Originally Posted by Dockhead
OK, thanks, but our autopilot works perfectly. My real puzzle is how could the autopilot be getting good heading data when the radar/plotter does not. It doesn't make any sense to me. They're all on one network as far as I understand. Or?
You are jumping to conclusions when you think the autopilot is getting good heading data (while the radar
(apparently) does not). What is certain, the radar shows erratic info while the autopilot seems to be doing just fine.
Possible reasons, non-exclusive list:
- autopilot does data processing fine, radar does not (software problems or hardware
- one of the above using compass
data while the other using data from another source,
- differences in set-up mask erratic data (e.g. by the use of averaging filter),
Depending on your autopilot unit, you may be able to tune the averaging to the allowed minimum and check the readout in standby. Another thing one can do is unplug the compass
from the unit and plug
it in at another point (network bus or the other instrument).
Again, make sure the cabling is fine (shorten the cables
in freshly stripped cores), make sure the compass is fine (by doing the tests as per Raymarine instruction) and by observing the compass readout on compass (or autopilot) instrument with tuned down averaging.
Go piece by piece, starting with the most obvious: connections, cables
, the sensor, and so on. One element at a time, and you will find the bug.
PS You do not have to take the boat out for tests - just dismount the compass sensor and turn it by hand).