Earlier last year during our circumnavigation of Australia our autopilot would intermittently flash up “no data” and spear off at 90 degrees to our desired course. After several satcoms with Jim in Newcastle we determined it was VHF interference emanating from the AIS. Here is a pic of me becoming overwhelmed with wiring in the console trying to icilate the issue. We finally fixed it in WA with a heavy duty earth to the AIS and a GME band splitter to the VHF mast top aerial.