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NOAA introduces Zones of Confidence; mind your ZOC

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher since 4/12/2005, and now excited to have Ben Stein as a very able colleague. Panbo is going to the next level in 2018 and beyond.

4 Responses

  1. Sheldon Haynie says:

    Nice article Ben.
    Do you know how will they handle the areas where they actually dragged a weighted wire? I recall Penobscot had some of those, as a means of finding significant rocks to some control depth.
    Will those be (a separate) ZOC, or a different annotation?

  2. Dan Corcoran (b393capt) says:

    Two thoughts. The bay is little more than 1 mile deep from the entrance. Isn’t declaring the accuracy +/- 1600 ft, far far to cautious? With a clear nearby coastline you would think the surveyor knows were they are to within 160 feet. It seems the rating system is too simple, or could use a comment why they choose D.
    I went to activeacaptain to jog my memory of the area, and unexpectedly found the ZOC, but only in some views. Need to zoom in and scroll down and to the right of South Bay. If I had not read this Panbo entry, i would not likely have seen the ZOC, and really it was still luck that I noticed it. If you zoom too much or too little it can’t be found. I wonder what can make it more apparent to boaters?

  3. René van Quekelberghe says:

    Odd that the S-57 CATZOC description according IHO is slightly different with an A2 zone and also a U zone. I understand USCG and other providers were ‘kindly’ requested by IHO to put some effort into getting these CATZOCs included as soon as possible. IN ENC there are a lot of CATZOC U’s which stands for Unassessed. But for sure it is a good improvement as many navigators believe that when there is a cell or paper chart with a new edition date that all data is also from that date.

  4. Thanks, RenĂ©! A Google search for “CATZOC” yields many interesting finds. I did not realize how long the international cartography community has been working on how to better inform mariners about data quality. I also enjoyed finding some evidence that commercial and recreational boaters want this information:
    http://www.hydro-international.com/content/article/safe-navigation-with-uncertain-hydrographic-data
    https://www.iho.int/mtg_docs/com_wg/DIPWG/DIPWG2/TSMAD20_DIPWG2-13A_CATZOC_Symbols_and_Palettes.pdf
    The latter is definitely an inter-agency document, but the crucial bit is that 80% of 8,000 mariners polled by NOAA preferred a detailed survey date and CATZOC designation over the current star symbology (which I didn’t know about and haven’t noticed on the vector charts I use).

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