An ENC (Electronic Navigational Chart) is a special type of vector chart. The product has its own specification in S57, Appendix B1. ENC is primarily intended for use in ECDIS (Electronic Chart Display and Information System) to promote safety at sea. The electronic charts produced by the Swedish Maritime Administration that may be used in type-approved ECDIS instead of paper charts are designated Official ENC.
ECDIS combine components such as ENC, GPS receiver, radar, autopilot, etc., allowing the vessel’s position to be plotted directly on the chart display on the screen. Using known parameters such as course, speed and the vessel’s draught, the system can perform other functions including issuing a warning when the vessel is approaching shallow waters.
The use of digital charts instead of paper charts is governed by international rules. The equipment shall meet the Revised performance standards for electronic chart display (ECDIS), IHO directory (the purchase of standard).