Electronic charts are the next generation of navigational charts. Their use in electronic charting systems simplify traditional navigation processes such as route planning and chart updating, and also enable automation of route tracking through use of satellite positioning devices. These features can greatly enhance navigational safety by improving situational awareness, especially in busy or confined waters.
Digital technology is used to develop electronic charts from traditional paper charts and directly from marine survey data. The importance of using official data is, as with paper charts, absolutely paramount to maximising safety and other related benefits. Official electronic charts currently take two forms: Electronic Navigational Charts (ENCs) and Raster Navigational Charts (RNCs).
The difference between RNCs/ENCs
Raster charts are scanned images of paper charts. Each raster image consists of thousands of coloured dots (pixels) that together make a flat image on one layer. Each pixel is geographically referenced enabling real-time display of your vessel position when your chart system is linked to a GPS.
Vector Charts consist of digitised data that record all the relevant chart features such as coastlines, buoys, lights etc. Charts are made up of many layers of information representing these different objects and attributes, all of which are held in a database-like structure that allows them to be selectively displayed and queried creating the potential to manipulate the chart image when displayed on the the screen.