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  1. #1
    Join Date
    Sep 2005
    Location
    Medway
    Posts
    231

    Exclamation Many dangerous errors in new Navionics cartography

    Shock, horror! On Sunday night, coming up the Medway in the dark, navigating with my iPad and watching out for the big iron mooring buoys, I noticed some weird features on the Navionics charts, for which I have downloaded the latest updates.

    You can check the Navionics cartography for yourself on their free web app here: http://webapp.navionics.com/#@13&key=ip%7BxHigdC
    a. Supposedly there are three mooring buoys (one is a “group of 3”). The one labelled "B.7" just NW of Stangate Spit shows at moderate zoom, to see the other two you have to zoom in a bit. I'm pretty sure none of these exist and never have.
    b. The drying patch at bottom left (by Sharp Ness) does not exist and the depths along the shore of Burntwick Island are shown much too shallow.

    Pan to the south and east a bit, around Stangate/Queenborough area, and you will see many “rocks” close to the HW mark. They are suspiciously evenly spaced. I don’t believe any of these exist, even allowing for a wide interpretation of what a “rock” might mean in the local context.

    It’s only because of my detailed local knowledge that I noticed these anomalies. In an unfamiliar place it could be very misleading, which kind of defeats the object of having charts, does it not?

    I have some experience of geographic data and map making but can’t understand how such errors could occur since the cartography must surely come from UKHO and the sources (harbour authority, Trinity House etc) would be the same as for other charts. Navionics does have a “community edit” feature but such additions are shown with a small “+” sign.

    However Navionics have recently introduced an add-on called “Sonar Charts” which I understand is bathymetry based on user-reported depths, Though I have not knowingly opted for this feature it might explain the potentially dangerous incorrect depths shown. A friend who has an older Navionics app on his Android phone seems to get more believable cartography than I see on my Android phone, iPad and PC.

    There does not seem to be any way to find out the source of Navionics cartography or to report errors, other than “community edit” features. Does anyone else know?

    I have not seen anyone report this kind of error yet on YBW.COM but the French have (see St Vaast/Tatihou example):
    http://blog.francis-fustier.fr/en/la...le-dangereuse/

  2. #2
    Join Date
    Aug 2003
    Location
    Swale/Medway
    Posts
    4,357

    Default Re: Many dangerous errors in new Navionics cartography

    When you wrote to me about this yesterday I didn't notice that those 'rocks' are plentiful on the Medway too.
    Incidentally I pointed out that the Swale No.4 buoy was missing from the screen shot off your iPad, but I see that it is present on the Webapp chart.
    Keep up to date with 'East Coast Pilot' at www.eastcoastpilot.com

  3. #3
    Join Date
    Sep 2003
    Location
    Cambridgeshire
    Posts
    1,391

    Default Re: Many dangerous errors in new Navionics cartography

    There is a buoy shown on the Navionics electronic and Imray paper charts in the Wash. It is shown on all the latest updated charts and all the charts preceding them. To my local knowledge it has not been there for at least 8 years..... certainly much longer.

  4. #4
    Join Date
    Apr 2009
    Location
    Essex
    Posts
    178

    Unhappy Re: Many dangerous errors in new Navionics cartography

    Looks like the sonar charts are completely messed up.

    Screen Shot 2015-09-08 at 20.53.17.jpg

    Compared with the normal view.

    Screen Shot 2015-09-08 at 20.57.41.jpg

  5. #5
    Join Date
    Aug 2007
    Location
    Me Glasgow, boat Kip in winter, Craobh in summer
    Posts
    270

    Default Re: Many dangerous errors in new Navionics cartography

    I will stick with my Rastor Memory Map charts, since they are effectively copies of UKHO paper charts, much safer since dangers are not "hidden" when zoomed out.
    Angus

  6. #6
    Join Date
    Dec 2013
    Location
    West Mersea
    Posts
    302

    Default Re: Many dangerous errors in new Navionics cartography

    I have never understood how Navionics achieve a reduction to chart datum with their user supplied data. Seems to me to be a pretty massive job.

  7. #7
    Join Date
    Jan 2007
    Posts
    12,272

    Default Re: Many dangerous errors in new Navionics cartography

    Quote Originally Posted by Tiller Girl View Post
    I have never understood how Navionics achieve a reduction to chart datum with their user supplied data. Seems to me to be a pretty massive job.
    It has to be an automated process, there's no way it could be otherwise. For that reason alone I don't turn sonar charts on, far too many possibilities for errors

    I wish navionics would concentrate on getting the core data and functionality right instead of constantly trying to add knobs, bells and whistles!

  8. #8
    Join Date
    Nov 2009
    Location
    Southampton
    Posts
    35,519

    Default Re: Many dangerous errors in new Navionics cartography

    Quote Originally Posted by Alpha22 View Post
    There is a buoy shown on the Navionics electronic and Imray paper charts in the Wash. It is shown on all the latest updated charts and all the charts preceding them. To my local knowledge it has not been there for at least 8 years..... certainly much longer.
    All the charts and pilot books refer to a set of visitors' moorings in the mouth of Langstone Harbour that don't exist either.

    Pete

  9. #9
    Join Date
    Jan 2005
    Location
    Me Edinburgh, boat JWD
    Posts
    5,115

    Default Re: Many dangerous errors in new Navionics cartography

    Maybe there's a reason why the "Not for Navigation" get out statement appears when you switch on.

  10. #10
    Join Date
    Dec 2013
    Location
    West Mersea
    Posts
    302

    Default Re: Many dangerous errors in new Navionics cartography

    Quote Originally Posted by Erbas View Post
    It has to be an automated process, there's no way it could be otherwise. For that reason alone I don't turn sonar charts on, far too many possibilities for errors

    I wish navionics would concentrate on getting the core data and functionality right instead of constantly trying to add knobs, bells and whistles!
    Well you know I am a luddite but the forumula that would convert that into an automatic process is massively complicated. I spend hours comparing and contrasting data from various sources to get it right for a relatively tiny area of sea. The more that formula is short-cut, the more inaccurate and pointless it becomes.

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