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Old 24-11-2015, 02:36   #1
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GPS in Open CPN

Hi,

Trying to set up my GPS with OpenCPN. Just finding my way around this forum, not doing too well so far!
Have set up a BU353 GPS, and the ship track that is made from this GPS signal is in the wrong place on the open cpn chart! It is .56 of a nm west of where it should be on the CM93 chart. I've tested this with my ipad with an inbuilt GPS so I know something is wrong with my GPS-Opencpn system, as the ship track from the GPS is in the incorrect position.
Can anyone help please?
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Old 24-11-2015, 04:45   #2
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Re: GPS in Open CPN

What operating system ?
Witch version of OpenCPN
Position displayed by the GPS if dachboard plugin is enabled ?
CM93 maps -> witch date/release ?
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Old 24-11-2015, 12:06   #3
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Re: GPS in Open CPN

Operating system is Windows 7 and Windows 8 (I have OpenCPN on 2 laptops)
OpenCPN version is 4.0.0
Dashboard plugin is enabled. The current position is 16 46.664 S, 179 20.080 E
CM93 maps info:
Scale 1:20,000; Datum WGS84; Projection Mercator; Updated 2000-01-01
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Old 24-11-2015, 12:44   #4
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Re: GPS in Open CPN

See attached map. The triangle in center of the map is the position you gave displayed in Opencpn 4.1.1108 using CM93 July 2012 maps.

Does this seems to be the same position that the boat is displayed in yopur maps ??

If you right click the object query in the map on this position, there are warnings about GPS being more accurate than the map in this area.

Could the reason bee that your Ipad is using more updated maps ??
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Old 24-11-2015, 13:50   #5
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Re: GPS in Open CPN

Thank you, my charts are old and the choices are many. Please point me to where I can download the CM93 July 2012 maps?
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Old 24-11-2015, 14:41   #6
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Re: GPS in Open CPN

I has purchased mine some years ago to be used on a non SOLAS commercial vessel. Since the chart system was upgraded and now is using S63 charts, the CM93 charts from the old system is now used for opencpn.
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Old 24-11-2015, 14:58   #7
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Re: GPS in Open CPN

Thanks for your help. Not exactly sure what you mean totally, but appreciate your interest.
My charts I have realized are very old.
Can you or anyone else tell me where to go to download the latest vector charts (CM93). Is there a website to go to? I will be sailing in Fiji and need these charts first up.
Appreciate all help as I navigate (pun intended!) my way through this.
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Old 24-11-2015, 23:53   #8
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Re: GPS in Open CPN

Search the forum - you will find the answer to your question.
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Old 24-11-2015, 23:55   #9
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Re: GPS in Open CPN

JMK...
I don't think It's about chart editions. I get the same position in newer CM93. I haven't tried my self but heard the accuracy is bad in this part of the world.

Make a search in Google for CM93 edition 2 and you'll find a lot.

Håkan
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Old 27-11-2015, 01:10   #10
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Re: GPS in Open CPN

Quote:
Originally Posted by JMK200 View Post
I will be sailing in Fiji and need these charts first up.
All the charts for Fiji especially the northern reefs are based on very very old 18th century surveys. In fact the "latest" for Bligh Water were done by Capt Bligh. They are spectacular considering when and how they were done but not good for "chart plotter navigation", due to offsets and orientation discrepancies.

Even though electronic charts may say 2012 or even 2015 it does not mean the data is any more accurate for this area. They have never been properly updated from hydrographic surveys as no big ships ever go there.

It is worth preparing Google Earth KAP charts for the area to use with OpenCPN. Check with local cruisers for copies as I know someone has already done this.
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