Hydrographics
From CruisersWiki
The Cruiser’s Wiki guide to finding Nautical Charts
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Finding the right chart to include on a wiki page can take some research. There is no international system (yet) and so hydrographic charts of various countries can have some or all of the information.
Common hydrographic agencies are:
- UKHO (UK) -- commonly known as Admiralty charts.
- NOAA (US)
- CHS (Canada)
- LINZ (New Zealand)
- DHN (Brazil)
- SHN (Argentina)
- AHS (Australia)
... as well as many military and historic sources.
Paper Charts
Paper charts are still considered the gold standard of navigation, and many cruisers rely on them exclusively. In this day of decreasing cost of electronics, even cruisers who rely almost exclusively on electronic chars usually have a set of paper charts as a backup.
Paper charts are produced directly by the above agencies, and are frequently sold through retailers such as chart agencies. A quick search of the business telephone directory or local internet business search guide, or google, will reveal a list of chart agencies in your area. In general, Admiralty paper charts or the USA charts from NOAA are the best to aim for, although the smaller national agencies also have a useful range of charts. For example the LINZ charts from New Zealand have a good reputation for the South Pacific region, where coverage is available (e.g. Samoa, Cook Islands or around New Zealand).
An increasing number of chart agencies now produce charts on demand, where the latest chart including any updates, notes to mariners, or other annotations, are produced via a high speed chart plotter directly from the agency when the paper chart is ordered. This provides some clear advantages in terms of accuracy of navigation.
Electronic Charts
Electronic charts primarily need to be compatible with the electronic device that you are using them for. There are many providers of electronic charts for chart-plotter type devices, such as:
Where a computer with software such as OpenCPN is being used, the charts can come in a number of different formats. The Chart Sources Page for OpenCPN discusses the various chart formats that are available, which formats are compatible with OpenCPN, and where to obtain the charts.
Another option is GPS or hand-held devices, which often come with in-built charts. Using cheap electronic charts on handheld devices is foolish, since they're based on small scale or outdated charts. If you value your yacht (and who doesn't?) always consult a proper chart with all the latest updates included. Many an otherwise competent sailor has lost his ship, crying that the rock, reef or sandbar they hit wasn't on the map. Don't let it happen to you.
Chart Segments in this Wiki
Above all, be careful with copyright when using charts in the wiki. A scanned image of a copyrighted paper chart, or a copy of an electronic chart from a commercial charting package, will almost certainly be subject to a copyright which means it cannot be used in this wiki.
A useful tool to start with is Google Earth which will allow you to find a city or port on the world globe. From there, a neat tool called GeoGarage will allow you to find maps for most places of interest, just by zooming in on that location and looking at the numbers on the chart overlays. These are not the latest charts, but those that the various agencies are happy to release to the general public, and Notices to Seamen should still be consulted for the latest variations. Coastlines don't change much over time, but navigation aids and channel markers do. Once you have that chart number, try UKHO search engine to get the full title and scale for your webpage.
If an area isn't covered by these tools then a Google search usually reveals some useful data.
Try to list the smallest scale for the terrain being discussed, there's no point listing large scale maps at the level of a continent. Australia, for instance, is completely covered by one chart at 1:10000000 scale and six charts at 1:3500000 scale. As we drill down to view state coastlines and even further to individual ports, the maps get more detailed.
Multiple sources can be listed on a wiki page if they are available. Often there is a British Admiralty chart for a region when nothing else can be found, and you can be sure that the US government has most charts as well. Both NOAA and NGA charts can be viewed online here.
Chart Categories
The Danish Hydrographic Office (KMS) categorizes the charts thus:
- Passage/landfall Charts
- Scale: 1:2.000.000 to 1:350.000.
- These charts cover very large areas and are only to be used when navigating across open seas or oceans. These charts contain very limited amounts of nautical and hydrographical information. Close to shore, this information is sometimes omitted completely.
- Coastal Charts
- Scale: 1:350.000 to 1:75.000.
- These charts contain detailed nautical and hydrographical information, enabling safe navigation through main waterways and straits.
- Approach Charts
- Charts in the scale between 1:75.000 and 1:30.000.
- These charts contain detailed nautical and hydrographical information in order to safely approach the harbours shown in the area. In narrow straits or confined areas or in areas where a special scale chart covers the area, a simplification can have been done.
- Harbour charts & Special scale charts
- Charts produced in a scale larger than 1:30.000.
- These charts covers areas which are difficult to navigate such as narrow straits, harbours or anchorages.
Chart Sources by Region
Australia
The Australian Hydrographic Service publishes both paper and electronic charts for the Australia region.
An index of the AHS paper charts is here: http://www.hydro.gov.au/webapps/jsp/charts/chartlist.jsp
AHS electronic charts are available in the AusENC product. This is S63 format which is compatible with OpenCPN versions 3.3 and later. Details are available about AusENC and about electronic charting.
AusENC charts are not purchased from the Australian Hydrographic Service directly but can be obtained from chart retailers such as Boat Books Australia.
New Zealand
Land Information New Zealand (LINZ) publishes both paper and electronic charts for New Zealand and much of the South Pacific region. Due to New Zealand's close ties with many Pacific Island states such as Samoa, Cook Islands and Tonga, these charts are often the best available for the waters of those nations.
LINZ make available a chart catalogue on line and both raster and vector formats. The raster charts are available for free download in a format that's compatible with OpenCPN. The vector charts have an on line catalogue and are available for purchase on line.
UK
The UK Hydrographic Office is arguably the world's largest producer of charts and has been for hundreds of years. Their chart coverage is world-wide. Their charts are often referred to as Admiralty or BA (British Admiralty) charts.
Note that some BA charts haven't been updated for some time. Especially in areas of the South Pacific, it's often the case that the LINZ charts are a better and more accurate source.
BA charts are produced in both digital and paper formats, digital charts are available in both raster and vector format. These are sold under the ARCS (Admiralty Raster Chart Service) and AVCS (Admiralty Vector Chart Service) brands. Note that both brands incorporate charts from other agencies such as the Australian Hydrographic Service. The vector format is S-63 / S57 which is compatible with OpenCPN.
An on line catalogue is available for download. Due to the number and breadth of BA charts, it's a significant download just for the catalogue.
BA charts can be purchased from a network of distributors world-wide. One such distributor with a comprehensive range of both vector and raster charts is Euronav in the UK, and another is ChartWorld in Germany. The producers of the OpenCPN plugin for the S63 format have an agreement in place with ChartWorld for the sale of compatible digital charts. In addition to the charts, a list of other digital publications is available including list of lights, radio signals, and tides.
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Names: Haiqu, Delatbabel |
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