Definitely "NO" on the 3D TDC. While it is cool, it only works in un-modded Stock. You would a lot of TMO, RSRDC & especially OTC. Your sonar situation sounds "backwards", compared to 'normal' sound, where you can hear a ship, but the sonarman can't, and that is due to a ship's engine sound being too low to hear, either because of a configuration or speed setting of the ship...
What you might be dealing with a cross-contamination. Anytime you make changes to mods in the game, you should delete the SH4 save folder in My Documents, so that the game pulls the proper new information of your mods back into the Save folder. I would suggest removing your mods, then deleting "C:\Users \UserName \Documents \SH4", then re-activate your mods. As Fifi suggested, using
Ralles RealModPack is the best / easiest way to do TMO / RSRDC / OTC, and have it all adjusted for good game-play. While he has been keelhauled, there are enough folks around here that can help you through set-up, or there are a couple of posts giving Bleiente's web site...
