"donkey" u35732@uwe wrote in message news:74f9791e8c9a4@uwe...
I have a raymarine auto pilot where the compass either has 'no data' or
will
just simply show the wrong data. I understand the reason could be a
metalic
object near by. So I know where to look, how far from the compass should
there be no metalic objects? Does the compass only read in the direction
immediatly ahead or is it all around or does it just pick up north, hope
someone can help. Mark


"No data" is not going to be caused by a piece of metal, magnet or
conducting wire nearby. This sounds more like a bad connection somewhere,
either internally or on the connecting wires. If you have any magnetic
fields nearby the compass will work but the readings will be off and when
you do a calibration you should see a large deviation number, say 30
degrees. Totally wrong numbers also sound like a bad connection or
defective fluxgate compass. These sometimes corrode internally and the
wires break.

How far away the metal, magnet or wire should be depends on how strong the
magnetic field is so you can't generalize.

Thing to do is use a hand held compass to check your location. Hold the
compass a couple of feet above, or away, from the compass location and then
slowly bring it towards the compass location. If the needle starts swinging
you have a magnetic field in that area and probably should relocate the
compass.