What are ENCs?
Electronic Navigational Charts (ENC) are vector data sets that support all types of marine navigation. Originally designed for large commercial vessels using a sophisticated navigational computer called an Electronic Chart Display and Information System (ECDIS), ENCs are now also being used on simpler electronic chart systems and "chart plotters" on many types of ships and by recreational boaters. NOAA ENCs help provide real-time ship positioning, as well as collision and grounding avoidance.
NOAA ENCs comply with the International Hydrographic Organization ENC Product Specification. ENCs are produced around the world by many different countries' national hydrographic or charting agencies. NOAA maintains more than 1,000 NOAA ENC® datasets over U.S. coastal waters and the Great Lakes. The U.S. Army Corps of Engineers produces a similar product, called Inland ENC (IENC) for many U.S. rivers.
Updates for ENCs
Free updates for NOAA ENCs are available weekly, which provide critical changes as well as the routine addition of newly compiled data, such as hydrographic or shoreline surveys. The NOAA Weekly Chart Updates page shows the areas that have changed on each ENC since its last new edition was published.
ENC Data for GIS
ENCs also provide vector base maps for use in geographic information systems (GIS) that are used for coastal management and other purposes. The NOAA ENC Direct to GIS service supports extracting ENC data into GIS supported formats.