Charts, ECDIS and nautical publications
Carriage of charts and nautical publications
All ships should carry adequate and up-to-date official nautical charts, sailing directions, lists of lights, notices to mariners, tide tables and all other nautical publications necessary for the intended voyage.
An on board chart and publication management system is recommended to ensure that records are kept of what charts and publications are carried, and when they were last corrected.
Official nautical charts
Official nautical charts can be either paper or electronic charts produced by, or on the authority of, a national hydrographic office.
Unlike paper charts, electronic charts need to be displayed on an electronic chart display system. Official nautical charts can be in one of two electronic formats:
· Electronic navigational charts are official vector nautical charts. When displayed on ECDIS equipment they are equivalent to paper charts;
· Raster navigational charts are official raster nautical charts. British Admiralty ARCS format charts and United States NOAA format charts are examples.
Use of charts and nautical publications
Only official nautical chart data, which is up-to-date and adequate. should be used for passage planning or navigation. The charts can either be paper charts, or electronic charts that are equivalent to paper charts. All other chart data should only be used as a supplementary navigation tool.
For advice on planning using a combination of electronic and papers charts refer to section.
When navigating using electronic charts, care should be taken to ensure that the display shows sufficient 'look-ahead' distance and the next chart can be readily accessed.
Electronic charts and electronic chart display systems (if fitted)
Electronic charts can either be in vector or raster chart format. The mariner using electronic chart systems should be aware of the differences between the two types of chart formats.
Vector chart format electronic charts
Vector charts are compiled by attributing to each and every chart feature a set of values, and each chart feature is stored in a layered digital database. Storage in a database allows the chart data to be displayed as a seamless chart, while layering enables fields of data that are not required at the time to be removed from display to reduce chart clutter.
Chart features can be interrogated to display additional information about charted objects.
The inherent intelligence of vectorised charts allows three dimensional route safety zone monitoring. Chart depth contours and air draught clearances around the ship can be automatically monitored, both while the route is being planned and while the ship is on passage. Alarms will automatically be triggered if a safety zone around a ship is breached.
Raster chart format electronic charts
Raster charts are exact copies of paper charts and are produced by digital scanning techniques. Information on raster charts cannot be layered, and the move from one chart to another will not be seamless. Raster charts have to be individually selected and displayed.
