Frequently Asked Questions
Page 1
What are IMO requirements for the carriage of nautical charts?
The 1974 International Convention for the Safety of Life at Sea (SOLAS 1974), subsequently amended in 2000 and 2002, specifies the requirements for the navigational equipment to be used onboard ships entitled to fly the flag of a party to the convention. This Convention was adopted by the International Maritime Organisation (IMO), the United Nations Organisation that is concerned with maritime transportation. IMO member states are obliged to adopt IMO rules and regulations into their national legislation.
However, only when the convention text has been incorporated into national legislation does it take effect for the individual ships registered in that country. This process of incorporation into national legislation may vary from a few months to several years. The country in which a ship is registered and hence which flag it is flying is known as the Flag State. It is the national maritime administration representing the Flag State, which controls the adherence to the SOLAS carriage requirements (Flag State control).
The national maritime administration is also responsible for Port State control. Ships arriving at a port may be subject to Port State control by local officials (Port State Control Officers - PSCOs) based on Flag State regulations and international agreements. Port states cooperate within regions to apply consistent standards, for example the European nations and Canada cooperate under the umbrella of the Paris Memorandum of Understanding (Paris MOU).
The requirements for carriage of nautical charts are laid down in
SOLAS Chapter V.
The relevant regulations:
IMO SOLAS V/2 (defines the nautical chart)
- 2.2 Nautical chart or nautical publication is a special-purpose map or book, or a specially compiled database from which such a map or book is derived, that is issued officially by or on the authority of a Government, authorized Hydrographic Office or other relevant government institution and is designed to meet the requirements of marine navigation. The nautical charts and nautical publications referred to in regulation V/2 are commonly referred to as “official charts and publications”.
IMO SOLAS V/19 (specifies the equipment to be carried on different types of ships)
- 2.1 All ships irrespective of size shall have:
- 2.1.4 nautical charts and nautical publications to plan and display the ship’s route for the intended voyage and to plot and monitor positions throughout the voyage; an Electronic Chart Display and Information System (ECDIS) may be accepted as meeting the chart carriage requirements of this subparagraph.
- 2.1.5 back-up arrangements to meet the functional requirements of subparagraph 2.1.4, if this function is partly or fully fulfilled by electronic means.
IMO SOLAS V/27 (specifies the requirement to keep charts and publications up to date)
- Nautical charts and nautical publications, such as sailing directions, lists of lights, notices to mariners, tide tables and all other nautical publications necessary for the intended voyage, shall be adequate and up to date.
- Most vessels still satisfy carriage requirements for charts and publications by the use of paper products, however amendments to SOLAS regulations that came into force in July 2002 allow these carriage requirements to be satisfied solely by electronic means so long as a suitable back up is provided.
- The three regulations referred to above show that the carriage requirement for charts and publications can be fulfilled by: Carriage of official and up to date paper charts, or carriage of a type-approved ECDIS (in accordance with the requirements of the IMO ECDIS Performance Standards – i.e. using up to date Electronic Navigational Charts (ENC) supplemented by an appropriate back up arrangement).
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What kinds of electronic charts are available?
There are two types of electronic chart – raster and vector. A raster chart is a scanned and passive image of a paper chart, whereas a vector chart corresponds to a digital analysis by object (points, lines, areas etc.).
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What are official charts?
Charts issued by or on the authority of a Government, authorized Hydrographic Office or other relevant government institutions are official and may be used to fulfil carriage requirements (provided they are kept up to date).
All other nautical charts are by definition not official and are often referred to as private charts. These charts are not accepted as the basis for navigation under the SOLAS convention.
There are two kinds of official digital charts commonly available; Electronic Navigational Charts (ENC) and Raster Navigational Charts (RNC).
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What is an ENC?
ENC stands for “Electronic Navigational Chart”. The term was originally introduced for digital chart data complying with the IHO chart data transfer standard S-57. By IMO definition ENCs can only be produced by or on the authority of a government, authorised Hydrographic Office or other relevant government institution.
Any other vector data is unofficial and does not meet carriage requirements. ENC content is based on source data or official charts of the responsible Hydrographic Office and are referred to World Geodetic System 1984 Datum (WGS84). ENCs are regularly updated with official update information distributed digitally.
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How do I recognise an ENC?
Only authorized distributors sell ENCs in ENC services which include the delivery of update information.
ECDIS distinguishes an ENC from unofficial data. When unofficial data is used, mariners must navigate by means of an official, up to date, paper chart.
If unofficial data is shown on the ECDIS display, its boundary is to be identified by a special line style. This boundary is visualized as a “one-sided” RED line with the diagonal stroke on the unofficial side of the line.
Further the mariner can use an ECDIS function to interrogate the chart display to obtain the chart details like information on originator, edition number and status of updating.
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How works ENCs distribution?
A majority of all ENCs are only made available to the end-users in a protected form compliant with the IHO S-63 Data Protection scheme. The standard maintains the integrity in all transactions between the service provider and the end-user. The protection scheme enables the end user systems to check the authenticity of the supplied information.
The end-user will require decryption keys to access and view the ENCs. The required decryption keys are distributed to the end-users as ‘Chart Permits’ by the service provider.
The end-user will occasionally receive new ‘Chart Permits’ on floppy disk or by E-mail from their service provider when their ENC subscription is renewed or there are changes to the ENC chart outfit. The updated ‘Chart Permits’ must be imported into the chart system to enable it to automatically process new ENC deliveries and updates. Usually the latest files containing the ‘Chart Permits’ have to be used.
If the ‘Chart Permits’ are sent by E-mail, the attachments labelled: ‘permit.txt’ and ‘enc.pmt’ should be copied to one floppy disk as ‘permit.txt’ and ‘enc.pmt’. Then the floppy disk has to be used for activation of the ENCs. The relevant ENCs are on the ENCs Base CDs & the latest ENCs Update CD. It has to be taken into account that some cells might be new editions and available from a newer ENCs Update CD and can only be installed or updated if this arrives the vessel.
A few nations distribute their ENCs without using encryption; all ECDIS systems are able to access and display these ENCs without ‘Chart Permits’.
Usually the ENCs are provided on CDs. If a new set of ENCs Base CDs was delivered, that CDs will replace all previous Base and Update CDs which then can be disposed of. New update CDs delivered in future will be based on the new Base CDs. If a collection of Update CDs arrive the vessel, always only the latest one needs to be applied.
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Are there other ways that ENCs can be distributed?
The International Hydrographic Organisation has approved the distribution of ENCs in the internal format used by the individual ECDIS manufacturer. The generic name of this format is SENC – System-ENC. Depending on the make of ECDIS this can increase the speed of loading of ENC-data. The IHO requires service providers using this method of SENC-distribution to gain the agreement of the Hydrographic Offices supplying the ENCs and to use type approved software to ensure that the integrity of the SENC data is maintained.
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What is an RNC?
RNC means “Raster Navigational Chart”. RNCs are digital raster copies of official paper charts conforming to IHO Product Specifications RNC (S-61). By definition RNCs can only be issued by, or on the authority of, a national Hydrographic Office. RNCs are regularly updated with official update information distributed digitally. Because of their nature, RNCs when used in ECDIS do not provide the same level of functionality that is provided by ENCs.
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How works RNCs (ARCS) distribution?
ARCS Charts are distributed on 11 ARCS Area CDs. If a new ARCS Area CD is delivered the charts of this CD must always be imported before installing the updates. However, this applies only provided that older versions of charts which are on the CD are stored in your system. In that case please install these charts anew from the CD Rom. The new ARCS Area CD substitutes the old Area CD which then can be disposed of. New updates delivered in future will be based on the new ARCS Area CD. If a collection of Update CDs arrive the vessel, always only the latest one needs to be applied.
If the delivery includes floppy disks with new chart permits these new chart permits must always be imported into the ECDIS before installing a new Area or Base CD, or applying an update.
If the ‘Chart Permits’ are sent by E-mail, the attachments labelled: ‘gb.lcn’ and ‘gb.ncp’ should be copied to one floppy disk as ‘gb.lcn’ and ‘gb.ncp’. Then the floppy disk has to be used for activation of the charts. The relevant charts are on the ARCS Area CDs & the latest ARCS Update CD.
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How are ENCs and RNCs kept up to date?
In order to meet carriage requirements, official charts must be kept corrected by Notices to Mariners issued by Hydrographic Offices. ENCs and RNCs are kept up to date by applying regular, for example weekly, update information to the chart data via a data file. The update file may be transferred by wireless transmission, or by a suitable media e.g. CD. The actual updating is applied automatically by the ECDIS to its chart database. Another standard function of ECDIS is the capability of updating the ENC manually which may be used if the digital update is not available.
At present most ENC and RNC updates are supplied to ships on CD but ‘remote updating’ using satellite (or, when in port, shore based) telecommunications is becoming more and more common. A number of ENC service providers already have updating services using e-mail and web and other means; details may be obtained from ENC distributors.
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Is it possible to check that all updates have been applied to the ENC?
Updates to ENCs are sequential, and the sequence is unique to each ENC. During the updating process ECDIS always checks that all updates in the sequence have been applied. If an update is missing then the ECDIS will indicate this; it is not possible to load later updates until the missing update is applied.
The ECDIS maintains a list of updates applied and the date of application. This list can be used to check the update status of the ENCs loaded. Should all available ENCs show the same date for the latest update, it is likely that they have not been updated regularly, and the distributor should be contacted for verification. Furthermore it is possible to use traditional sources of information, such as Notices to Mariners, to verify updates.
Port State Control officers may use the ECDIS listing to ensure that ENCs are being kept up to date in accordance with SOLAS V Regulation 27.
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What is an ECDIS?
An electronic chart display system is a general term for all electronic equipment that is capable of displaying a vessel’s position on a chart image on a screen. There are two classes of electronic chart display systems. The first is an ECDIS (Electronic Chart Display and Information System), which can meet IMO/SOLAS chart carriage requirements. The second is an ECS (Electronic Chart System), which can be used to assist navigation, but does not meet IMO/SOLAS chart carriage requirements.
ECDIS equipment is specified in the IMO ECDIS Performance Standards as follows:
Electronic Chart Display and Information System (ECDIS) means a navigation information system which, with adequate back up arrangements, can be accepted as complying with the up-to-date chart required by regulation V/19 & V/27 of the 1974 SOLAS Convention. Where the term ECDIS is used in this document, this is to be understood as those navigational electronic chart systems, which have been tested, approved and certified as compliant with the IMO ECDIS Performance Standards and other relevant IMO Performance Standards and thus is compliant with SOLAS ECDIS requirements.
ECDIS is a ship borne navigational device and as such it is the responsibility of IMO. It must support the whole range of navigational functions that make use of the characteristics of the chart data and their specific presentation.
Within the ECDIS, the ENC database stores the chart information in the form of geographic objects represented by point, line and area shapes, carrying individual attributes, which make any of these objects unique. Appropriate mechanisms are built into the system to query the data, and then to use the obtained information to perform certain navigational functions (e.g. the anti-grounding surveillance).
The presentation of ENCs on the screen is specified in another IHO standard, the “Colours and Symbols Specifications for ECDIS IHO S-52”, i.e. in its Appendix 2, called ”ECDIS Presentation Library”. This style of presentation is mandatory.
The use of ENCs in a tested, approved and certified ECDIS and with appropriate back up arrangements, is the only paperless chart option for vessel navigation.
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Is there a mandatory requirement to carry ECDIS?
In December 2006 the Marine Safety Committee (MSC) of IMO agreed amendments to the High Speed Craft (HSC) regulations requiring all HSC craft built after 2008 to be fitted with ECDIS and existing HSC to be retrofitted by 2010.
At the same meeting MSC also accepted the findings of a Formal Safety Assessment (FSA) on ECDIS presented by Norway and other nations showing the positive benefit of fitting ECDIS. As a result of this study MSC has instructed the NAV sub-committee to discuss the extension of mandatory carriage of ECDIS to other classes of vessel and to report back to them in 2008.
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What is an adequate independent back up arrangement?
Only a type approved ECDIS operating with up to date ENCs and with appropriate back up may be used to replace all paper charts on a vessel. Where ENCs are not yet available, IMO regulations allow Flag States to authorise the use of RNCs (together with an appropriate folio of paper charts) - see below. Note that in all other cases the vessel must carry all paper charts necessary for its intended voyage.
The IMO Performance Standards therefore require that the "overall system" include both a primary ECDIS and an
adequate independent back up arrangement that provides an independent facilities enabling a safe take over of the ECDIS functions in order to ensure that a system failure does not result in a critical situation and a means to provide for safe navigation for the remaining part of the voyage in case of ECDIS failure.
There are two commonly accepted options: A second ECDIS, connected to an independent power supply and a separate GPS position input or an appropriate up to date folio of official paper charts for the intended voyage.
Some Flag States may permit other options (e.g. radar-based systems such as ”Chart-Radar”). Ship owners should consult their national maritime administration for specific advice.
At the request of IMO the IHO is currently seeking information from their member states on which paper charts covering their territorial waters would be appropriate to serve as a back up to ECDIS. IHO will compile this information and present it on its web site in the form of a catalogue.
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What to do in areas without ENC coverage?
In 1998 the IMO recognised that it would take some years to complete the world’s coverage of ENCs. As a consequence IMO ECDIS Performance Standards were amended adding a new optional mode of operation of ECDIS, the Raster Chart Display System (RCDS) mode. In this mode RNCs can be used in ECDIS to meet SOLAS carriage requirements for nautical charts. However, this is only allowed if approved by the Flag State. The intention of those changes was to allow the ECDIS to operate as far as possible on official chart data; ENCs where they were available and RNCs to fill in the gaps.
IMO took note of the limitations of RNCs as compared to ENCs (see IMO SN Circular 207 at Annex), and the revised ECDIS Performance Standards require that the ECDIS must be used together with “an appropriate folio of up to date paper charts” for the areas where RCDS mode is employed. The intention was to allow the number of paper charts carried by a vessel to be reduced where RCDS mode was employed, but only to a level compatible with safe navigation. No definition of an “appropriate folio” was provided by IMO and consequently different Flag States developed individual interpretations.
As there is no common interpretation of the term “appropriate” ship owners should consult their Flag State as to whether RCDS mode is allowed and under what conditions.
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How is the acceptance of ECDIS by Port State control?
Ships arriving at a port may be subject to Port State control by local officials based on Flag State regulations and international agreements. Nations have formed a number of regional groups to ensure consistent application of Port State controls.
In Europe the Port State control acts on the regulations set out in the Paris Memorandum of Understanding. Its ECDIS guidelines explain how a PSCO should assess whether a ship is using electronic charts in accordance with SOLAS requirements.
Checks may include whether:
- The ship has documentation indicating that the system complies with IMO Performance Standards for ECDIS. In the absence of such documentation, the PSCO should seek confirmation from the Flag State that the system does meet the statutory requirements;
- The system is being used for primary navigation. It should be established if ECDIS is used in the ENC mode or RCDS mode or in both modes;
- There are written procedures onboard the vessel for using ECDIS;
- The master and watch-keeping officers are able to produce appropriate documentation that generic and type-specific ECDIS familiarisation has been undertaken;
- The charts used for the intended voyage are the latest official editions;
- The charts in use are updated
- There are approved back up arrangements available to ensure a safe transfer of the ECDIS functions in the event of ECDIS failure and to provide safe navigation for the remaining part of the voyage.
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Is there a need for ECDIS training?
Unlike the paper chart, ECDIS is a highly sophisticated system which, besides the navigational functions, includes components of a complex, computer-based information system. In total, the system includes hardware, operating system, ECDIS software (kernel and user interface), sensor input interfacing, electronic chart data, rules for presentation and display, status and parameters of alarms and indications, etc. All these items are accessed through an appropriate human-machine interface. As such, care must be taken when navigating with ECDIS to avoid false operation, misinterpretation, malfunction or even worse and over-reliance on this highly-automated navigation system.
As with any type of shipboard navigation equipment, it can only be as good as those who use it and what it is being used for. In the case of ECDIS and electronic charts, if the mariner is well trained then the system provides the information flow that the mariner needs to make good decisions and therefore contributes significantly to safe and efficient navigation.
Stated another way, an electronic chart system is another tool to enable mariners to perform their job better. However, just having some “knowledge” about “functions” and “operational controls” is insufficient to maximise the benefits of ECDIS; proper training is absolutely necessary.
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What are the requirements for ECDIS training?
ECDIS and other electronic charting systems have become increasingly important to ship navigation and are already widely used either as a primary navigation tool or as an aid to navigation. The systems are increasingly complex, and require adequate and appropriate training in order to be operated correctly and safely. Without proper training, these systems will not be used to their full potential and could under some circumstances increase the hazard to navigation. The STCW (Standards of Training, Certification and Watch-keeping) and ISM (International Safety Management) codes put the responsibility firmly on the shipowner to ensure that mariners on their vessels are competent to carry out the duties they are expected to perform. If a ship is fitted with ECDIS, the shipowner has a duty to ensure that users of such a system are properly trained in the operation and use of electronic charts and are familiar with the shipboard equipment before using it operationally at sea.
There is no specific regulation or reference to ECDIS systems in the STCW Convention. However, since ECDIS systems are related to electronic charts, references about them are considered to be included in the material covered by the word “chart”:
- To encourage effective ECDIS education, the IMO approved a standardised model course for ECDIS training on the operational use of ECDIS in 1999 (IMO course 1.27). This course is offered by approved training institutions and maritime academies. Maritime administrations can provide information on approved institutions. Some Flag States have developed their own training courses in ECDIS in order to be able to recognise the training certificates.
- Type specific ECDIS training is provided by equipment manufacturers.
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What are the operational considerations when using ECDIS?
Navigating with ECDIS is fundamentally different from navigating with paper charts. Important bridge work-processes are significantly affected, in particular, voyage planning and voyage execution task. These require careful analysis and consideration:
Voyage Planning
ECDIS provides a number of additional planning functions and features such as safety contours, alarms, click-and-drop facilities for waypoints and markers, etc. Whilst in many ways ECDIS makes voyage planning easier it is still possible to make errors, however these are likely to be of a different type to those encountered when using paper charts.
Even though ENC coverage is increasing rapidly, many vessels will, to some degree, have to operate a dual – or even triple – system with ENCs paper and raster charts. Planning and validation of the route has therefore to consider issues such as which chart types are available for the various segments of the voyage. The format of the voyage plan is likely to differ from the traditional alphanumeric lists of waypoints used with paper charts and should include information on the usability of connected electronic navigational devices such as GPS and AIS and their actual alarm settings.
It is essential to make use of the in-built automatic check functions provided by ECDIS when validating and approving the voyage plan. Thought also needs to be given to ensuring that a backup to the voyage plan on the ECDIS is available in case of equipment failure of the ECDIS itself or the connected sensors.
It is important that there is good communication of the voyage plan to all bridge officers so that they are prepared for the intended voyage. This should include information on equipment status and backup procedures.
Voyage Execution
At the beginning of the voyage, as well as at any change of watch, the officers should review the voyage plan and agree the selected pre-settings of functions, alarms and indicators to be used on the ECDIS.
Where vessels carry paper charts as well as an ECDIS the role of the ECDIS and the charts should be considered. If the ECDIS is used for real time navigation, the statutory requirements regarding monitoring of the progress of the voyage and marking of positions will need to be considered:
- are positions marked in paper charts solely for record keeping purposes?
- what steps are taken to ensure that intended tracks marked on the paper charts correspond with the ECDIS information?
- have the bridge procedures set in place by the shipping company been adapted for the use of ECDIS and are all persons concerned with the navigation familiar with these adaptations.
Over reliance on ECDIS
There is a tendency to put too much trust in computer based systems and believe whatever is on the display. It is essential that officers remember to cross check the information displayed by all other means available; especially by looking out the window and watching the radar! Bridge-procedures must be adapted appropriately and ENC training must be carried out to alleviate these concerns.
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What is an ECS?
ECS is a navigation information system that electronically displays vessel position and relevant nautical chart data and information from an ECS Database on a display screen, but does not meet all the IMO requirements for ECDIS and is not intended to satisfy the SOLAS Chapter V requirements to carry a navigational chart.
All systems, which are not tested to show compliance with the ECDIS Performance Standards, can be generically designated as ”Electronic Chart Systems” (ECS). An ECS may be able to use either ENCs, RNCs or other chart data produced privately and could have functionality similar to ECDIS.
Where the vessel operates with ECS, the paper chart remains the official basis for navigation onboard. The vessel must retain and use a full folio of up to date paper charts onboard, regardless of the type of electronic charts used. The STCW and ISM codes put the responsibility firmly on the shipowner to ensure that mariners on their vessels are competent to carry out the duties they are expected to perform.
If a ship has ECS fitted, the shipowner has a duty to ensure that users of such a system are properly trained in the operation and use of electronic charts, are aware of the limitations compared to ECDIS and are familiar with the shipboard equipment before using it operationally at sea.
