[NorCalBoater]

I just saw the other post on the Simrad AP issues but mine seem a bit different.

On my 50' Kha Shing the PO had a full RayMarine Electronics package installed about 4 years ago. The system includes C120, open array 24 mile radar, GPS, Navionics Platinum, AIS and the ST8001 auto pilot. All of this is at both stations. From the invoices and all of the bells and whistles he did not go cheap.

The problem is that when I go from Standby to Auto on the AP I get a 3 second message that says "No Rudder Data." That flashes off and the AP takes over. But then the boat begins to yaw back and forth in increasingly larger arcs until I switch back to Standby.

While in Standby the heding may indicate the actual heading but rarely. And it never holds. It is always moving and changing even if I am holding a steady course.

I've looked at the manuals and gone through the setup and compass calibration but I know I am doing somthing wrong. I believe the system has a fluxgate compass but can it also get heading info from the GPS?

What am I missing?

Thanks,
Shawn