Compass deviation from chart plotter?

[bobdoughty]

Hi. Has anyone experienced steering compass deviation caused by siting a chart plotter (Garmin 450) about a foot away from the compass? I can hook it up and wave it around near the compass to see if it moves but there may be a more scientiific approach - or no need to worry given the low current consumption. Thanks as always

 

[ebbtide]

Yes! Solution: get a professional compass adjuster to sort it.

 

[boatmike]

I don't think there is an easy answer. I was worried about this not knowing, and have just tried it with a SH500 plotter (12" screen) and it didn't make any difference at all about the same distance away. I think it's more likely that any ferrous material in the construction of it would have an effect ratherthan any magnetic field it generates but go for the non scientific approach and try it before you permanently mount it.

 

[wotayottie]

Connecting it up and waving it around whilst monitoring the compass is a perfectly good way of seeing if there is a problem. make sure all the plotter functions are on ie max back light etc. and go closer to the compass than you would site the plotter.

If I remember rightly, the strength of the magnetic field is proportional to the current and to the cube of the distance.

Do you really use the compass?

 

[charles_reed]

I think you'll find about 1m away and you'd have nothing about which to have concern.

TFT screens produce nothing in the way of stray magnetics compared to CRT.