Compass conundrum

[Scallywag-l36]

So.... Autopilot shows heading exactly 180deg opposite to my actual heading, boat cursor on chartplotter shows boat pointing opposite way to actual, ie going backwards. COG is correct on chartplotter. Powering off and on a few times, but no change. Any suggestions...? (sorry not at all hunter boat specific!). BTW I have raymarine gear inc fluxgate compass throughout, approx 6 years old

 

[caguy]

In your Raymarine manual there is a section on Initial Sea Trial and Calibrating the compass.

 

[Don12364]

Is this a new thing resulting from a new plotter installation or has it always been thus? Have you altered any of the connections or replaced any components? Are you moored alongside or under way when you see this?
Sorry for so many questions but a little more information may help diagnosis.

BTW GPS cannot know your boat heading unless you are moving - so when in reverse the arrow points to your stern.

 

[Dave602]

Good questions by Donalex. How long has it been going on? What model Autopilot? Anything near the compass? I just finished an installation of a Smartpilot x-5 on my boat and found the chart plotter affecting my fixed compass by 7degrees. So one of them needs relocating. Raymarine items usually have set up and cal instructions. Check your model on line and you can down load the manuals. I have all my manuals down loaded to my laptop so I can have them handy.

 

[robertsapp]

Which way does your fluxgate compass point? If you've done a calibration recently, or maybe if the autopilot just somehow reset itself, it assumes the default position for the dome shaped housing of the fluxgate compass will be facing forward. If you can see yours, see if it's facing aft. If it is, there is an offset you have to enter in the setup. How do I know? Because I recently recalibrated my ST4000+, and then everything read 90 degrees off. My compass faces to port (mounted on starboard sidewall of bilge) so I had to manually enter a 90 degree offset in the setup screen. Worth checking into.

 

[Scallywag-l36]

Thank you all for your replies so far. I must admit to having let down the male population of the world in that I HAVE NOW READ THE MANUAL!!! The original problem manifested itself when underway, had been fine the last time I went out, and I had fitted nothing new or put anything new in my locker near the fluxgate. Hmmm. Anyway, it seems the ST4000 somehow lost it's settings, all I had to do is get an accurate heading using my inboard spare handheld GPS then go onto 'setup' of the ST4000 and adjust the heading settings to match the handheld settings. Problem solved! I switched everything off and back on some hours later and it still reads correctly. C80 Chart plotter on the cockpit binnacle now somehow keeps defaulting to show heading ribbon display across the top of the screen instead of my usual data boxes, but a few menu option selections puts them back again. Must be gremlins in the system caused by unseasonably warm weather here in UK at the moment!