Try running without RFB, if you get decoys with a new career in the stock game, then RFB has something in it that disables decoys.

Just an interesting side note about the decoy systems.

The loss of German U-Boats early in the war caused Hitler to convene a meeting with his commanders in Sept. 1942. Hitler himself had the idea of putting oil and floating debris into a torpedo that would explode and float its contents to the surface, indicating a sinking. Although at first, the idea didn't get off the ground, other ideas like the Hydrogen Bubble Canister did. I'm assuming the Germans had the "Bold" system by early 1943.

Likewise the Americans had a meeting in Dec. 1943 to do the same (no doubt referencing what the Germans had been up to). I would guess a similar decoy system was put into practice, probably early 1944. It's hard to get direct information regarding just when systems like these were introduced.

The stock game may not reference the decoys as accurately as they should when they were put into practice......thus the modded differences with the dates. Some mods having the availability of the decoys more accurately portrayed.

actually, that's not true. I have sat right on the edge of a task force after having lured the destroyer screen away and dived underneath them, taken out battleships, and so long as I am just far enough away that they can't see my periscope, and I'm running 1/3 speed, nobody notices me. I have done this repeatedly, and the big capital ships do nothing but run into my torpedoes.

the key is just to lure the destroyer screens away by being VERY noisy on the surface during your long distance approach. they will bum rush you, and just before they reach visual detection range, you crash dive below the thermocline, shut your power to 1/3, and cruise right underneath them using silent running. do that for about 400 yards, then up to periscope depth, and they are running in circles behind you, while you line up your shots on the capital ships.

really, this works every time for me.