Disclaimer— I am a complete noob with the ardusub and ROV. In fact, I am a mechanical engineer so when it come to programming and electronics gizmo you’ll need to use small word and basic descriptions.
I took my heavy configuration for the maiden splash today and have most things set, configured and calibrated except in the Depth and Stabilize modes the vehicle has a steady yaw to the starboard while the compass holds steady. If I correct the heading with control I put, the compass swings with the vehicle. The compass (and vehicle) is steady if sitting in manual mode.
Example: if the vehicle is pointed north and depth (or stabilize) mode is engaged, the vehicle will start to yaw right at about 1 rpm. Even as the vehicle turns the compass still pointing north. If the vehicle yaws 90 degrees and I correct with control input back to the north heading, the compass turns too and with the vehicle back to a north heading the compass will now show east.
I have done the compass calibration, controller calibration, accelerometer calibration and am now out of ideas.