I have had this warning message occur twice in the last 12 months. On checking the diagnostics the deviation currently reads 177 degrees! When I initially calibrated, the deviation was 5 degrees. (Raymarine say anything in the range 5 to 10 is ok. Otherwise too much metal near the EVO compass)
Both times this warning started happening about half way between the end of the West channel and my Hobsons Bay mooring. I guess it could be some strange magnetic anomaly there but unlikely.
The Raymarine manual says I can software lock off the calibration process which continuously adjust for magnetic changes. I suspect this automatic and ongoing calibration process gets confused when the bow of my cat swings from side to side coming up the bay against very rough choppy seas.
I know when I restart the calibration routine on a calm day and motor around in 2 circles the deviation will be reset to around 5 degrees again. And I suspect that if I lock the automatic calibration process off I wont see this warning happen again.
And just to confuse things. Raymarine only ever use the term deviation... Even when they refer to the automatic calibration process correction for changes in the magnetic field at different locations in the world... Which of course is magnetic variation!
And how can the diagnostics report deviation of 5 degrees. Just one number! Surely it's not 5 degrees deviation for all headings.
HAS ANYONE ELSE BEEN THROUGH THIS???
Raymarine call the calibration process compass linearization. What is really happening???
The installation manual procedure requires the boat to be motored around in a circle at a speed greater than 3 knots until the software says calibration is complete. The manual also says this calibration process continues in the background after the initial calibration. (to adjust for changes in magnetic field while sailing to other locations)
I am pretty certain the problem occurs because the system gets confused when this automatic background calibration happens when I am sailing in very rough and choppy seas with the bow swinging left and right as we make way at an angle to the swell.
The software permits locking of the compass calibration after initial calibration. I am going to lock it this time when I re-do the initial calibration.
I am just trying to find if anyone else has found this with their similar Raymarine set up so I can confirm my understanding is correct.
