Vehicle-mounted mag compass
 

Anyone have a reliable experience with these? Was it easy to set up? Is it genuinely accurate in all directions?
IME, it's a nice idea but I've found some vehicle/model combinations work better than others. And I've never had either.

CS
(p.249)

IMHO, the in-vehicle compasse is good enough for general guidance only as setting it up correctly is a real pain. It is affected by a variety of factors leading to magnetic field disturbance, so even switchng the lights on may deflect the pointer a few degrees.

The fluxgate compass has a slight advantage over the magnetic type insofar as the sensor can be positioned away from the display in an interefernce-free spot.
It responds instantaneously, which makes the fluxgate a bit better for vehicle use. The effect of large metal objects on it is no different from any other compass, but the effective pickup area of fluxgates is somewhat larger than for needle compasses, hence you can get some averaging that way. Finally, the compensation for nearby metal objects in the presence of limited tilt is easier for fluxgates than for mechanical compasses. On the other hand, the magnetic compass is less affected by tilt.

Whatever the limitations may be, the compass is a usefull aide to the GPS as it works always, regardless of the of vehicle speed.

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Roman (UK)
www.overlandcruiser.info

Hi Chris

I had a Silva boat compass on the dash of my Pajero, in front of the driver. I found it very useful in the desert to keep us on course, and even more useful in towns with no signs to give me a clue which way to turn!

The deflection was constant, and fairly irrelevant as you can only drive to within a few degrees, and take a fix when possible.

Happy Trails

Bruce

I have Silva vehicle compasses in my LRs, and find them very useful.

GPS sits out of the way, and navigator gives driver an approximate direction to keep to (NE, SW etc.). Accuracy of compass is better than this and more easily glanced at than the normally busy screens of a GPS.

The point about using them in towns is very valid...

Sam.

I've used a Suunto Pilot marine compass for a few years dash mounted in a Land Rover 90 and it is a good combo, the mount system works well for any angle you want and it has a 12v backlight fitted, to connect up to the vehicle, It's easy to set up with good deviation adjustment, its not too big, it doesn't take over the whole dashboard. I also use it as a spirit level, to get the roof tent flat. It was fine for a western trans ive just done, no problems with Mali corrogations. My etrex Summit is mounted near to it on the dash, and looking between them whilst on the move,the compass is only a couple of degrees out on any bearing - which was handy, as the etrex packed up back in Morocco (no power up) and as the guys say, it's handy when your finding you way around downtown Nouakchott in a sand storm !

Roman, which fluxgate compass do you use / recommend?

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A.B.

OasisPhoto.com – Images from the Magical Sahara.
ShortWheelbase.com – Jeep preparations.
Coordinates Converter – Lat/Long <-> UTM Conversion Tool.

Hello A.B.

I used to have a NASA Clipper (sold with the previous vehicle). Expensive but very good.Read about it here:

http://marinestore.co.uk/Merchant2/m...gory_Code=nasa

or here:

http://www.mailspeedmarine.com/detai...QLID=MD-284210

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Roman (UK)
www.overlandcruiser.info

Thank for the link and Yep, £189.99 is very expensive..... http://www.horizonsunlimited.com/ubb/frown.gif

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A.B.

OasisPhoto.com – Images from the Magical Sahara.
ShortWheelbase.com – Jeep preparations.
Coordinates Converter – Lat/Long <-> UTM Conversion Tool.

Hi Chris
I don't know if aircraft compasses are any different to marine ones, but they have small adjustable compensating magnets at right angles to each other to make up for the distortion to the earth's magnetic field caused by the various lumps of iron in your vehicle. Fields caused by your electrics present their own problems. You can get second-hand air compasses without a certificate of serviceability cheaply, I think mine was about £30 about ten years ago, they said it was off a Phantom, well, they would- keep the punters happy. Try Light Aero Spares in Shebbear, or RD Aviation, you can probably find them on the internet no bother. Also, try Yorkshire Light Aircraft, Leeds-Bradford Airport, Yeadon, Yorkshire.
John

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Johnefyn

I believe that the marine ones are not much different than the air ones.