Inverter on,GPS/autopilot compass swings off 10 degrees

[RickD]

I think I have pretty much been stating "DC" and the wires all along

Originally Posted by bill good

RickD,

If it were my problem I would relocate the inverter to have the shortest DC leads to it thus reducing any magnetic field caused by the DC current.The AC output is not going to effect the compass. The fact you have DC Hi current 1' from the compass would appear to be the problem.

Regards Bill Goodward

[H/V Vega]

I would be more than willing to bet that one of your AC cables runs somewhere very close to the auto pilots compass. When I first got this boat the @$#%^&@@** who had it before had put all of the electrical switches only inches under the main steering compass. Every time I turned something on or off the compass reading changed! That problem is now well and truly solved but learn from my headaches. Electrical cables create a magnetic field when current passes through them. The more current the stronger that field will be. So grab a torch and start rummaging for that cable

Best of luck and happy sailing

[H/V Vega]

sorry am getting old I guess

"Since there are DC power cables involved, I think you might find the heavy wiring used to feel the inverter is the culprit, rather than the inverter itself"

Start with that lot. Then move the stereo speakers from right beside the compass and perhaps even the ice maker. Just joking mate! Do check the main power cables and how close they run. It is usually possible, notice I did not say easy, to re run them further away from the fluxgate.

[donradcliffe]

I think we have found the smoking gun! The high DC current in the 12V cable to the inverter is the most likely cause of the compass deviation. Rerouting the cable or possibly twisting the negative and positive cables near the compass should help.