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Electronic Charts                                                               Home Page

see http://www.euronav.co.uk/Products/Charts/Charts.htm  for examples of Vector and Raster charts

SNC - Standard (Paper) nautical Chart

ENC - Electronic Nautical Chart

ECDIS  - Electronic Chart Display and Information System

Raster Charts are simply made by scanning a paper chart and then geo-referenced. The advantage of raster charts is that they are an exact replica of the original paper chart, with no change, or data being left off. The downside is that they are just an image, (a 'dumb picture') and cannot give the detailed information or screen management facilities a vector chart can give.  Can be over-zoomed to the point of unreliability.

They are relatively cheap to produce, and coverage is consequently very wide. They are large bit map files requiring a lot of storage.

Vector Charts   are a database containing details of the objects on the source paper charts, usually in several 'layers' of information.  You can click down through the layers to reveal more detail. Their appearance is different to paper charts and the chart data can be selected on or off in layers.  Zooming and scrolling from chart to chart is seamless.  Expensive to produce, but require less computer storage.  Together with GPS they can maintain depth and position alarms and be integrated with radar.

Either chart format can be used on a dedicated 'plotter' or on a laptop PC.

For a summary of the respective advantages see here:  Raster_vector  and here  http://www.chersoft.co.uk/nav_chartformats.htm

RASTER                                                                VECTOR (detail could be reduced)

Navigation software

Can be plotter or PC based; both require a feed from a GPS to display the vessel's position on screen.  The RYA / UKHO package is very simple and requires you to enter tide stream and rate; other packages contain tide tables and tide atlases which can be used for navigation and plotting.  More advanced packages will use weather forecast wind files (GRIB) see here. http://www.globalmarinenet.net/grib.htm

The software may maintain a log of position, speed and heading etc

RYA Training Plotter

Entry Screen – 9 Icons

CHART MANAGEMENT

 

  • Select chart
  • Properties of chart
  • Update
  • Datum
  • Display type
  • Find Position

WAYPOINTS

 

  • Add
  • Edit - delete
  • Display

ROUTES

 

  • List of routes
  • Cross Track Error

VESSEL VIEW

  • Vessel Fixed
  • Chart fixed

VESSEL DETAILS

  • Log
  • Heading
  • Track
  • Display

MEASURING TOOLS

  • (eg Plotter & Dividers)

  • One measure

  • Multiple measures

SIMULATION MODE

Set up:

  • Position of vessel

  • Speed

  • Heading

  • Tides

  • Stop / go / pause

  • Fast forward

  • Reset

OVERLAYS

Defines areas you wish to avoid

GO TO

Defines course of vessel to a new or old waypoint

Lower Icons

POSITION VESSEL

Place vessel in position on chart

[1 : 1] Zoom button

HELP !!

Posted Thursday 5th November 2009