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Old 06 April 2009, 11:46   #21
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For what it's worth, here's a pic of my console. The compass has no more than 5 deg deviation and doesn't seem to change when the radio transmits. Since the pic was taken there's a Garmin 550 on it's bracket to the right, where the black label is. Still no discernable deviation from the compass.

In short, put the radio where you'd like it.

Oh! Yes. My compass does work. I check it by driving down transits and also by comparing it with the true course given on GPS. It's a very deadbeat compass (i.e. it doesn't swing around a lot and is slow to react) made for powerboats.
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Old 06 April 2009, 12:56   #22
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Can't you buy shielded compasses? Or have I dreamt that?
Shielded compass? How would it sense the Earth's magnetic field?

Shielded VHF, perhaps (though I haven't heard of that, either.) IMO, the speaker is the worst culprit (or more precisely, the magnet in the speaker), though if the antenna is adjacent to the compass, I could see that having an effect.

jky
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Old 06 April 2009, 16:48   #23
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how about an electronic fluxgate compass, though i suppose a lot depends on how accurate you want to be as was said earlier on in the thread , for most small fast boats unless very calm are unlikely to keep within5 to 10 deg anyhow , for every one degree out it will put you 1 mile off course over a distance of 60 miles, ,,regarding paper charts i have one cut down to the size of the likely area i operate in and keep it in the flare box for emergencys ,encapsulated and i have drawn and marked all the likely way points ie lighthouse ,bouys,church spires,with the courses marked on the line so that i can go or get back without working them out at sea ,chart looks a bit of a spiders web but it works for me .
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Old 07 April 2009, 12:14   #24
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Hi JSP,

As most have said you will find all radio makers will issue a "compass safe distance" in the hand book, normally this is about 1m.

Looking at your pix, if it were me I would def move the mic looks a tad close, just a thought.

The question to ask do you notice if your compass moves when you transmit?
This is always a good indication that its too close. Also as you will know there is a magnet in the mic and in the speaker of the radio both can and will have some level of effect on the compass.

When I am doing an install I always check for compass deviation in the indicated install location.

Oh bye the way do you drive a blue Vectra and where you in a garage in the new forest today? if not you have a double!! :0))

Hope that might help a bit.
If I can be any further help give me a bell

Cheers

Jon
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Old 09 April 2009, 11:22   #25
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Thanks for all the help everyone. All taken on board. I think I am going to move the radio and ditch the compass. Instead I'll get one of those hand held's as back up in case the GPS is talking sh!t.

Jon, wasn't me. I live a long way from there. Cheers for the help and good advice
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Old 09 April 2009, 12:01   #26
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. Instead I'll get one of those hand held's as back up in case the GPS is talking sh!t.
regards the handheld compass ,from what i hear over the next few months sun spot explosions effecting gps signals will be high , you may need it more than you think ,lol
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Old 09 April 2009, 12:30   #27
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regards the handheld compass ,from what i hear over the next few months sun spot explosions effecting gps signals will be high , you may need it more than you think ,lol

Sods law

Did anyone see a repeat of QI on TV the other night where they where saying magnetic North was going to swap with Magnetic south
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Old 10 April 2009, 04:01   #28
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Sods law

Did anyone see a repeat of QI on TV the other night where they where saying magnetic North was going to swap with Magnetic south
i THINK this country has been going upsidedown for a number of years, but nothing to do with the magnetic pole , lol regards mart
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