Problems with chartplotter accuracy - SailNet Community
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post #1 of 13 Old 04-01-2012 Thread Starter
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Problems with chartplotter accuracy

I recently installed a new Garnim (GPSMap 3000) and I suspect that it is not accurate. When compared with my estimated location on paper charts, and through visual navigation techniques, it seems that the chartplotter is showing my location as incorrect.

As you can see from this screen shot, the chartplotter is showing me off Decatur Island in the San Juans:



But this a photo of my actual location:



Could there be a problem with the calibration of my unit? Or could it just have something to do with today's date?
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post #2 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

I don't think it's the GPS, I think you need to make some changes to your Medical Marijuana prescription.
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post #3 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

Hmmmmm! What is today's date?

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post #4 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

OK, you need to take a visual. Make sure you have a clear view of the horizon. Now pick up the Pusser's bottle and sight the horizon through the bottle.

Can you clearly see the horizon through the bottle or is there brown liquid in the way?

If you can see the horizon clearly (no brown liquid) you've solved the mystery.

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post #5 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

And they say there's no wind on the moon!

"Next best thing to not having a boat? The knowledge from having one!" Denise, Bristol PA, On Tidal Delaware River, Anchor Yacht Club.
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post #6 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

I think the GPS only provides an accurate fix for terrestrial locations ;-)

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post #7 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

Ehh....close enough.

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post #8 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

That big blue/white marble is really going to screw up your celestial fix - I'd just ignore it
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post #9 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

Once the Tide comes back in you'll be fine!
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post #10 of 13 Old 04-01-2012
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Re: Problems with chartplotter accuracy

did you do a dead reckoning to verify your present location, you could be in a deferential pile with the same stuff

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