@ TDW
I am just about to test the radar again looking at a large tanker at 90 deg in foggy weather - just to find the max range of the radar.
So far both the radar and the radar warning as a range of 8km max.
Could it be that the watch crew is in control of these sensors (surfaced)?
I am sure I have seen a setting in your options.py where the watch crew has a limit set at 8km

(I can't find this setting in the options editor - perhaps it is edited in file only

)
Edit: cant find it - it must have been the setting for max distance before TC drops
Could this be restricting the radar too