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#1
posted to rec.boats.cruising
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Compass reading wrong?
"Steve Lusardi" wrote in
: It's wonderful, but how do you use it? Steve "Larry" wrote in message ... http://www.geomag.us/models/WDMAM/WDMAM_NGDC_V1.1.pdf No WONDER the damned compass won't compensate! -- "iPad is to computing what Etch-A-Sketch is to art!" Larry I'm not sure. It's calibrated in nanoteslas + and - so there seems to be pushing and pulling the card at various magnetic levels that keep shifting, it seems. Zooming in on the Charleston-Savannah area, there are several strong magnetic anomalies of BOTH directions. This chart may also cause the compass to spin in both directions at times....a very worrying condition: http://www.kitco.com/images/live/gold.gif -- "iPad is to computing what Etch-A-Sketch is to art!" Larry |
#2
posted to rec.boats.cruising
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Compass reading wrong?
Larry,
I can't see that this is overly significant. Please note that the color swing is from +200 NT to -200 NT..(1 NT = 1T x 10 -9) The Earth's magnetic field typically ranges between 3 and 5 T x 10 -5, at least according to Wikipedia. .I use a magnetic compass as a backup only. The cost of satellite compasses today is very affordable. and some also have dead reckoning and a fluxgate built in incase of signal loss. This beats the hell out of the donut you create when the autopilot is slewed to a fluxgate and you sail over a sunken power cable. This can be very exciting. Steve "Larry" wrote in message ... "Steve Lusardi" wrote in : It's wonderful, but how do you use it? Steve "Larry" wrote in message ... http://www.geomag.us/models/WDMAM/WDMAM_NGDC_V1.1.pdf No WONDER the damned compass won't compensate! -- "iPad is to computing what Etch-A-Sketch is to art!" Larry I'm not sure. It's calibrated in nanoteslas + and - so there seems to be pushing and pulling the card at various magnetic levels that keep shifting, it seems. Zooming in on the Charleston-Savannah area, there are several strong magnetic anomalies of BOTH directions. This chart may also cause the compass to spin in both directions at times....a very worrying condition: http://www.kitco.com/images/live/gold.gif -- "iPad is to computing what Etch-A-Sketch is to art!" Larry |
#3
posted to rec.boats.cruising
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Compass reading wrong?
"Steve Lusardi" wrote in
: This beats the hell out of the donut you create when the autopilot is slewed to a fluxgate and you sail over a sunken power cable. This can be very exciting. .....especially with a bulb on the bottom..... -- "iPad is to computing what Etch-A-Sketch is to art!" Larry |
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