Compasses in Pajeros

Submitted: Wednesday, Jun 30, 2010 at 09:34
ThreadID: 79747 Views:4127 Replies:6 FollowUps:8
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I have a 2007 NP Pajero and have tried several dash-mounted compasses and found them wildly inaccurate...due to electronic interference no doubt. Has anyone heard of a compass that will work in modern vehicles. I don't want more elecrical devices, just a plain indication of north & south. Thanks
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Reply By: Maîneÿ . . .- Wednesday, Jun 30, 2010 at 09:54

Wednesday, Jun 30, 2010 at 09:54
Probably to the metal in the vehicle if it's a magnetic compas :-)

I know that's what stops mine working correctly, have to walk away from the vehicle to get correct due north etc.

Maîneÿ . . .
AnswerID: 422563

Reply By: Member - Christopher P (NSW) - Wednesday, Jun 30, 2010 at 10:15

Wednesday, Jun 30, 2010 at 10:15
in car compass search in bing.

just did a quick web search and found a few suppliers.

Hope this helps
AnswerID: 422568

Reply By: Pete Jackman (SA) - Wednesday, Jun 30, 2010 at 11:00

Wednesday, Jun 30, 2010 at 11:00
Hi Vagrant,

Your car is a big steel box - no magnetic compass (even a fluxgate compass) will work even close to accurately without a whole heap of correcting magnets around the compass. The electrical currents are only a small part of the problem unless you put it on top of a main power cable. Nearby speakers are also a big issue because of their magnets.

A lot of work goes into this in ships. In a ship's magnetic compass binnacle the iron spheres either side, the Flinders bar (at the back where you can't see it in the picture below) and an array of magnets inside the case correct the compass card from the influence of the metal of the hull, machinery and super structure.


Even after all this there will still be a deviation card on the bridge to correct the compass reading depending on which direction the ship is pointing relative to magnetic north:


That is somewhat idealised as the curve is not normally that neat but the 6º deviation is not unusual for a corrected compass. And that 6º off track means evey kilometre you travel you will be about another 105 metres off your intended track.

See here for more info than you probably want:
Explanation of deviation

This is why most large ships these days use gyro compasses.

If you want an accurate steering compass a GPSS with the compass screen displayed is your best bet while moving. Explorer does a good one:


If you want a direction while stopped, grab your hand held compass and walk 5 to 10 meters away from your car.

Cheers

Pete
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Follow Up By: Pete Jackman (SA) - Wednesday, Jun 30, 2010 at 11:06

Wednesday, Jun 30, 2010 at 11:06
Sorry:

"If you want an accurate steering compass a GPSS with the compass screen displayed is your best bet while moving. Explorer does a good one: "

Should read:

"If you want an accurate steering compass a GPS with the compass screen displayed is your best bet while moving. Oziexplorer does a good one: "
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Follow Up By: Member - Trouper (NSW) - Wednesday, Jun 30, 2010 at 15:01

Wednesday, Jun 30, 2010 at 15:01
Peter,
Just loved your reply, am a bit into this sort of stuff having navigated all over the bush using a shooting compass, map and protractor.

Regards....................Jeff.. PS the compass is beautiful.
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Follow Up By: Pete Jackman (SA) - Wednesday, Jun 30, 2010 at 15:19

Wednesday, Jun 30, 2010 at 15:19
Thats how I learnt my bush navigation except with prismatic compass and a roamer rather than a protractor.

My first ship had a binnacle not too unlike the one pictured. The HMAS Supply. She also had one almost the same at the emergency steering position

My last ship had one that was more like this:



Still fully corrected though with little flat magnets glued around it on the helmsmen console. It worked OK and got us from the Solomons to Vanuatu when the gyro compass died.

Cheers

Pete
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Follow Up By: Vagrant - Thursday, Jul 01, 2010 at 13:00

Thursday, Jul 01, 2010 at 13:00
I appreciate your research efforts and will try to work out how to fit a ship's compass in the Pajero....perhaps I'd be better off putting wheels on a boat.
Thanks
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Follow Up By: Pete Jackman (SA) - Thursday, Jul 01, 2010 at 13:22

Thursday, Jul 01, 2010 at 13:22
Not research, I used to be a ships navigator - apart from te pictures this was all from the memory banks.

The short answer is that you need something other than a magentic compass for a vehicle. A GPSr displaying a compass rose (which most can) would be the most accurate while you are moving.

Cheers

Pete
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Reply By: vk1dx - Wednesday, Jun 30, 2010 at 16:03

Wednesday, Jun 30, 2010 at 16:03
When mobile and for a while after stopping the GPS is quite accurate for the direction out the front. You can works the others out from it. Don't know how long it retains such accuracy. I have never had to use it. Ours is one of the VMS in dash units.

What about the GPS?

Best of luck with the in-car search. All that metal and electronics is hard to get around.

Phil
AnswerID: 422595

Follow Up By: Vagrant - Saturday, Jul 03, 2010 at 16:23

Saturday, Jul 03, 2010 at 16:23
Looks like I'd better get a GPS....I'm still getting over th'lectric wireless. Thanks all xx
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Reply By: patsproule - Wednesday, Jun 30, 2010 at 18:55

Wednesday, Jun 30, 2010 at 18:55
Go to a 4wd wreckers and grab one of the factory fitted ones out of a higher spec Paj. They actually work fairly well.

Pat
AnswerID: 422619

Follow Up By: Vagrant - Thursday, Jul 01, 2010 at 12:56

Thursday, Jul 01, 2010 at 12:56
Thanks Pat. I'll give that a try.
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Follow Up By: Mike DiD - Sunday, Jul 04, 2010 at 22:31

Sunday, Jul 04, 2010 at 22:31
I agree.

They place the sensor at the top centre of the windscreen or rear window.
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Reply By: mynance - Friday, Jul 02, 2010 at 20:51

Friday, Jul 02, 2010 at 20:51
The NT Pajero has instructions to recalibrate the compass, in the owners manual, have you tried that in the NP

Myles
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