Navionics Gold Charts

[panther]

Just moved to Navionics gold charts from Garmin Bluecharts that I used to use on the RIB

On my first trip out from Portishead with the new chartplotter I found 2 major bouys that were missing from the electronic chart

Chart XL3 - G24

EW Grounds - Racon Bouy (major bouy in the Bristol Channel)
N Elbow.

I have filled in the discrepancy form on navionics website - Was I just unlucky!! - have others found bouys missing on charts (any make)?

Cheers
Jools

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[LeytonC]

I use C-Map NT+ and both are in mine!

Talking of strange things, why does the RYA/admiralty chart plotter thing, split 2 chart areas in the middle of the bristol channel? i had a look on the site, saw this and closed the window, i know chart areas need to be created, why not make it lands end to st. davids head?

<hr width=100% size=1>Thanks

Leyton

EXTAR Software - Software that works for you
Phone : 07803 139 736

 

[Marsupial]

I have C charts on a raymarine plotter and there is so much missing and so much out of place - like france has moved 200 metres to the left if you calibrate the thing spot on in Dover - that I wont use it for anything other than planning. Lets say at best I find them "creative", at worst down right scary. But then again some paper charts are economical with the detail, suggest you compare "yachtsmans charts" of stone point (near Walton) with a proper admiralty version, and you find that there is not as much water down there as you think!

You guessed I am not impressed with electronic charts, in summary, a nice toy for the boat show.

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[gonfishing]

I guess that's common sense and we can't have any of that now can we!!

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[jfm]

It must be your kit or set up marsupial? I have used Cmaps all around Ireland, S Coast UK, N coast France, and the Med, and they're always spot on. When I'm parked they show me right on the actual pontoon that I'm parked on, even without differential

Also I wonder what you mean by "calibrate in Dover". Once the correct datum is in there I have never nudged/calibrated the picture

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[tcm]

um, well, I have used all sorts of garmin/navionix and also cmap, and they show super detail, no "calibration" needed other than letting them get a fix and they show exact part of pontoon. Same as car gps systems, they are 5-10 ish metres accurate in my experience.

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[steverow]

Agree 100%.
C-map is the only one I would rely on. They've been at it the longest, have a huge commercial shipping userbase and bags more experience than some of the newer market entrants.
My C-map is always spot on with superb detail.

Steve.

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[BrendanS]

At the end of the day, they all come off the same basic cartography in the regions most of us boat in, so very little difference between them in terms of geographic positioning etc

The differences are primarily in the presentation, scope, and positioning and presence of up to date info like buoys.

<hr width=100% size=1>Me transmitte sursum, caledoni

 

[sailorman]

i use raytheon radar / plotter with C-map both in France & Holland if we go through a "Lock" the track is straight thoough the middle. no probs

<hr width=100% size=1>Mines a Crocodile sandwich & make it Snappy

 

[Deleted User YDKXO]

I had Navionics charts on my last boat and I found them inferior to the C Map charts in general. Is this chart the largest scale chart you can get from Navionics for the area or is it a general passage chart?

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[Talbot]

I would urgently recommend that you check the datum that your plotter is set too, as this is the most likely reason for your discrepancey. Make sure that it is set to WGS84 - there should be no reason for any adjustment elsewhere (my plotter does not give any ability to do this anyway).

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[Oldhand]

One could re-ignite the vector vs raster argument here! Minimal manual input to producing a raster chart from the original paper chart therefore minimal errors...


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[duncan]

the navionic gold's contain all the chart detail available for any particular area as I understand it.

obviously the plotter will be set up to show certain details at certain zoom settings but I am sue his buoys aren't missing 'cos of that (or he would be missing them all!)

I don't have any problems with mine, or the GCharts that were based on earlier Navionics, but do find buoyage inconsistent - ie a later chart will have been 'corrected' over an earlier one by removing a buoy that is still there!

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[panther]

Thanks Talbot - No the Datums fine!

All the other bouys are in the right place, I'm just missing 2 fairly major bouys in the middle of the Bristol Channel:-

EW Grounds - A Safe Water Racon bouy
51 27.1N, 2 59.9 W
N Elbow
51 26.9N 2 58.6 W

There are a few others in the same vicinity that are marked - The radar picked them all up and overlayed on the chart fine, so I'm sure the Datums fine - they are just not marked!!

Chart is the new XL3 - 24G, zooming makes no difference either!

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[hlb]

Ive got an old Raythion thingy C Map I think. It just works. I can tell if they have put the pontoon in the right position each year!! Never found it out in the last five years or so. It's good for 5 or 6 ft. Close enough for me.

<hr width=100% size=1> No one can force me to come here. I'm a volunteer!!.

Haydn

 

[Marsupial]

JFM and TCM

Using the C charts in my Raymarine plotter I find that the charts are "OUT" by a couple of meters in Dover, I can adjust the position so I can accuratley show the position of the GPS in relation to the pontoon - FANTASTIC, turn the boat round in the berth and I can tell its turned round looking at the plotter - is that great or what?

BUT then I went to Boulogne - (or how ever they spell it) - sort of due southish from dover.

Same boat, same plotter same c chart NO changes in any setting.

Imagine my dismay when we arrived and I found that I had just tracked along the railway line and tied up in the yacht club bar! Being a law abiding type I went out on deck to get a platform ticket and order a beer, but there wasnt anybody around - we were still in the marina, on a hammer head at the end of a trot.

The conclusion I reached - which may be wrong is that during my crossing somebody had moved france - that MUST be the only answer cos C Charts say they are accurate and so does Raymarine.

But why then - does my yeoman plotter (kit I use), which uses the same GPS engine show my position correctly everywhere I go from my base in Dover. Then on charter holiday coupled to a Garmin handheld it is has been correct in these places: the BVI, Thailand, Greece, Turkey and even (I am ashamed to admit) the solent?

I need to rethink my orginal conclusion, It must be the C Chart that is wrong, PM me an address I will GIVE it to you.

David

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[duncan]

pleased you bought a platform ticket as we wouldn't want to upset our friends over there.........../forums/images/icons/smile.gif

I am afraid I would draw a different conclusion on the information given - namely that the chart and plotter are on different datums and that whilst you have 'adjusted for Dover' that adjustment will not necessarily aply elsewhere.
Other than that I wonder if teh french railways are creating a GPS anomally to increase ticket sales (but then the Yeoman would be similarly affected)

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[jfm]

David:
I dunno, can't explain. Need to think about it. Did you by any chance rig up the Yeoman on that very same trip - I'm wondering if your trip to Boulogne happened to coincide with one of those periods of a few hours when the GPS system was wonky? If so, the Yeoman would also show an error. But I'm guessing here, can't explain the symptoms you describe

Is your GPS set differentially corrected or are you just running normal GPS?

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[Marsupial]

Duncan

The truth is that on that ocassion "C Charts" used two different datums on the same digital image - they admitted it to me at the boat show - is this thing a toy or what?

BUT NOWHERE DID they declare it - WGS84 is what it said on the box and that was true for the UK but NOT for France which was something different - the Italians who made the chart didnt give a @@@@ so that is why I am very sceptical about the accuracy and precision of the datum alignments on electronic charts - how do you know if its right? - unless you have already arrived and have something "concrete" to compare your position to - or you compare the electronic chart with a trusted paper version which is what I do Admiralty + YEOMAN.

As regards detail try going up the twizzel using C charts, you will encounter a sand bar that is not on the chart - but it is on the admaralty chart, and on the old ones its been there years aparently - spent an afternoon there waiting for the tide to come in and lift me off! Other skippers were asking if I was aground because I was in the middle of a bouyed channel - yes I was - and the "feature" I was stuck on was only identified later at a super low spring - but there it was plain as can be on the admiralty chart - I bought the week after.

I rest my case

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[Talbot]

Comment on the datums was aimed at Marsupial who was claiming distance discrepancies. datum change wont replace missing features, but is the single commonest reason for errors in position. Hopefully your buoys will be replaced at the next update, but I would be careful about buoys on charts unless you keep a very good check on notices to mariners. Buoys get moved around, or break away, or lights changed and thus your chart may be incorrect on these features. Land tends not to change quite so frequently!

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