Hold up. Let's just nip this in the bud before it goes any further.
I took a look at the sensors.dat file that comes with RSRD. It seems to be concerned with German U-Boat equipment. Here is a screenshot.
As you can see, this has no relation to US fleetboats. I'm not quite sure what this is doing in RSRD but I am sure Lurker has a good reason for it being there. This file does not affect fleetboats.
The files that affect fleetboat sensors are all called 'Sensors_sub_US'.
RSRD makes no changes to the 'Sensors_sub_US' files.
Looking at the files included in RSRD leads me to believe that RSRD is not responsible for any shortcomings in the visual detection model in RFB.