FAQ

A nautical chart is a two-dimensional graphic of a 3-D world. It represents part of the spherical earth on a plane surface. It shows water depth, the shoreline of adjacent land, prominent topographic features, aids to navigation, and other navigational information.

The navigator uses the chart to plot courses, ascertain positions, and view the relationship of the ship to the surrounding area. It helps the navigator avoid dangers and arrive safely at the desired destination.

Paper nautical charts can be purchased from a NOAA certified chart agent. It is easy to order a chart online or by telephone and have the chart delivered to your door.

NOAA certified nautical charts and other nautical products meeting U.S. Coast Guard carriage requirements are available from the following sources:

• NOAA ENC® - can be downloaded for free from our website or purchased from a certified ENC distributor.
• NOAA Paper Nautical Charts - can be purchased from any NOAA certified chart agent.

A nautical chart presents the coastline taking into account varying tidal levels and water forms. A map, on the other hand, emphasizes landforms.

U.S. Chart No. 1 describes the symbols, abbreviations and terms used on all NOAA, NGA and international nautical charts, as well as the symbols used to portray NOAA ENC® charts on an ECDIS.

A raster navigational chart (RNC) is a digital image of the corresponding NOAA paper nautical chart. The information is stored as raster data - rows and columns of color pixels. The pattern of the colored pixels gives shape to the individual features on the chart.

An electronic navigational chart (ENC) is a digital chart database stored as vector data - pairs of coordinates that define the position and shape of points, lines, and area features.

Visit the NOAA Chart Locator to find paper nautical charts and electronic navigational charts (ENCs). The locator can also be used to identify the appropriate Coast Pilot volume to use in a particular area.

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.

The United States Coast Guard issues Local Notices to Mariners, providing up-to-date important navigational information. The National Geospatial - Intelligence Agency issues weekly the U.S. Notices to Mariners for larger vessels, such as those operating in 12 feet of water or more. NOAA's Weekly Chart Updates provide information about chart corrections.

Use the NOAA Chart Locator to find the chart that you are interested in. Then look under the "Available Products" section of the Map Selection Information panel on the right side of the Chart Locator window. Click the "PDF" button to download a full-size nautical chart or click the "BC" button to download an 8.5" x 11" BookletChart™ to your computer. Full-size PDFs can be printed on a large format plotter; BookletCharts can be printed on an ordinary home or office color printer.

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

NOAA's nautical charts are in the public domain. You may use then for any purpose free of charge, with two exceptions:

1. Paper charts that fulfill chart carriage requirements for regulated commercial vessels under Titles 33 and 46 of the Code of Federal Regulations must be purchased from NOAA-certified vendors.
2. Commercial printers must be certified by NOAA to sell navigational charts and publications that are "published by the National Ocean Service."

When republishing a NOAA chart or a portion of a chart image, we request the citation, "Provided by NOAA Office of Coast Survey, nauticalcharts.noaa.gov" be used, although this is not required. More information on how copyrights apply to government publications can be found at U.S. Government Works.

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 10900.6. 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(82)
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 the Coast Survey website are free.

NOAA ENCs may also be obtained from NOAA certified ENC distributors who provide global ENC distribution services. These companies may charge a fee for this service.

The source documents used to compile and maintain paper charts and ENCs are the same, but a paper chart is a static representation, while an ENC has 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 on a weekly basis. This includes relevant USCG Local Notice to Mariners and NGA Notice to Mariners.

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).

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 that wants to support NOAA ENC data can create applications that use it.

You can see a seamless display of NOAA ENCs with the NOAA ENC® viewer, however, this online chart display and images captured from it are not suitable to be used for navigation.

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 the paper chart 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.

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 for submerged wrecks and obstructions in the coastal waters of the United States, including geographic coordinates, can be obtained from NOAA's Automated Wreck and Obstruction Information System (AWOIS). AWOIS contains supplemental textual information including coordinates for items of navigational significance charted on NOAA nautical charts but is not designed to be a comprehensive list of all shipwrecks in any given area. Note: AWOIS data is no longer updated by NOAA. It is provided for informational purposes only and is not an authoritative source of information.

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.