other three hit and she blew up.
At this point the tail end OTORI detected us at 2650yds and started signalling "Contact detected" on flashing light. I actually started in the navy as an enlisted signalman 3/c
. She was fine on our port beam and we still had a 2/3 bell on. She was bow on to us and appeared to be almost DIW. Not a detection I'd quibble with. We turned away w/ hard right rudder and put a Cutie into her which didn't sink her but allowed us to get away clean.
So that's the first run with these numbers in sim.cfg. I saved this at the pt where we were in first radar contact w/ this convoy so I'm going to keep trying various tactics and reporting the results.