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Discussion Starter #1
I have a nexus autopilot. The PO had a messy Nexus/Raymarine set up.

It seems a new fault has developed which is strange. Underway, the nexus systems (reading from the compass I assume) read about 0-5 degrees off the Raymarine GPS fed reading. Normal I assume, compasses never read the same :)

The issue is, the moment I engage the autopilot on a bearing, the nexus-shown bearing jumps 20 degrees starboard and the autopilot lurches to the left.

Currently, the autopilot is useless......

Any ideas? Nexus support was no real help.
 

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Since the fault developed, have you carried out a compass set-up for the autopilot?

I had a similar problem with a Raymarine autopilot, but that was one wire that broke off the fluxgate compass.

Can you feed the autopilot from the GPS on a track mode? This may show whether it is the autopilot compass or other fault, by eliminating the autopilot compass.
 

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Crealock 37
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It kind of sounds as if the compass for the Nexus is being affected when the auto pilot is engaged. Has anything installation wise been changed? Anything installed near the compass that wasn't there before?

On Elnora if we use our little one-cup hot water maker (110v off the inverter) to do coffee, etc the Raymarine AP compass goes it bit wonky showing a big bearing change of about 60 degrees followed by a honking turn to "get back on course". The AP compass is under the chart table (port side), coffee maker in gallery (starboard side) and the inverter is well forward under the settee.
 

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I have a nexus autopilot. The PO had a messy Nexus/Raymarine set up.

It seems a new fault has developed which is strange. Underway, the nexus systems (reading from the compass I assume) read about 0-5 degrees off the Raymarine GPS fed reading. Normal I assume, compasses never read the same :)

The issue is, the moment I engage the autopilot on a bearing, the nexus-shown bearing jumps 20 degrees starboard and the autopilot lurches to the left.

Currently, the autopilot is useless......

Any ideas? Nexus support was no real help.
Not familiar with your gear or boat, so this is a shot in the dark.

Is the fluxgate compass for your autopilot located a good distance from your steering wheel? If it's too close, the autopilot's motor may be creating magnetic interference.

Some higher-end autopilots have an clutch that automatically engages when you hit the "Auto" button. If that is an electromagnetic relay or solenoid, it could create huge interference for the fluxgate compass if it's located too close.
 

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Discussion Starter #5
Thanks for the ideas.

The compass isn't especially near anything. Its a new problem, it was working a few days ago.

The next part in the saga however is that now the Nexus displays are not showia bearing of any kind. They are just blank.
 

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I could not figure how to get a response to you on the other subject you have a lot of parts for a 28 ODay if you happen to hsve any of them left please let me know
My name is Billy and have a 28 oday
I can be reached at ph 910-206-2468 or email [email protected]
I know it was a old post but worth the effort
Thank you
Billy
 

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Discussion Starter #7
Sorry to resurrect this old thread.

I got a new nexus HPC compass, and things seemed to go well on our trip south, thousands of miles. Now, we are heading home, and our sailing is almost all downwind.

It's an Autonav, the AP 1500 that uses an original Nexus display unit.

I am struggling to get it to function. I have tried to incrementally adjust the calibration settings, but no matter what I do, the autopilot will hunt back and forth ever increasing until we are turned so far off the wind, we get overpowered. The problem is exacerbated in following seas when swell will turn our rear around.

Our boat is a 1974 Tartan 41, which isn't great downwind, but still...

Does anyone have an original nexus and can recommend some starting calibration numbers and then a good adjustment method. I can't seem to get the four setting right ><
 
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