The carriage of an adequate portfolio of updated paper charts and Electronic Navigational Charts (ENCs) is mandatory for vessels specified under the Safety of Life at Sea (SOLAS) convention. It is essential that navigators fully understand their responsibilities regarding the update and maintenance of all chart products onboard. Nautilus Charts provides a variety of services that assist navigators with fulfilling their SOLAS responsibilities.

Regarding the chart subscription services available, please refer to “Web Distribution” in the Services section.

For a detailed discussion of ECDIS and charting issues, please refer to the S-66 publication from the International Hydrographic Organization (IHO). The IHO's "S-66: Facts about Electronic Charts and Carriage Requirements" is available for download from the IHO's website here.

Various charting authorities also publish detailed information about paper chart and digital chart products. These websites contain a variety of educational materials, videos, papers and other links. They include:

  • US National Oceanic and Atmospheric Administration to (NOAA)

  • Australian Hydrographic Service (AHS)

  • Canadian Hydrographic Service to (CHS)

  • Land Information New Zealand (LINZ)

For Frequently Asked Questions, please see the section below.

What are nautical charts?
Why Electronic charts?
What is an ENC?
How are ENCs distributed to end users?
What is a SENC?
What are RNCs?
What are Inland Electronic Nautical Charts (IENCs)?
What is an ECDIS?
What is the requirement for ECDIS?
What is the difference between ECS and ECDIS?
Why is it important to use official charts?
Can unofficial electronic charts be used for navigation?
Who produces and who sells ENCs?
What is the difference between a hydrographic chart and a topographic map?
What is a Datum?
What is a chart datum?
What is S-57?
What is S-63?
What is an ECDIS anomaly?
What does WEND mean?
Am I legally required to have nautical charts onboard?
Where do chart updates come from?
What is meant by 'print on demand' (POD) charts?
What are nautical charts?

Nautical charts are maps that depict the configuration of the shoreline and seafloor. They contain depths, nature of bottom, elevations, and characteristics of coast, dangers and aids to navigation.

Nautical charts can be in analogue form (paper charts) or digital form (electronic charts). Only charts issued by the authority of a government and official Hydrographic Office are classified as official charts and are authorised to fulfil carriage requirements. Other private charts are not permitted as tools for navigation under the IMO SOLAS convention.

Why Electronic charts?

Electronic charts are the next generation of navigational charts. Their use simplifies traditional navigation processes such as route planning and chart updating through digital technology, and also enables automation of route tracking through the use of satellite positioning devices. They enhance navigational safety by improving situational awareness, especially in busy or confined waters.

What is an ENC?

An electronic navigational chart is an official database created by a National Hydrographic Office for use with an Electronic Chart Display and Information System (ECDIS). An electronic chart must conform to standards stated in the International Hydrographic Organization (IHO) Publication S-57 before it can be certified as an ENC.

How are ENCs distributed to end users?

ENCs are available to end users in a protected format called IHO S-63. S-63 is designed to maintain the integrity of all transactions between service provider and end user. It also enables the end user’s systems to check the authenticity of the sent data. S-63 ENCs are usually distributed on CD because of the large amount of data.

What is a SENC?

SENC stands for System Electronic Navigational Chart. When an ENC is loaded into the system, it becomes a SENC. ECDIS converts ENC data into its own internal SENC format for optimal chart image creation. SENC data can differ between manufacturers.

Back to top
What are RNCs?

Raster navigational charts (RNCs) are raster graphics charts that conform to IHO specifications and are produced by converting paper charts to digital image by scanner. IHO Publication S-61 provides guidelines for the production of raster data.

What are Inland Electronic Nautical Charts (IENCs)?

Inland ENCs (IENCs) are official digital vector charts produced by inland waterway authorities in accordance with the International Hydrographic Organisation's (IHO) product specification S-57, extended for use on inland waterways. NOTE: The IENC standard is a superset of the ENC standard. Therefore, an ECDIS system will not normally display inland waterway specific objects and symbols correctly.

What is an ECDIS?

Electronic Chart Display and Information System (ECDIS) is a computer-based navigation system that complies with IMO regulations and can be used as an alternative to paper navigation charts. Integrating a variety of real-time information, it is an automated decision aid capable of continuously determining a vessel’s position in relation to land, charted objects, navigation aids and unseen hazards.

What is the requirement for ECDIS?

For an ECDIS to meet a minimum level of reliability and functionality, the IMO has developed a performance standard for ECDIS. This standard specifies how an ECDIS must work in order that it serves as an adequate alternative to the paper nautical chart. The IMO Performance Standards permit National Maritime Safety Administrations to consider ECDIS as the functional equivalent to nautical charts required by Regulation V, Chapter 19 of the 1974 Convention on the Safety of Life at Sea (SOLAS V/19) (as amended).

Back to top
What is the difference between ECS and ECDIS?

In everyday life, the terms Electronic Chart Display and Information System (ECDIS) and Electronic Chart System (or ECS) have become virtually interchangeable, but from a regulatory perspective ECDIS and ECS are far from equal. A genuine ECDIS is a high quality ECS that meets the requirement of the IMO performance standard and has been tested by an independent type approval authority. Only type approved ECS can legitimately be called ECDIS and only they are considered by the regulatory authorities to meet the requirements of SOLAS.

Why is it important to use official charts?

To ensure compliance with SOLAS requirements.

Can unofficial electronic charts be used for navigation?

Unofficial digital data cannot be used in ECDIS for primary navigation, however it can be used as a supplementary aid to navigation

Who produces and who sells ENCs?

ENCs are produced and authorised by National Hydrographic Authorities such as Hydrographic Offices. ENCs are eventually sold by chart agents and other suppliers in a similar way to paper charts.

What is the difference between a hydrographic chart and a topographic map?

A hydrographic chart (also known as a nautical chart or marine chart) is an essential tool used by mariners to guide them safely from port to port. These charts are specifically designed to meet the requirements of marine navigation by showing the depths of water, the nature of the sea bottom, elevations, configuration and characteristics of the coast, dangers, and aids to navigation. A topographic map focuses on the horizontal and vertical positions and features of land. A topographic map uses contours or comparable symbols to show mountains, valleys, and plains.

What is a Datum?

A datum is any reference system against which measurements may be made. Horizontal datums measure positions on the surface of the earth, while vertical datums are used to measure land elevations and water depths.

Back to top
What is a chart datum?

Chart datum is the reference plane to which depths on a published chart, all tide height predictions and most water level measurements are referred.

What is S-57?

S-57 describes the standard to be used for the exchange of digital hydrographic data between national hydrographic offices, and for the distribution of digital data and products to manufacturers, mariners, and other data users.

The most significant digital product being delivered in the S-57 format is the Electronic Navigational Chart (ENC).

What is S-63?

The publication S-63,IHO Data Protection Scheme describes the recommended standard for the protection of ENC information. It defines security constructs and operating procedures that must be followed to ensure that the data protection scheme is operated correctly and to provide specifications that allow participants to build compliant systems.

Back to top
What is an ECDIS anomaly?

An ECDIS anomaly is an unexpected or unintended behaviour of an ECDIS which may affect the use of the equipment or navigational decisions made by the user. Examples include, but are not limited to:

  • Failure to display a navigational feature correctly
  • Failure to alarm correctly
  • The display of lights with complex characteristics
  • The display of underwater features and isolated dangers.

What does WEND mean?

The Worldwide Electronic Navigational Chart Data Base is an IHO concept, based on the set of WEND principles, designed specifically to ensure a world-wide consistent level of high-quality, updated official ENCs through integrated services that support chart carriage requirements of SOLAS and the requirements of IMO performance standards for ECDIS.

Am I legally required to have nautical charts on board?

While commercial mariners are obligated to have up-to-date navigational charts on board, recreational mariners are not required to do so by law. However, virtually all boating experts agree that paper charts are critical to boating safety — for all mariners.

Where do chart updates come from?

Chart update information is obtained from a variety of sources. Aid to navigation additions, deletions, and changes usually originate from the local coast guard district and are transmitted internally between the aids to navigation unit and the LNM unit in a particular coast guard district.

What is meant by 'print on demand' (POD) charts?

A POD chart is a paper chart that is printed at the time of purchase and contains chart updates until the time of purchase. If the mariner chooses to purchase a POD chart, all updates that have been published in the year between the new edition date and the purchase date have already been applied.

Back to top