Compass moving with New Graph Install

[S * K]

I just bought a new hummingbird and I am trying to install it on my boat and its within about 1ft or less of my compass. As soon as I get within about 1 1/2 feet the compass moves. How do I prevent this.. I would like the compass to work just incase the electronics take a sh** while out in the water. 

 

Whats the trick?

[Don Supon]

Relocate the compass, especially since you have it for back-up duty. HummimBird installation instructions warn of this problem, so I don't think there is a way to defeat the problem and mount them that close. Perhaps a ram mount for the FF (or compass) will give you the needed seperation.

[S * K]

Thanks, I will look into as compass in sunk into dash and I don't want the big whole showing. I guess its one or the other..

[Thun]

There are some things you can do to but it takes a bit of effort to accomplish. First you can remove most of your N-S, E-W compass error and then make a deviation table to compensate for your boats magnetic influence on your compass. Add an RPM chart and you could navigate safely using only time, speed and distance calculations. It's called dead reckoning.