FAQ

A nautical chart is a specific type of map designed for marine navigation. Like other types of maps, it portrays a portion of the spherical Earth projected onto a flat two-dimensional surface. Nautical charts may be digital, such as the NOAA electronic navigational chart (NOAA ENC^®) or paper.

Nautical charts show shoreline, water depths and the nature of the bottom, landmarks, elevations and other topographic features, dangers and aids to navigation, such as buoys, beacons and lights, and other navigational information.

Navigators use charts to plot courses, determine a ship's position, and review the nature of the area along a ship's course. It helps the navigator avoid dangers and arrive safely at the desired destination.

NOAA no longer produces traditional paper nautical charts, but custom paper charts may be created from NOAA ENC data with the NOAA Custom Chart application. For help getting started, refer to NOAA's Quick Start Guide, How to use the NOAA Custom Chart Application video, or the resources listed under the "Guides" tab of the application.

Charts, such as nautical charts and aeronautical charts are distinguished from other types of maps by providing information specially for navigation by sea or air, respectively. They are typically used to plot, or "chart," a course from one place to another by drawing directly on the chart, noting the bearing and distance along each leg of the journey.

U.S. Chart No. 1 describes the symbols, abbreviations and terms used on all NOAA, National Geospatial-Intelligence Agency and international nautical charts, as well as the symbols used to portray NOAA ENC charts on an electronic chart display and information system (ECDIS).

The NOAA Chart Locator provides a map showing the locations of all NOAA ENCs, which may be downloaded individually in the Chart Locator or in larger groups on the NOAA ENC Download webpage.

Coast Survey cartographers apply thousands of changes to NOAA charts every year. Some changes are minor, but many are critical to safe navigation. Those critical updates can include new shoals, wrecks, and obstructions, and the latest changes to navigation aids. Additionally, shorelines are changing all the time, due to natural forces, storms or infrastructure improvements.

NOAA's Historical Map & Chart Collection contains over 35,000 images — cancelled nautical charts, maps, sketches, and more — that are available free to the public.

These historical charts are in the public domain and may be used for any purpose free of charge. When republishing a NOAA chart or a portion of a chart image, we request the citation, "Provided by NOAA Office of Coast Survey" be used, although this is not required. More information on how copyrights apply to government publications can be found at: www.usa.gov/government-copyright.

For help getting started, refer to the Historical Chart Collection short video tutorial.

NOAA's Historical Charts Collection has chart catalogs that provide images of the extents of NOAA's retired paper charts. To preview or download the chart catalog for your geographic region, under Search Criteria select "Chart Catalog" under the "Type" dropdown menu. Please recall that once a chart has been cancelled, it is not intended or safe for navigation

NOAA electronic navigational charts (NOAA ENC®) are vector data sets that support all types of marine navigation.

Electronic chart systems (ECS) encompass many electronic systems that display digital chart data. The chart data can be vector or raster. No specific format is currently defined, although many ECS can use NOAA ENC data. The Radio Technical Commission for Maritime Services (RTCM) has published Standard for Electronic Chart Systems, RTCM 10900.7. The USCG now allows most commercial vessels on domestic voyages to use an ECS with NOAA ENCs for navigation without paper charts.

Use of an electronic chart display and information system (ECDIS) with ENC data is required for large commercial vessels on international voyages. ECDIS are certified to comply with several international standards, some of which are listed below.

1. IHO Transfer Standard for Digital Hydrographic Data, IHO S-57
2. IHO Specifications for Chart Content and Display aspects of ECDIS, IHO S- 52
3. IMO Performance Standards for ECDIS, MSC.232(106)
4. ECDIS - Operational and performance requirements, methods of testing and required test results, IEC 61174

You can download individual NOAA ENCs from the NOAA Chart Locator or by region from the ENC download page. NOAA ENCs downloaded directly from these Coast Survey websites are free.

NOAA ENCs may also be obtained from the International Centre for Electronic Navigational Charts (IC-ENC) through a Value Added Reseller. IC-ENC charges a fee for this service.

Each ENC is a digital database that stores the NOAA nautical chart features and their location, shape, and attributes. They are published in the format of the International Hydrographic Organization S-57 Standard. They require an electronic chart system that reads and displays the data and are only intended to be used in their electronic form.

Historically, a sophisticated navigational computer called an Electronic Chart Display and Information System, or ECDIS, was required, however, ENCs can now be used on simpler electronic chart systems and chart plotters.

The NOAA ENC^® Viewer provides a seamless display of NOAA ENCs similar to how the data is portrayed in an ECDIS, however please note that the viewer or images captured from them are not suitable to use for navigation.

For help getting started, refer to the Electronic Navigational Charts Online Viewer short video tutorial.

ENCs were originally digitized from NOAA paper nautical charts. New source documents are now used to compile and maintain ENCs independently. Traditional NOAA paper nautical charts are no longer produced or maintained. The online NOAA Custom Chart application can be used to create custom paper charts derived from NOAA ENC data. Each custom chart is a static representation of the ENC data from which it is derived, while the digital ENCs have layers of data that can be turned on and off in the chart display and interact with the navigation system to provide warnings and alarms of dangers. The display of ENCs is also often simpler and less cluttered than the portrayal rendered on a paper chart.

NOAA obtains data from a number of chart data sources. The primary ones are water depths and the identification of wrecks, rocks, and other obstructions from NOAA's Hydrographic Surveys Division, depths within federally maintained channels from the U.S. Army Corps of Engineers, delineation of shoreline from NOAA's National Geodetic Survey, and positions, types, and characteristics of aids to navigation (buoys, beacons, and navigational lights) from the U.S. Coast Guard.

All NOAA ENCs are under continuous maintenance. As new source data is received by NOAA, it is evaluated, compiled, and released to the public every weekday evening. This includes relevant USCG Local Notice to Mariners and NGA Notice to Mariners.

Our NOAA Navigation Updates Application visualizes where critical corrections to charts have occurred over a given time period for a specific area.

Official NOAA ENCs meet U.S. Coast Guard carriage requirements, as defined in Title 33 and Title 46 of the U.S. Code of Federal Regulations (CFR), and as specified in USCG Navigational and Vessel Inspection Circular No. 01-16 (NVIC 01-16).

The U.S. Coast Guard is responsible for establishing and enforcing chart carriage requirements and has asked NOAA to direct the public to send all questions and comments regarding nautical chart carriage requirements to the USCG Navigation Center at: https://www.navcen.uscg.gov/?pageName=contactUs.

Display of NOAA ENC depends on navigation software such as an ECDIS, which conforms to international standards. However, the NOAA ENC is not dependent on unique operating systems or navigation software. Since it is provided in a standard format, any navigation software company choosing to support NOAA ENC data can create applications that use it.

There are a wide variety of navigation apps and programs that use NOAA ENC data. While some use ENCs in their native format, many producers have put this ENC data into their own proprietary format. As a result, they control how and when NOAA chart updates are incorporated into their program. We encourage all mariners to make sure they understand how NOAA updates are incorporated into the specific application they decide to use.

The NOAA ENC® Viewer provides a seamless display of NOAA ENCs similar to how the data is portrayed in an ECDIS. The NOAA Chart Display Services portrays NOAA ENC as it would appear on a traditional paper nautical chart. Neither of these viewers or images captured from them are not suitable to use for navigation.

A brief video tutorial on using this tool is available on NOAA's YouTube site here: https://www.youtube.com/watch?v=SgIrHCbSBY0

Each ENC has an Update Application Date, an Issue Date and various Cleared Dates. For more information, see ENC dates.

Yes, every NOAA ENC starts with a file header that contains information about that particular ENC, including edition number, issue date, and update application date.

CATALOG.031 - lists of the cells and ancillary files that are included in an NOAA ENC "exchange set."

README.TXT - lists all of the NOAA ENCs with their corresponding paper/raster chart number, title and other information.

Ancillary files - text files that are analogous to chart notes on paper charts or possibly information from the United States Coast Pilot^®.

Image files - a picture that links to a feature(s) on the NOAA ENC, such as a picture of a bridge.

They are both vector format charts. However, the NOAA ENC is based on the International Hydrographic Organization Transfer Standard for Digital Hydrographic Data, Publication S-57 and is approved by the International Maritime Organization for SOLAS class vessels to use for navigation in ECDIS. The DNC is based on the Vector Product Format Standard, which is a NATO standard for digital military map and chart data. More information about DNCs can be found at the National Geospatial-Intelligence Agency.

NOAA's Marine Chart Division is actively rescheming and improving NOAA ENCs to create a new layout of rectangularly shaped charts at a set of consistent scales. This effort will result in a more consistent suite of coverage with improved detail in many areas. This will result in larger standard scale coverage and resolve discontinuities in adjacent ENCs. Our ENC Rescheming Status Interactive Map shows our current progress.

Please refer to our GIS Data & Services page to learn how to download ENC data in alternate formats or to display ENC data seamlessly within a Geographic Information System

A brief video tutorial on using this tool is available on NOAA's YouTube site here: https://www.youtube.com/watch?v=SfH-fQQWM_w

The International Hydrographic Organization defines hydrography as "the branch of applied science which deals with the measurement and description of the physical features of the navigable portion of the earth's surface [seas] and adjoining coastal areas, with special reference to their use for the purpose of navigation."

A hydrographic survey supports a variety of activities: nautical charting, port and harbor maintenance (dredging), coastal engineering (beach erosion and replenishment studies), coastal zone management, and offshore resource development. Hydrographers use sound (SONAR) and light (LIDAR) to 'see' the bottom of the ocean. The primary information obtained by hydrographic surveys are water depth and potential existence of dangers to navigation. A hydrographic survey also helps determine the nature of the sea floor material (i.e. sand, mud, rock), which is important for anchoring, dredging, structure construction planning, pipeline and cable routing, and fisheries habitat mapping.

National Ocean Service hydrographic and bathymetric data is available from the National Centers for Environmental Information (NCEI).

Information on NOAA's Current Year Survey Plans.

NOAA's Office of Coast Survey primarily surveys U.S. coastal waters. The U.S. Geological Survey and the U.S. Army Corps of Engineers survey inland rivers and waters.

NOAA's Center for Operational Oceanographic Products and Services predicts and measures tides, water levels, and currents.

Shoreline information and data is available from NOAA's Office for Coastal Management and the National Geodetic Survey.

T-sheets can also be found in the Index of Non-Georeferenced Manuscripts and some can be found in NOAA's Historical Map & Chart Collection. To search the Historical Map & Chart Collection: Under Search Criteria select "T-Sheet" from the "Type" dropdown menu.