Your sonar guy is one of your best men. Try to get his spot on bearings yourself and you'll realize how well trained he is. Keep your Luger beneath your pillow, Herr Kaleun.
The FAT/LUT are fun in combination with hydro data only. Remember to check the settings twice - or learn it the hard way.
Good luck in '43 Herr Kaleun, keep an eye at the flyboys while snorkeling. They tend to be nasty.