plotter spinning image



I am experiencing a strange 3D problem. The other day, the electronics were left powered on at the dock and the batteries went low enough that only the outboards would run. No electronics would power up (VHF x 2, GP-33, RD-33, NavNet 3D, FA-50). Charged the boat at the dock overnight. Electrical power has been restored.

Now, when underway, the plotter displays my vessel icon as continually rotating in 360 degrees. My course is accurately displayed, but the boat icon is constantly rotating. If I change the display from North Up to Course Up, my chart graphics continually rotate around the vessel while underway or at the dock.

The radar behaves in a similar manner. If I choose North Up, AIS targets rotate around my vessel, but the radar image is appropriate to my vessel orientation. If I choose Course Up, then the radar image rotates around and around.

And if I overlay the radar on the chart, forget it. Either one is stationary and the other is moving, or vice-versa, and the AIS is either moving or stationary.

If it wasn't such a pain in the neck, it would be funny.
It sounds like something has happened with the heading sensor in the system.
Try disconnecting the compass and see if the problem stops. You won't be able to do radar overlay but you will isolate the problem.