I have uploaded to FileFront a mission that when installed, will give you a chance to compare range finding accuracy between the stock game and my Ship_Centered_Accuracy_Fix 1.0. The revised version can be found at the thread
https://www.subsim.com/radioroom/showthread.php?t=126016.
The test mission has three stationary ships, at varing distances from your submerged stationary sub. Follow the readme for setting up the options and give it a try. I think you will find manually finding range has increased in accuracy when using the modification. The mission test download is called "Range Test S_C_A_F 1.0". The link to the downloads are:
http://hosted.filefront.com/capnscurvy/