E-120 Chart Plotter COG vector error

[Sea Path 44]

I have a Raymarine E-120 and an ST7001 Autohelm. I did the re-cal on the Autohelm (spinning around a couple of times and got down to a deviation of 2 degrees). All was good for a few days. Yesterday, I was running and suddenly, my COG vector line (red line) on the chart plotter started to aim anywhere from 5 to 90 degrees different from my true course (different than my running direction). The ST7001 Autohelm compass reading is on the button and the boat it tracking correctly on the chart plotter but the COG vector (and boat icon) is askew, again, with the degree of error constantly changing. Any suggestions on how to fix this?

 

[Four Suns]

COG vector? I don't have an E-120 but the vector on the RL80CRC chartplotter is from the heading sensor and not the GPS. The ST7001 compass reading also comes from the heading sensor so your symptoms seem strange to me. You sure your ST7001 reading you are looking at is the compass reading and not the setting? My reading underway on my ST7001 when the auto pilot is engaged is the setting and not the heading. When I disengange the ST7001, then the heading is displayed... Your description leads me to believe you are looking at the setting value and not the heading value...

If that's the case, you are experiencing a bad calibration or just a bad piece of crap fluxgate. The raymarine fluxgate is the WORST PIECE OF CRAP ever installed on a boat and will do this....

Have you been in any heavy seas or hit a big wave since your calibration? That will knock the RayCRAP fluxgate out of whack...

Get a KVH Autocomp fluxgate/heading sensor and your world will be in harmony. Tie the raymarine fluxgate to the bumper of your car and drag it around town.... better yet... send it to promocop and let him hook it up to his steller Sea Ray Navigators.

Another thing to check is to make sure your chartplotter and autopilot are both set to either "True" or "Magnetic" for the compass. They need to be set the same... Mine were not at one time for some reason and the things got all Kearney on me.