COG differs from heading, but radar overlay is correct.



I have a weird and a bit annoying issue on my MFD's. The COG predictor is about 10 degrees off compared to the heading.

I have configured the PG-1000 heading sensor by turning five large circles on the sea. The radar overlay is correct. But the heading predictor is wrong compared to the COG preditor. It can be from 0 to 15 degrees off.

When aiming the boat at a lighthouse or similar, I see that the COG predictor is the correct one. The boat icon on the MFD follows the heading predictor, so the boat is slightly skewed when driving foreward.

Is there a way to align the map and boat icon to the COG, ignoring the heading predictor? I know I can turn off the heading predictor and just enable the COG predictor, but the boat icon will still be skewed...

If I turn off the heading sensor, the plotters will use COG and the boat and the map will be correctly aligned, but then I lose radar overlay and ARPA.

This is a screenshot of my plotter today:
You can change what the boat icon uses to point itself under Menu, Ship & Track, Boat Icon Orientation. The choices are heading or COG. In your case, change it to COG and turn off your heading predictor to get what you asked for. Please keep in mind that COG is not valid until moving 3 knots or better, so the boat icon may be backwards or pointing in an incorrect direction all together if moving slower than that.

To fix the heading and COG not matching, it appears your heading compass needs a correction. The best way to tell if heading is accurate is to compare it to the ship's steering compass and adjust the fluxgate compass to match. If they match when sitting still and don't when moving or pointing in different directions, then there is some sort of magnetic interference pulling it off.
Thanks for the answer! I didn't see the boat icon orientation menu choice :)

Now the map and icon is correctly oriented. I will look more into the compass calibration later. For now the COG will do the trick :)
Are you set to True on one and Magnetic on another? That's a 12 degree difference, and could be your trouble.