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Old 02-24-2012, 12:22 PM   #1
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C-Map Cartography Discrepancies

Just got off the phone with Jeppesen regarding cartography errors with my c-map max Canada West data card. Specifically, there is a problem with the rendering for CHS chart #3477 (southern Gulf Islands of BC). To keep it short, for this chart area, the land and water for the*chart show too far west by about 0.1 nm (about 200 yards). Nav markers and road overlays are correct but the water and land are wrong. For instance, my mooring buoy shows as being about 100 yards on land and some roads look like they are in the water. It is not a problem with my 3 GPS plotter*units. *Jeppesen customer service replicated this at their end and will pass it along to the technical department to "fix/update" for future releases. The rep said user feedback is the only way they can identify some of these anomolies.

So, this just reinforces not to trust your plotter charts as your main or only nav aid. I checked other nearby areas I am familiar with (Sidney/Victoria/Cowichan Bay/etc.) and they seem okay but for chart #3477 (Pender/Mayne/Saturna/etc.), at least, be careful because*200 yards could put you in a jackpot.*Doesn't make me feel quite so confident heading north to Sunshine Coast/Discovery Passage this year.

Sorry for the wordy post.

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Old 02-24-2012, 12:39 PM   #2
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RE: C-Map Cartography Discrepancies

That is valuable info. *Not the area I boat in, but should be useful to others. *The only area that I have found *consistently off on my C-Map charts is in the GICW from about the Albee Road bridge to Venice Inlet. *It consistently shows the channel about 75 yards East of the actual channel. *If the chart was followed there, you would be ashore.
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Old 02-24-2012, 12:48 PM   #3
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C-Map Cartography Discrepancies

Quote:
saturnaisland wrote:
Just got off the phone with Jeppesen regarding cartography errors with my c-map max Canada West data card.

*****
Must be a problem with that specific chart edition.* Our earlier* (1998) C-Map charts for our older plotter and the Max card we use in our Furuno NavNet are right on the money for that part of the Gulf Islands.* We go to Cabbage Cove on occasion and our boat's location on the buoy is dead on.

But the point about not totally trusting the electronic charts is a good one.* We run two dedicated plotters at the helm as well as have the paper charts out all the time.* So far we've not found an obvious discrepancy on either of our C-Map plotters but you never know.

I'll have to check the cartography for that part of the world on the new Standard Horizon plotter we bought last year for our smaller boat.* It's C-Map, too, which is the cartography we prefer.

Glad to hear Jeppesen was responsive to your input.





-- Edited by Marin on Friday 24th of February 2012 01:52:01 PM
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Old 02-24-2012, 01:11 PM   #4
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RE: C-Map Cartography Discrepancies

Marin,

My C-Map Max card is dated May 30, 2011 so it's strange that your older version would be more accurate than a newer release. I'm running it through a "big" Standard Horizon CP500 plotter (which I quite like) and a smaller North Star unit up on the flybridge. *

Just makes you wonder about the accuracy of some of the other off-the-beaten-track charts included in the dozens that are on that Max card. The irony is that I know my own area so don't really need the plotter -- it's the areas I don't know that I want to be able to trust the plotter cartography and now have some doubts.*

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Old 02-24-2012, 01:21 PM   #5
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RE: C-Map Cartography Discrepancies

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saturnaisland wrote:
Marin,

My C-Map Max card is dated May 30, 2011 so it's strange that your older version would be more accurate than a newer release.

*
*C-Map has gone through some changes since our original NT+ cards were burned in 1998 including the transition to Jeppesen which of course is a division of Boeing.* This plus the continuing evolution of new cartography and card formats presents all sorts of opportunities for human error, which I would not be surprised to learn was the cause of the error you have found.
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Old 02-24-2012, 06:42 PM   #6
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RE: C-Map Cartography Discrepancies

Quote:
Old Stone wrote:
Again, this is why your post is so worthy, and not wordy. Many thanks for opening it.
You're welcome, Carl.

Understand about the computer graphics pros & cons as I used to do photography and graphic design back*in the days of pin-registered overlays and multi-layered graphics. The computer looked like it was going to make work easier (and it did) but gliches were common and often harder to correct than handwork. In this case it seems that all the "overlays" are accurate but the background chart is out of register.*

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Old 02-24-2012, 08:04 PM   #7
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RE: C-Map Cartography Discrepancies

I use a 2011 C-Map Max Canada West card in a Furuno Navnet 2 plotter, and for the most part it seems to be quite accurate in the Desolation Sound area.*

However, when in close proximity to anything I'm more reliant on the depth sounder, radar (sort of) and eyeballs.*

I did observe after an overnight in Pendrell Sound that my plotter path (from my previous day's anchoring shenanigans) had me up on the beach and in the trees, which I think I would have noticed.

My plotter seems to "flash" every few minutes, which may or may not be attibutable to the card. In our previous Lowrance plotter the Navionics card seemed to perform flawlessly.
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Old 02-24-2012, 08:39 PM   #8
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C-Map Cartography Discrepancies

My Humminbird plotter uses a "C-Map" SD card with the BC charts. I bought it a few yrs ago, 2009 or 10 at the latest. It hasn't shown me any inaccuracies in the Gulf Islands, so I think it must be just the edition you are quoting that is not accurate. When navigating places that I haven't been before, visual is the way I go, when close in, so a 200 yd error would be obvious.

*

My main nav computer uses CHS charts, which I have always found to be right on the money.


-- Edited by koliver on Friday 24th of February 2012 09:40:14 PM
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Old 02-25-2012, 05:54 AM   #9
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RE: C-Map Cartography Discrepancies

I used plotters and charts of various manufactures on deliveries. Discrepancies and errors are not that uncommon. Always nice to be able to overlay the radar on the chart to make sure you're not headed into town.
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Old 04-20-2012, 12:20 PM   #10
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Resurrecting this thread just to report that Jeppesen contacted me today to say they have corrected the chart problem and are sending me an updated version of the C-Map card. This within two months of my original contact with them. Impressed.
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