ECDIS Course Notes - 2012

(A unit of Jyothi Educational Society)

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(IMO MODEL COURSE 1.27 Revised 2010)

C O N T E N T S

Page No.

1. Glossary of Terms related to ECDIS 1

2. Brief History of ECDIS 3

3. What is ECDIS and what can it do? 7

4. A Practical Update To Electronic Charting 22

5. Integrating ECDIS With Other Electronic Systems 36

6. ECDIS Back-Up Requirement 38

7. Maintaining And Updating ECDIS 41

8. ECDIS Advantages & Limitations 44

9. Raster vs. Vector Electronic Charts 51

10. Passage Planning with ECDIS 56

11. ECDIS implementation 74

12. ECDIS Case Study 77

13. IMO performance Standards - Res. A817(19) 79

14. Technical Details of Electronic Chart 98

Only for use by Students of IMC

Glossary of Terms related to ECDIS

ARCS Admiralty Raster Chart Service - the UK HO proprietary RNC.

BSB Raster Data format used by USA and Canada

DNC Digital Nautical Chart by NIMA -USA DIGEST

Digital Geographic Information Standards (NATO standard that WECDIS can read)

ECDIS

Electronic Chart Display and Information System The performance standard for ECDIS approved by the IMO assembly in November 1995. The standards are defined in documents of the IHO and IEC: IHO Special Publication S-52 Provisional Specifications for Chart Content and Display of ECDIS; IHO Special Publication S-57 IHO Digital Data Transfer Standard IEC 61174 ECDIS Performance Standards.

ECDIS-N Electronic Chart Display information system Navy (US)

ECS Electronic Chart System - a chart system which does not meet the requirements of SOLAS V/20 and is not defined by official standards.

ENC Electronic Nautical Chart

EPFS Electronic Position Fixing System GPS, Loran, Decca etc

HCRF Hydrographic Chart Raster Format. This is the format developed by UK HO and used (at September 1997) by the UK HO for its Admiralty Raster Chart Service (ARCS) and the Australian HO for its Seafarer Chart Service. Other HOs are also expected to adopt HCRF.

IC-ENC International Centre for ENCsRENC operated by UK Hydrographic Office

IEC International Electro-technical Commission

IHO International Hydrographic Organisation

IMO International Maritime Organisation

ISM International Safety Management Code

ISO International Organization for Standardization

NIMA National Imagery and Mapping Agency

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NMEA

National Marine Electronics Association NMEA 0183 version 2.01 is the standard which is defined to permit the ready data communication between electronic marine instruments, navigation equipment and communications equipment when interconnected via an appropriate system.

Primar Stavanger RENC operated by Norwegian Hydrographic Office

RCDS

Raster Chart Display System (RCDS) means a navigation information system which can be accepted as complying with the paper version of the up-to-date chart required by regulation V/20 of the SOLAS Convention, by displaying RNCs, with position information from navigation sensors to assist the mariner in route planning and route monitoring, and if required display additional navigation-related information. A draft performance standard for RCDS is being considered by IMO.

RENC Regional ENC Coordination Centre

RNC Raster Navigational Chart means a facsimile of a paper chart. Both the paper chart and the RNC are originated by, or distributed on the authority of, a government authorised hydrographic office.

S-52 IHOs special publication No. 52. IHO Colour and Symbols Specifications for ECDIS

S-57 IHOs special publication No. 57. IHO Transfer Standard for Digital Hydrographic Data

S-61 IHOs special publication No. 61. IHO Product Specification for Raster Navigational Charts

S-63 IHOs Special publication No. 63. IHO Data Protection Scheme

SOLAS The International Convention for the Safety of Life at Sea. Chapter V - Safety of Navigation, Regulation 20

SENC System Electronic Navigational Chart (ENC transformed by ECDIS)

VPF Vector Product Format

WEND World ENC Database

WGS84 World Geodetic System 1984

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Brief History of ECDIS The International Hydrographic Organisation (IHO) in the 80s identified that emerging computer technology and position fixing systems could provide a digital representation of the paper chart on a computer screen, along with real-time positioning and interfaces to radar and other navigation sensors. The IHO formed working groups to define the standards for data encoding and digital chart presentation. From this early work, the Electronic Chart Display and Information System (ECDIS) evolved. Consistency and legal liability is a major issue for international navigational charts. For this reason, the IHO developed two standards. The first standard, S-57, describes the data model, object and attribute definitions for charted objects, encoding guidelines, product specifications and data structure of the Electronic Navigation Chart (ENC). The second standard, S-52, describes the presentation of the colours as well as chart and navigation symbols for ECDIS. The IHO also works closely with the International Maritime Organisation (IMO), to develop operational performance specifications and a rigorous type-approval test regime for ECDIS manufacturers. For a system to be certified as being ECDIS- compliant, it must be type approved by an independent authority. The type approval process ensures that the ECDIS functions in accordance to the specified tests developed by the IMO, the IHO and other international bodies. For large commercial shipping, the IMO and its national member countries have mandated that vessels must carry ECDIS for primary navigation in certain national waters. A contributing factor to the slow emergence of ECDIS, has been the lack of S-57 ENC data produced by the national Hydrographic Offices (HOs). The availability of ENC data is gradually increasing, but most HOs still lack adequate coverage of their waters. During the 1990s, several HOs with large areas of responsibility (i.e. Australia, UK, USA) identified that production of ENCs would be a lengthy process and thereby developed a Raster Navigation Chart (RNC) product that could quickly fill the official digital data gap and provide users with the foresight of what was to come with ECDIS. With the availability of ECDIS technology, several HOs have adopted a position whereby a RNC, when used on an ECDIS, will have legal equivalency to the paper chart. The lengthy time required to develop these standards provided opportunities for private companies to develop like-systems using proprietary file formats and data presentation,

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usually operating on a PC environment. These systems, whilst providing much of the navigational functionality of ECDIS, they did not generally use official data or provide the necessary backup facility. These systems are called Electronic Chart Systems (ECS). Hence, ECS do not meet the legal requirements of the IMO for safe navigation. When using ECS, the user should have a copy of the official paper chart as a backup. Feedback from those involved in the use of charts and electronic charting systems including manufacturers, distributors, users, ship owners, regulatory authorities, pilots, harbour authorities and others indicates a requirement to provide guidance on the regulations and the status of equipment that is available in the market today. In particular the differences between the various types of equipment and the differences between the various types of chart data offered to the users are unclear with respect to the regulations in place. International regulation has had difficulty in keeping pace with the growing development and use of ECDIS, while realising the need for mandatory training.In response to the increasing development and use of ECDIS, the International Maritime Organisation (IMO) has made amendments to the International Convention for the Safety of Life at Sea Convention (SOLAS) and the Standards of Training, Certification and Watchkeeping (STCW) code to incorporate new requirements for the mandatory carriage of ECDIS under SOLAS (for ships engaged on international voyages only) and, as a complement, mandatory ECDIS training as required under the Manila amendments to the STCW code. The new amendments to SOLAS Chapter V (Safety of Navigation) Regulation 19 Carriage Requirements for Shipborne Navigational Systems and Equipment require mandatory carriage of ECDIS for certain new ships built on or after 1 July 2012 and a subsequent timeline plan for retrofitting ECDIS to existing applicable ships. The Manila amendments to the STCW code have also been updated to complement the new ECDIS carriage requirements and include mandatory training for ships operating with ECDIS. The Manila amendments are due to enter into force on 1 January 2012. Manila amendments to the STCW Code 2010 The understanding of the STCW Manila Amendments has caused confusion within the industry, particularly with respect to the transitional provisions for deck officers who already possess (or are due to revalidate their) watch-keeping certification and who have not undergone ECDIS training. It is of course left to flag states to interpret the

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code and clearly define what training and certification requirements they will specifically impose. However, a general interpretation of the transitional provisions of the Manila Amendments is as follows (subject to flag state interpretation): after 1 January 2012, ECDIS training will be a requirement under the revised STCW Code parties (flag states) may continue to issue, recognise and endorse certificates in accordance with the 1995 version of the STCW Convention until 2017. But this is only permitted in respect of seafarers who, as of 1 July 2013, have already begun their seagoing service or are already involved in training activities as required by the STCW Convention (it is understood that this is to give the colleges and training providers 18 months to comply with the new regulations) paragraph 2 refers to revalidation. Certificates of competency could be revalidated up to 1 January 2017 under transitional provisions without ECDIS training, subject to flag state requirements. However, certain flag states have issued requirements that if a ship is using ECDIS as a primary means of navigation, then officers must have generic and type specific training/certification now. Therefore, certificates of competencies that have been revalidated up to 1 January 2017 without ECDIS training may not be valid for navigation onboard ships using ECDIS as a primary means of navigation. This will depend on the relevant flag states interpretation However, certain flag states such as the UK, Bermuda, Australia and the Marshall Islands already require deck officers using ECDIS as a primary means of navigation to undergo generic ECDIS training (conforming to IMO Model Course 1.27) as well as an ECDIS type/ model specific course. The issue of ECDIS type specific courses has become a topic of discussion and debate within the maritime industry as concern has been raised over the cost and time needed to train officers who are already ECDIS generic trained but lack the type/model specific knowledge. Companies that have different models of ECDIS onboard their ships are being encouraged to review their ECDIS training procedures through a gap analysis with a focus on evaluating what training requirements may be needed by their ships flag state. The requirements therefore can be complex and costly.

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The International Safety Management (ISM) Code is at the forefront of compliance with new ECDIS requirements. The ISM Code requires companies to ensure each ship has properly maintained equipment with qualified and certificated seafarers in accordance with national and international legislative requirements. This includes SOLAS and STCW. The legislative requirements for ECDIS training are daunting. The sheer numbers and scale of the training required is going to test many companies ability to complete the training in time and interpret the varying flag states requirements. Companies need to plan for this immediately if not already started. Many companies already have ECDIS fitted onboard their ships and yet do not insist that the watch-keepers be trained in its use, the argument being that ECDIS is not being used as a primary means of navigation and is not a mandatory requirement. This is a short-sighted approach and, in any event, ECDIS training will become a requirement under the revised STCW code when the Manila amendments enter into force on 1 January 2012. However flag states will interpret the exact training requirements for ECDIS and are likely to incorporate some kind of phasing-in timeline or programme for training for existing officers as may be allowed under Regulation I/15 Transitional provisions of the Manila amendments. The transitional provisions of the Manila Amendments have caused confusion within the maritime industry, in particular the requirements and timeline for existing navigational officers to be ECDIS trained and certified when operating onboard a ship fitted with ECDIS. The transitional provisions of the Manila amendments allow flag states to continue to renew, revalidate and endorse certificates of competency up to 1 January 2017 without ECDIS training in accordance with the provisions of the Convention which applied immediately prior to 1 January 2012, that is, STCW 1995 requirements. This means that depending on what the ships relevant flag state stipulates, shipowners and operators with existing certificated navigational officers will have a suitable time period to implement an ECDIS training programme prior to 1 January 2017 but must be in line with the specific flag states requirements. If watch-keepers using ECDIS, even as an aid to navigation, are not properly trained in its use or fully understand the functionalities of each specific type of ECDIS unit, the risk of incidents resulting from ECDIS assisted collisions and groundings is likely to increase.

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What is ECDIS and what can it do ?

For some years a new concept has been making its presence felt in shipping circles: ECDIS. Better known under the term electronic nautical chart, all kinds of nautical chart presentations on computers are often called ECDIS, not just by landlubbers but also by seafarers and the equipment suppliers. However, there are standards and specifications that precisely define the nature of an item of equipment that may be designated ECDIS and is intended for professional shipping. What an ECDIS is, what are its component parts, who supplies the chart data, what standards have to be met, who uses ECDIS and what advantages it offers are the questions answered below.

ECDIS in Operation Overview chart What does the abbreviation ECDIS stand for?

E = Electronic C = Chart D = Display and I = Information S = System

The definition of an ECDIS and its use is specified in IMO ECDIS Performance Standards (IMO Resolution A.817 (19) and Resolution MSC.232 (82)): 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

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1974 SOLAS Convention, by displaying selected information from a system electronic navigational chart (SENC) with positional information from navigation sensors to assist the mariner in route planning and route monitoring, and by displaying additional navigation-related information if required. ECDIS is thus more than an "electronic nautical chart". Nautical charts are in fact presented electronically, but in principle all kinds of chart - aviation charts, street maps, railway maps, etc. - could be presented on a computer display using the same methodology. However, we shall restrict ourselves to comments on the electronic nautical charts. ECDIS was initially developed for shipping, and thus the use of both terms as synonyms is entirely justified. On the other hand, electronic chart presentation is only one aspect of ECDIS. ECDIS is also an information system. As an information system, ECDIS enables the user to call up information on the items displayed in addition to the graphics presentation. For instance, a lighthouse. This is marked on the chart by a tower symbol. The system can give further information on this object, e.g. the fact that the tower has horizontal red/white stripes, is a 28 m high steel structure on a masonry base called "Roter Sand", and that it used to be manned but is no longer operational and is now preserved as a monument. The data may make it possible to call up a further text presenting a detailed history of our lighthouse. It may also be possible to view a digitised photo of this object. The amount and quality of the information available on the individual objects depends on how up-to-date, accurate and well maintained the data base is, not on the ECDIS itself. ECDIS stores these various details in a geographic, object oriented data base. Hence ECDIS belongs to the group of Geographic Information Systems (GIS).

Object information in the so called "Pick-report"

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What are the components of ECDIS? For the user, i.e. the navigator, ECDIS is only one item of equipment among many on the bridge of a modern ship. Operating the ECDIS is thus not the main duty of a ship's officer. Rather, the system replaces the conventional chart table and is intended to permit all types of work traditionally connected with the paper nautical chart and to make these activities easier, more precise and faster. These include route planning, entry of observations, instructions and notes, position determination and, last but not least, updating charts with the aid of the Notices to Mariners (NtM). ECDIS represents an item of equipment consisting of

Hardware Software and Data.

The Hardware of the ECDIS - is generally a computer with graphics capability, a high performance PC or a graphics workstation installed in a console linked with other items of ship's equipment. Thus, ECDIS obtains the course from the gyro compass, the rate of turn from the turn indicator, and the ship's speed through water from the log (the ship's "speedometer"). Key features are the links with the position sensors of the ship (Decca, Loran, transit satellite navigation system) and in particular with the GPS (global positioning system, a satellitebased positioning system), supplying via the NMEA interface a constant stream of highly precise position data (NMEA National Marine Electronics Association; NMEA0183 Standard for Interfacing Marine Electronic Devices, data record). Even radar pictures can be superimposed, either as raw data from a rasterscan radar, or as synthetic ARPA (automatic radar plotting aid) radar information. The hardware should be type-approved and comply with the guidelines of International Electrotechnical Commission (IEC 61174.) The Software should be as the IMO Performance Stanadards [Resolution A817(19)] It consists of the user interface (UI) and the so-called ECDIS kernel, the software that makes it possible to read the data and display a chart. This software is also called 'function library'. In addition to the chart picture, the user interface shows buttons and keys for operating the nautical chart.

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The Data Electronic navigational Chart (ENC) There are two different types of electronic charts in use with ECDIS and all navigation officers and marine managers should be aware of their differences and limitations. Electronic Navigational Charts (ENC), commonly referred to as vector charts, are layered with digital information enabling the mariner to electronically interrogate features on the chart such as buoys, navigational marks, traffic separation schemes (TSS) and safety contours with detailed information displayed for the user. The chart database is organized in cells that cover the entire earth's surface without overlapping. The cells store all nautical chart objects as well as objects created only during the operation of the system, such as waypoints and leg lines, notes, positions of own ship and of other vessels, etc. The data in the System Electronic Nautical Chart (SENC) is generated from the original data of the ENC. The ENC has to be kept unaltered in order to be able to reconstruct the SENC data if this is unintentionally damaged or destroyed. In SENC, the chart data is stored a proprietary file format designed by the ECDIS manufacturer for speed and reliability. The S57 data represents a specific kind of attributed vector data. The kind of data (object description with geometry and geographical position) requires an efficient kind of storage. For compactness and speed, vector data is the optimal solution in contrast to the voluminous raster data. ENCs enable the ECDIS to set different types of navigational alarms to act as a warning to the mariner. These warnings are usually visual as well as audible to give a clear indication of any dangers that lay ahead. The navigational alarms can include such hazards as shallow depths, shoals and isolated dangers as well as minimum under-keel clearance (for example, anti-grounding alarm) provided the ships echo sounder has been integrated with the ECDIS, draught details and alarm parameters specified. Early warning alarms of approaching waypoints and alteration of course points, position fixing reminders and changing electronic chart alarms can also be specified within the alarm parameters. ENCs provide the mariner with a clear display of

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the navigational situation without distorting the chart display when reducing the chart scale.ENC must conform to IHO (International Hydrographic Office) S-57 standards. The ENCs must be supplied by or on the authority of a Government or supplied /authorised by a National Hydrographic Office. The Australian Maritime Safety Authority (AMSA) has issued a circular entitled the Carriage and use of Electronic Chart Display and Information System (ECDIS) information sheet, which states:the so-called derived electronic charts produced by commercial producers or suppliers are not recognised under SOLAS Chapter V as meeting the relevant chart carriage requirements. If the unofficial chart data is produced by commercial producers/suppliers, it does not meet IMO/SOLAS standards for chart carriage and can therefore not be relied upon as a primary means of navigation. Only ENCs officially authorised and produced by a National Hydrographic Office conforming to IHO S-57 standard can be considered as fulfilling the chart carriage requirements of SOLAS Chapter V. If an IMO-compliant ECDIS is using unofficial chart data for navigation, the ECDIS is classified as an electronic chart system or ECS. ENCs are named and identified by an eight-character code (for example GB 600100). The first two characters identify the producer (for example GB = Great Britain, FR = France). To identify a particular code and its producer, a complete list of producer codes can be found in the IHO standard S-62. Some ECDIS systems offer additional databases for tidal information, including predictions and automatic calculation of high water, low water, tidal heights and streams. However, care should be taken when using such information as not all data provided by ECDIS manufacturers is officially authorised or approved by flag states.Masters and officers should be aware of the limitations of ENC data, including the dangers of overreliance on ECDIS. ENC data can cause operator error particularly as electronic navigational charts contain digitally layered information. Overreliance on ECDIS when using ENC data may prove dangerous if inadequate training and familiarisation has been given. Unfamiliarity with ENC data and ECDIS functionality may cause operator error. The International Hydrographic Office has issued a circular warning that ECDIS may not display some isolated shoal depths

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when operating in base or standard display mode. As a result, route planning and monitoring alarms may not always be activated when approaching such dangers and may result in groundings. Mariners must ensure their ECDIS display has been set-up properly to the circumstances and conditions so that it includes all information necessary for safe navigation. ECDIS display modes that are set-up in base display mode may remove


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vital information. The ECDIS display should be set-up appropriate to the environment the ship is operating in. This may differ between navigational environments such as pilotage, coastal, deep sea and anchoring situations as layers of data may need to be added or removed depending on the situation. Raster Navigational Charts (RNC) - are scanned geo-referenced images of official paper charts. RNCs must conform to IHO product specifications S-61 and be officially authorised and produced by or under the authority of a National Hydrographic Office. RNCs do not offer any of the added functionalities or features of ENCs as they are only digitally scanned copies of paper charts. The chart datum used for GPS (WGS 84) may differ to the chart datum used in certain raster navigational charts when operating in Raster Chart Display System (RCDS) mode and can offset Global Positioning System (GPS) positions if a correction has not been applied (datum offset correction) to the GPS unit.


Paper charts will often note a GPS correction under the heading Satellite Derived Positions on the chart itself if it has not been WGS 84 surveyed. This correction must be applied to the position fixing system (for example GPS) to avoid inaccurate positions. Attention is drawn to the IMO Safety of Navigation circulars, particularly SN/Circ. 213 Guidance on chart datums and the accuracy of positions on charts. Some RNCs that are not WGS84 surveyed may apply the datum correction automatically by the ECDIS. However, not all RNCs contain the data file to enable a shift of WGS-84 as this is not always possible. Therefore it may be necessary to manually change the datum at the GPS receiver (this would be in line for ensuring that plotting such received positions onto the paper chart while in RCDS mode will therefore be the same and avoid confusion). Care should also be taken by the navigator when using RNCs that are still using fathoms for depth measurement particularly if the ECDIS is configured to metres. Care should be taken by navigation officers to check the chart datum of the chart with that of the position fixing system to ensure they are compatible and the positions being plotted are as accurate as possible. RNCs do not offer the operator the same options as an ENC to add or remove irrelevant chart features that are not relevant or suit a particular navigational circumstance as there is no digital chart layering system. The ability to scan ahead when determining upcoming alterations of course, navigational hazards and landmarks may prove tiresome as RNCs may need to be changed.In most circumstances, the user is also unable to interrogate any of the chart features or reveal further information. Raster chart data will not trigger automatic alarms (for example, anti-grounding). Some user-defined alarms can be generated by operating in RCDS mode provided the mariner inserts the necessary information. Under IMO performance standards, the following alarms and indications are required for an ECDIS operating in RCDS mode:

ECDIS operating in raster mode deviation from route position system failure approach to critical point different geodetic datum malfunction of RCDS mode large-scale RNC available for ships position

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Changing the display orientation from North-Up may affect the readability of the chart. Chart symbols in RCDS mode are designed to be viewed in a North-Up orientation, like a paper chart. RNC chart projections can differ between each chart which can affect the detail and amount of navigational information (for example depths, contours) displayed on the ECDIS. Increasing and decreasing the chart size may distort the readability of the chart. RNC data should always be viewed at the true scale of the paper chart to avoid distortion. RNC data highlighting existing features may differ in colour in certain circumstances to show similar chart information and may also include changes in colours used in hours of daylight and darkness. IMO safety of navigation circular SN207 (1999) Differences between RCDS and ECDIS should be consulted for further information. Who compiles/ supplies the chart data for the electronic nautical chart? The publishers of official data for the electronic nautical charts are the national Hydrographic Offices (HOs) of the maritime nations, as is the case for the paper nautical charts. In the Federal Republic of Germany this is the Federal Maritime and Hydrographic Agency (German abbreviation: BSH), based in Hamburg. Hydrographic Offices can be themselves the producers of the data or they commission private companies to produce data and then verify and certify the results. Non-certified data from private suppliers is not permitted for navigational purposes and is allowed only to be used as a supplement to the official nautical charts (paper or electronic). At present, data supply is still a weak point of ECDIS. The hydrographic services are public authorities that now have to switch from production of paper nautical charts to digital ECDIS data. Owing to the current shortage of public funds and the necessary restructuring programmes, only a small fraction of the earth's surface has been covered digitally with official data up to now. Since other services, such as regular updating, nautical publications, etc., have to be converted to a digital format, it will be some time before an up-to-date digital global database is available for navigational purposes.

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Why, you may ask, are the existing paper nautical charts not digitised in order to overcome this bottleneck? As shown below, scanned paper charts cannot serve as alternatives to the authentic ECDIS data. Nevertheless, raster data is provided by official sources and fills the gaps in ECDIS data. As publisher of the only set of paper nautical charts with worldwide coverage, the British Admiralty (BA) has decided to scan all paper charts and publish them as Admiralty raster chart system (ARCS) with updates (via bitmap patches). As long as there is no complete coverage with ECDIS data, ARCS data will serve as a practical alternative. Each ECDIS will also be able to read and display this raster data, although such a functionality is not included in the ECDIS specification.

ARCS Raster chart

The scanned paper charts, however, provide no real alternative to ECDIS data. Raster data consists of purely pixel pictures. These pixels on the screen are none other than a blob of colour on the screen. The user has to interpret them in order to recognize them as belonging to an object. In contrast, ECDIS data is vector data. That means that the geometry of the chart objects is described by polygon lines that are not brought on to the screen with colour and patterns until the system is running.


Pixels of vector data can tell the user what object they belong to. The user can move the cursor to any spot on the chart and with a single click open a window displaying the information on the selected point, e.g. depth of 510 m. This information makes the life easier for the user of the chart, and also enables the anti-grounding (AG) and collision avoidance (CA) functions of the computer. ECDIS computer continually and automatically checks the data to establish whether holding the course will risk collision and/or stranding. If this is the case, the navigator is given a warning (acoustic signal or flashing light). Of course, the data must be up-to-date and correct. What standards have to be complied with? Several international authorities are involved in the standardization of ECDIS. The International Hydrographic Office (IHO) has the responsibility for standardizing the digital chart objects for ECDIS. The IHO has drawn up a data model, an object catalogue and an ENC product specification (PS) as standard for ECDIS data and published these in its Special Publication No. 57 (S57). The object catalogue is what the Chart 1 (INT 1) was for the paper nautical chart: a list of all permitted hydrographic object classes. In fact, Chart 1 is reflected almost entirely in the object catalogue. The S57 publication contains also the format description of the exchange format (also called S57) for digital nautical chart data. In addition, the S57 data should be encapsulated according to the ISO 8211 standard. This guarantees that data from the various national HOs are compatible with one another and can be read by each ECDIS. Finally, it should be pointed out that the S57 data does not contain any information concerning the symbolization, the presentation of the chart on the screen. But how, then, is the colourful picture created on the screen?

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The answer to this question is given by the second IHO standard important to ECDIS, the presentation library (PRESLIB) published in the Special Publication No. 52 (S52). Presentation of the chart is generated on-the-fly in ECDIS upon reading of the chart data, the appropriate symbolization for each object being sought from the presentation library according to its characteristics. Hence the ECDIS supplier must install the presentation library in his unit with the definitions of the symbolization instructions and the colours to be used in an absolute manner irrespective of the colour monitor. This, and colour calibration instructions and techniques that the supplier of an ECDIS has to carry out, guarantees that the ECDIS charts look exactly the same on any unit from any manufacturer. Chart data comes without geographic projection, only with coordinates. ECDIS must then provide also geographic projection for a cartographic presentation. For shipping, it means usually the Mercator or sometimes gnomonic projection. The publications S57 and S52 can be obtained from the International Hydrographic Bureau (IHB) in Monaco. The above describes the standardization of the data side of ECDIS, or, to be precise, of the hydrographic data. There are indeed other chart objects that certainly must be specified in order to make ECDIS an adequate navigational tool. A wide range of "objects" are entered into the chart by the captain and the navigators before and during the voyage of the ship. These include leg lines and waypoints, notes, observations, fixed positions and commands. To ensure that this is also possible with the electronic medium of ECDIS, the International Maritime Organization (IMO) has developed an ECDIS performance standard. This determines how an ECDIS has to work so that it can serve as an adequate replacement for the paper nautical chart in accordance with the International Convention for the Safety of Life at Sea, 1974 (SOLAS 74). IMO has produced a catalogue of user-defined objects which has been published under the title "Mariner's Navigational Objects" (NavObj) as an appendix to S52. The supplier of an ECDIS has to ensure that these objects can be generated, edited and deleted as required.

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Another specification should be observed even if it does not come from an international standards organization but from the classification society Det Norske Veritas (DNV), the Norwegian counterpart of Germanischer Lloyd (GL) as it is important for ECDIS functionality. This is the specification for one-man watch operation at night (Watch-1 specification), which lays down the minimum requirements for bridge equipment and navigation facilities (ECDIS is, first of all, a navigation facility) under these conditions. This watch modus is becoming increasingly significant in view of the need to promote the cost efficiency on modern oceangoing vessels. The hardware of an ECDIS must meet the standards of the IEEE (Institute of Electrical and Electronic Engineers) for such items of equipment. To sum it up, an ECDIS must offer the following characteristics:

Reading ENC data (S57) and transferring it to SENC Presentation of objects and their characteristics according to presentation library

(S52) Antigrounding function Warning of obstructions to shipping Updating Various types of chart work must be possible, eg:

o Entering fixed position o Route planning o Entering notes and observations o Sounding, measuring of distances

An ECDIS device has to meet the aforementioned standards. These are monitored by national shipping authorities and institutions in the Federal Republic of Germany, the GL as a classification society and the BSH. Only an ECDIS that has been officially certified may be used in navigation as an adequate replacement for the paper nautical charts. It goes without saying that in a certified ECDIS only certified "official" data may be used for navigation purposes. There is, however, also the possibility of permitting the use of a system that does not strictly meet all the requirements, the so-called Electronic Chart

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System (ECS), which can be utilized like an ECDIS but may not be employed as the sole item of navigation equipment. 6.What are the advantages of ECDIS and who uses it? An ECDIS satisfying all the abovementioned requirements is not only an adequate replacement for the paper nautical chart but also a system containing all information important for navigation that can be called up at any time and without delay. Today, this information is still scattered about in various publications, and manual search procedures are laborious and time consuming. ECDIS also offers the possibility of automatic antigrounding alarm, which is not possible with any other navigation aid.

ECDIS Display in bright daylight ... ... and during night time In 1989, the "Exxon Valdez" ran aground in Prince William Sound in Alaska as a result of prematurely changing course due to false identification of an island. It leaked oil, causing a major environmental catastrophe.

Had "Exxon Valdez" an ECDIS on the bridge, she could have avoided running aground. With a continually updated display of the position of the ship, the premature change of course would have probably never occurred. Moreover, the ECDIS antiground function would have produced an alarm when the vessel was approaching the shallows, warning the officer on duty of the danger. As an experienced captain once remarked, "With ECDIS, a navigator knows for the first time in the history of seafaring not where his ship was but where it is!"

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A further advantage of ECDIS compared to all other navigation aids is the individual adaptation of the chart picture to the particular requirements. This is possible because the chart picture is produced only during operation. It is possible to produce the relevant shallow water contour for a supertanker with a draught of 25 m or for a ferry with a draught of only 3 m. The presentation library controls this via adjustment of the safety depth/safety contour.

Automatic updating is much faster, easier and also less prone to error than chart adjustment currently laboriously carried out manually with a considerable time lag. Updating can even be called up on a digital telephone or via satellite, and incorporated instantaneously. ECDIS makes seafaring easier and thus also safer.

Precision navigation with ECDIS Bridge passage

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A Practical Update To Electronic Charting 1. Introduction Electronic Chart Systems have been available for a decade and their main benefits are well recognised. Until two years ago the cartography came from private companies. Today there are new choices with Hydrographic Offices providing official electronic chart services. The UK HOs world-wide catalogue of over 2300 ARCS raster charts has been a major factor in building confidence in the market with 110,000 ARCS charts and 1200 systems sold in little more than 12 months. The NOAA/BSB raster chart catalogue of 1016 official raster charts has been very successful in the US with chart and PC-based systems sales of 750,000 and 10,000 respectively (July 1997). These charts have gained the ascendancy in their respective markets because of their quality, up-to-dateness and official government backing. Both official formats are supported by chart update services. The BSB format also provides pilotage and photographic information add-ons. Similar developments are underway in Europe. A lively raster versus vector debate has arisen and this chapter explains the difference between the chart types and their relative strengths and weaknesses. With the advent of official raster charts a new Raster Chart Display System (RCDS) performance standard has been submitted to IMO. This has been put into context against ECDIS and ECS. In the course of considering RCDS the IMO have requested trials and user feedback. To show how electronic chart regimes are forcing greater awareness of some long standing technical issues, you need to attend to horizontal datum shifts between GPS and charts. 2. System Types 2.1 Electronic Chart Display and Information Systems (ECDIS) Only one performance standard has been approved at IMO, and that was for ECDIS in November 1995. This standard applies to vessels governed by the SOLAS convention who would comply with the carriage requirement for charts with an ECDIS system using Electronic Nautical Charts (ENCs).

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The chart data used in an ECDIS must conform to the Electronic Nautical Chart (ENC) S-57 specification. There are few ENCs available today and without an ENC an ECDIS is not an ECDIS. An ENC must be issued for use on the authority of government authorised hydrographic offices. 2.2 Raster Chart Display Systems (RCDS) Recognising the delays in implementing ECDIS, various hydrographic offices identified a need for alternative official chart data to connect the small pockets of ENCs expected over the next few years. This led to the development of the Admiralty ARCS raster chart and NOAAs BSB raster chart. Both formats come from the same production process used for paper charts and are in every respect identical to the paper versions. Of course, the electronic version has many more capabilities than paper, one of the most important being the ability to automatically merge chart updates (notices to mariners). A RCDS performance standard has been submitted to IMO. This performance standard is modelled very closely on the ECDIS performance standard and incorporates important requirements including: Continuous chart plotting Chart updating. At least the same quality of display as the hydrographic office paper chart Extensive checking, alarms and indicators concerning the integrity and status of the system. Route planning and voyage monitoring. For Mega yachts and other non-SOLAS vessels RCDS is a useful standard against which to measure the systems on offer. 2.3 Dual Fuel Systems A Dual Fuel System is one that is either an ECDIS or RCDS depending on the type of chart data in use. ENCs are scarce so there are few opportunities to use ECDIS whereas RNCs are available now in large numbers and can perform two important functions:

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Provide official electronic chart coverage for areas not covered by ENCs Provide link coverage between the ENCs that are available. For the future, a system should provide a choice of cartography, whilst ensuring that navigation calculations are consistent, regardless of the background chart. For example, in my companys system, Navmaster, world-wide variation is not derived from charts, and tidal stream is calculated from validated tidal data models, rather than from chart-specific data. Thus when a route is calculated, the result will be constant, whether the plan is drawn on a raster or a vector chart. 2.4 Electronic Chart Systems (ECS) An ECS is a system that does not conform to either the ECDIS or RCDS performance standards. There are no official performance standards applicable to this type of system. The IMO are working on an advisory document Guidelines for the use of ECS. The rule of thumb to apply is that a system is an ECS if:

It is using chart data (of any type) which is not issued under the authority of a government authorised hydrographic office.

Vector chart data is not in S-57 format. The system does not meet the standards of either ECDIS or RCDS performance

standards. 3. Chart types 3.1 Privately produced vector Privately produced vector charts are generally manufactured from scanned hydrographic office paper charts. The scanned image is then digitised by tracing the lines and features on the chart. This vectorisation process stores chart features in layers which can be redrawn automatically at an appropriate size as you zoom into the chart. You can add or remove categories of data such as spot depths, depth contours, navigation marks etc. In some systems you can query specific chart items, eg to get more information on a navigation light. The grouping of the data mirrors the paper chart regime. However the nature of the vector display is such that the chart data is not displayed electronically as it was compiled (as a paper document) and the original cartographic design of the paper chart is lost. Most systems automatically decide on the information to be displayed, depending on the level of zoom, to avoid the image becoming cluttered.

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Hence a new operational regime has to be developed to take into account the implications of: 1. Adding or removing layers of data 2. Zooming and seeing more or less data appear according to the level of zoom 3. Displaying the chart at a larger scale than the source paper chart 3.2 Official Raster There are two official raster chart formats

ARCS (UKHO) and Seafarer (Australian HO) both produced in the UK HOs proprietary HCRF format. ARCS is updated weekly with the same information as the weekly Notice to Mariners used to correct BA paper charts. Seafarer is updated monthly on a similar basis.

BSB raster charts contain all the detail found in NOAA paper charts, with updates published every 30 days. Weekly Notice to Mariner updates will be available in the second quarter of 1998. These will be distributed via the Internet and will be completely in-sync with the US Coast Guard, NIMA and Canadian notices.

Raster charts are direct facsimiles of paper charts and directly mirror the paper chart regime. The cartographic design (ie the chart data which should be displayed at a given scale) is maintained. Raster charts are often referred to as being simple images. Far from being simple, official raster charts incorporate considerable meta data which allows all chart information: notes, source diagrams, tidal diamonds, horizontal and vertical datums etc, to be displayed clearly and quickly. They are very accurate representations of the original paper chart with every pixel referenced to a latitude and longitude. Horizontal datum shifts are included with each chart to enable the chart and any information overlaid on it, to be referenced back to WGS-84. Chart file sizes are larger than their vector counterparts but redraw times are not significantly slower than commercial vector charts. A common misconception is that all raster charts are produced by the same simple technology. The following table, compiled from information supplied by BSB Electronic Charts and the UK HO, indicates variations between raster chart types.

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Feature ARCS BSB Maptech Government authorised Yes

Yes No

Entire catalogue always up-to-date to latest notice to mariner

Yes Yes (from Qtr 2 1998)

No

Update service Weekly Weekly (from Qtr 2 1998)

not known

Original scan from:

stable colour separates used for printing paper charts

stable mylar film originals used for printing paper charts

paper copy

Scan resolution 1016 dpi 762 dpi 250 dpi Chart resolution 127 dpi1 256 dpi 160 dpi Anti-aliasing2 Yes No3 No No of points used to relate the chart image to Lat/Long co-ordinates.

Pixel to position conversion is by calculation and is accurate to 1 pixel.

10-20, pixel to location conversions are also provided, accuracy depends on the printed chart

4

Geodetic datum shifts

Yes Yes No

Integrity checks 32 bit CRC check on original and updated image

Byte checksums are included in chart file

Not known

Liability UK government accept liability on HO products. US Gov accepts liability for errors on NOAA charts

Not accepted

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3.3 Electronic Nautical Chart (ENC)

One universal data format is defined for ENCs. The key factors which differentiate ENCs from all other types of electronic chart are:

ENCs must be issued under the authority of a government authorised hydrographic office.

All chart data is referenced to a global geodetic datum - WGS84 (the datum used by GPS).

Every single item on the chart, whether a spot depth, a navigation mark, a point on a depth contour, is attribute coded, and can be interrogated for information or used in calculations.

The data is delivered in cells to provide seamless data for the task in hand. In other words there is no direct correlation to the paper regime. The cell structure ranges from harbour to ocean data sets.

Since the data is fully scaleable, the user only has to define a view area for an appropriate level of data to be automatically presented to him. If he wishes to add or remove data, then the structure of the data allows information to be grouped into layers and turned on or off as required.

Individual contour lines can be defined as safety contours with anti-grounding warnings given based on the ships nearness to them.

3.4 Chart summary

Charts, whether produced officially or by commercial companies, should offer understandable standards of accuracy and reliability and have a clearly defined chart update policy.

The charts should be up-to-date, ie charts which have been corrected with all the official notice to mariner corrections that have been issued.

4. Feedback from RCDS Users The majority of RCDS users in trials have identified considerable safety and efficiency benefits over the use of paper charts. This followed from the integration of RCDS and

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GPS to provide instant access to the latest positional information and the many extra functions provided by RCDS compared to the paper chart including:

Real-time position plotting Passage monitoring Passage planning Route and waypoint management The potential to reduce the navigators workload in carrying out chart corrections

More trials are underway to provide further evidence of the safety and effectiveness of RCDS. PC Maritimes Navmaster Professional is being used in 2 trials: one by Shell Internationals Euplecta, trading in the Caribbean, and one by a Shell UK vessel trading around the UK and European coastlines. 5. Training Most systems claim to be easy to use and indeed most probably are - if you have a reasonable grounding in PC operating systems and how modern software applications are designed and work. However the systems we are talking about here are not simple. They have to handle large numbers of electronic charts; process data from EPFSs and other marine instruments; check the integrity of data as it comes in; maintain databases of routes and waypoints; monitor progress against plan; produce passage plan reports, etc. There is a lot to learn in order to work with the system effectively. The need for manufacturers training is under-estimated. To use a system effectively the end user must have a full understanding of the systems capabilities. To run hands-on training courses on a product and the background technology to commercial users one has to be hard pressed to cover all the ground in a few days. Sometimes it is either impractical or too costly to provide face to face training and the fallback is then the much derided User Manual (if all else fails read the manual). But a few hours spent working through description of the systems functions with examples can be a very productive way to learn. The user manuals generally allow any reasonably computer-literate person to acquire a sound understanding of the system in a few hours.

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However it has to be emphasized that it is not the manufacturers role to teach the foundations of navigation; or how Windows or other operating systems work; and if there are any deficiencies in these areas separate training should be provided. 6. Geodetic Datum A reference system for specifying positions on the Earths surface. Each datum is associated with a particular reference spheroid which can be different in size, orientation and relative position from the spheroids associated with other horizontal datums. Positions referred to different datums can differ by several hundred metres Having just said that it is not the manufacturers role to provide foundation navigation training there are aspects of the technology, which should be drawn to attention. A navigational chart is referenced to two datums: one horizontal, for latitude and longitude, and one vertical for depth and height. The issue of geodetic datum shifts is not a concern for ECDIS since all ENCs should be referenced to WGS84, but it does affect paper charts, RNCs and privately produced vector charts. The issue arises because the earth is not a perfect sphere. Over the centuries mapmakers have devised local models of the earths shape. Because the earth is not a regular shape the accuracy of each datum will vary as you get further from the specific location for which it was defined. Hundreds of different datums exist to define positions; examples are OSGB36, European 1950, Indian, etc. Satellite systems require a global datum and GPS positions are based on the World Geodetic System 1984 (WGS-84) which is a model of the entire earth. Problems arise when you are receiving positions based on one datum and plotting them on a chart which is based on a different datum. Figure 1 illustrates the range of latitude and longitude positions which could be derived for the same real location, depending on the datum used. Further examples follow: in the English Channel all Admiralty charts covering the English coastline are in OSGB36. All Admiralty charts covering the French coastline are in European 1950. Admiralty charts covering both sides of the channel tend to be in OSGB36. Consequently if you plot a position on an OSGB36 chart and then move to an European 1950 chart without accounting for the shift you will have introduced an error. Figure 2 indicates the magnitude of the error. In some parts of the world, the difference between WGS 84 and the local datum can be quite significant as shown in Figure 3 It has applied to the paper chart regime for as long as satellite navigation has been in use. The solution is to maintain positions in WGS-84 and apply the published shift every

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time you change chart. In practice, few navigators do this on paper, probably because they feel that they are not navigating to a precision at which these inaccuracies would be important. However in the electronic regime there is a new phenomenon, which is the illusion of pinpoint accuracy conveyed by GPS positions to two or more decimal places of a degree and by the automatic and frequent position plotting. GPS errors For civilian users GPS is artificially degraded to give a probability of the horizontal error being less than 100 metres for 95% of the time and less than 300 metres for 99.99% of the time. Differential GPS (DGPS), which is becoming more widely available is accurate 6.1 GPS errors and datum considerations So GPS positions already inaccurate to a certain degree are made more inaccurate by plotting on charts of different datum. Most GPSs have built in datum transformations so that you can set the machine to output positions in a local datum. But there are four problems with this: to +/- 5-10 metres (which may be more precise than the accuracy of the chart).

1. There is no standard applied to transformation formulae; two different GPSs may use different formulae and output different results. They provide a solution which is averaged over a wide area. Any error in the transformation can range from say 25m to much more at the fringes of the area covered by the datum. The resultant errors can be large compared to the accuracy of DGPS.

2. It is hard to ensure that the GPS is switched to the correct datum each time a

chart is changed.

3. GPS positions may be simultaneously fed to other instruments, eg ARPA, autopilot, expecting to receive the data in WGS84 co-ordinates.

4. Some GPS manufacturers apply the datum transformation to all waypoint

positions held in memory when a datum other than WGS-84 is selected for the display of positions. The point here is that you must be aware of the actions taken by your equipment.

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6.2 Datum management A better strategy is to maintain the output of GPS in WGS-84. In the case of Admiralty paper charts, a shift from WGS-84 to the local datum is printed on the chart. If the Admiralty has published a figure it means that they have reconciled the original survey to WGS84 and that the published shifts can be used with confidence. There are a number of Admiralty charts where it has not been possible to reconcile the original survey data against WGS-84. In this case no shift values are published. Under these circumstances you are at least aware that plotted positions are to be treated with caution. Summary of situations where safe navigation is affected by datum mismatches. (equally applicable to paper and electronic regimes) 1. Plotting of positions from GPS or other EPFS on non-WGS84 charts 2. Moving overlaid information between charts of different datum (eg waypoints or

routes). 3. Taking waypoint or other positions off non-WGS84 charts and transmitting them to

GPS. 4. Calculation of waypoints from, for example, great circle algorithms Of course this

emphasises the need to exercise standard navigation practice and not rely on positional information from just one source. Every opportunity should be taken to cross-check against all other available sources, visual, radar, etc. One of the great benefits of software is that it can automate the management of datum shifts. A modern chart format such as ARCS has the shift data built in and with this an RCDS can keep track of the datums of positions of all types, including vessel position and track, waypoints and any other overlaid point on the chart, and adjust them to the local geodetic datum as required. For this to work it is important that the GPS is always set to output WGS-84 positions. Ideally the GPS should identify the datum it is set to within the NMEA sentence output to the chart plotter. Unfortunately and surprisingly very few GPS manufacturers output this vital information although there are calls for the mandatory inclusion of a geodetic datum code with every position location message. Equipment receiving such a message can then automatically check that datums are correctly matched. This is an area where you, as customers, can reasonably ask that chart manufacturers provide datum shift parameters with all their charts; that GPS manufacturers output datum information and that ECS and RCDS systems should manage datums as outlined.

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8. Summary of Questions to Ask of an ECS \ RCDS system

1. To what extent does the system conform to either the ECDIS (if vector) or RCDS (if raster) performance standard?

2. Does the system offer choice of cartography preferably with both vector

and raster types?

3. Are the charts supplied with the system up-to-date at the time of sale?

4. Does the manufacturer provide training or have a network of dealers authorised to train on their behalf?

5. Is the User Manual good enough for self training?

6. Does the chart format provide datum shift values?

7. Does your GPS output the datum with positional information?

8. Does the ECS / RCDS manage horizontal geodetic datums?

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Summary of chart type differences

The following tables summarise the features, strengths and weaknesses of each chart type in relation to one another.

Equivalence to the paper chart

Privately produced vector charts

Official Raster (RNCs)

ENCs

Generally a copy of the paper chart

An exact replica of the paper chart

All data merged into cells

a different image to the original paper chart is presented at all levels of zoom and scale

The same image as the paper chart is always presented. The chart is more equivalent to the paper chart than any vector chart including ENCs

No resemblance to the paper chart

Symbols and colour vary with manufacturer.

Symbols and colour are the same as the paper chart equivalent.

The IHO publication S-52 defines new colours and symbols for ENCs.

Accuracy, reliability and completeness vary with manufacturer.

RNCs are as accurate, reliable and complete as the paper version.

ENCs should be more accurate and reliable than the paper version.

A new operational regime is required

The same operational regime as paper charts is followed.

A new operational regime is required

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Chart Integrity Privately produced

vector charts Official Raster

(RNCs) ENCs

Produced by private companies

Produced by or under the authority of government authorised hydrographic offices

Produced by or under the authority of government authorised hydrographic offices

Unofficial

Official

Official

Generally no responsibility is accepted

Responsibility is accepted for chart data in terms of its completeness and accuracy in comparison with the equivalent paper chart.

Responsibility is accepted for chart data in terms of its completeness and accuracy.

Is unlikely to become legally equivalent to the paper chart

May become legally equivalent to the paper chart

Is legally equivalent to the paper chart

It may be possible to change original chart data

The chart data is tamper proof

The chart data is tamper proof

Charts can be zoomed (ie the display of a single chart is magnified or reduced) without restriction. Chart detail varies depending on the level of zoom.

Chart zoom should be limited to a level that does not break up the image Information displayed on the chart remains unaltered.

Charts can be zoomed in or out without restriction. Chart detail varies depending on the level of zoom.

Quality Control varies with manufacturer

Quality Control is government standard

Quality Control is government standard

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Chart corrections Privately produced


(RNCs) ENCs

Up-to-dateness of charts varies with manufacturer

Charts are up-to-date at the point of sale

Charts will be up-to-date at the point of sale

It is difficult to determine the updating policy of private manufacturers

Chart data is maintained up-to-date to clearly stated standards

Chart data is maintained to a clearly defined standard

varies with manufacturer

On demand updates for leisure users

not applicable


Subscription updates for commercial users

Subscription updates available


Automatic integration of chart updates

Automatic integration of chart updates

Safety Privately produced


(RNCs) ENCs

Geodetic datum shift to WGS84 may not be provided

Chart data includes geodetic datum shift to WGS845.

All data is referenced to WGS84

Chart data can be removed from the display. Significant navigation information may be inadvertently removed.

Chart data cannot be removed from the display. The user cannot inadvertently remove significant navigation information

Chart data can be removed from the display. Significant navigation information may be inadvertently removed

For some charts it is not possible to reconcile the original survey data against WGS84 and no geodetic shift data is available.

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INTEGRATING ECDIS WITH OTHER ELECTRONIC SYSTEMS

As per IMO performance standards, an ECDIS should be connected to a ships position-fixing system, to a gyro compass and to a speed and distance measuring device.

For any ships without a gyro compass, ECDIS should be connected to a marine transmitting heading device. However, most modern ECDIS already integrate the majority of navigational systems on modern bridges but are subject to the condition that their integration does not degrade the performance of any equipment providing sensor inputs or the performance of ECDIS itself. The benefits of integrating additional navigational systems will include providing the mariner with a greater perspective of the navigational picture whilst increasing situational awareness. The navigation officers work load decreases as information relating to the safe navigation of the ship (for example, depth, speed and course) can be readily viewed on the ECDIS display as well as other important information. Additional navigation systems incorporated into ECDIS can include but are not limited to:

AIS (automatic identification system) RADAR (radar image overlay RIO) VDR (voyage data recorder) Echo sounder NAVTEX Meteorological instruments such as anemometers (measuring wind speed)

Navigation officers should be aware of which electronic systems are providing sensory inputs into their onboard ECDIS and the consequences of the inputs failing or malfunctioning due to local electronic system failure. If GPS sensors fail to provide position fixing input to the onboard ECDIS, navigation officers must be fully ready and practiced in carrying out position plotting directly onto the ECDIS using traditional position fixing methods, for example visual bearings, radar ranges, radar bearings and transits. There is the risk with ECDIS that navigators may become dependent on monitoring and that when a sensor fails, the navigator must return to first

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principles to deal with the situation. This in turn may lead the navigator to incur additional errors in dealing with the situation known as knowledge based errors. Only through training, in-depth knowledge of ECDIS and its integrated electronic systems and a defined procedure for sensory failure, can the navigator expect to effectively deal with input failures to ECDIS. There should be a procedure within the safety management system (SMS) in the event of sensory input failure to ECDIS. A checklist should be established on the bridge with clear instructions on how to deal with sensory input failures and how it may affect the safe navigation of the ship. The following points should be addressed in such a checklist:

has the failed sensory input been identified? has the master been informed and does an additional navigation officer need to

take over the watch? has the failed sensory input affected the navigation of the ship? implement back-up protocols as per the SMS procedure to ensure safe

navigation, for example traditional position fixing methods has the failed sensory input affected any other electronic systems? has a rectification action been identified to repair the sensory input? does the ships passage plan need to be amended?


ECDIS BACK-UP REQUIREMENTS Electronic navigation systems cannot be guaranteed to be 100% failsafe; with this in mind, there must be some form of back-up or redundancy to cover ECDIS failure. IMO performance standards require the overall system to include both a primary ECDIS and an adequate, independent back-up arrangement to ensure the safe takeover of ECDIS functions without resulting in a critical situation. The independent back-up arrangement must allow the safe navigation of the ship for the remaining part of the voyage in case of ECDIS failure. The flag state must approve the ECDIS back-up arrangement to ensure it is in accordance with IMO performance standards; however, some flag states may delegate the ECDIS approval process to a recognised organisation. The following back-up options are generally accepted as meeting SOLAS carriage requirements:

1. For ships using ECDIS as their primary means of navigation (no paper charts), an additional and independent ECDIS shall be provided as a back-up. The back-up ECDIS should be connected to an independent power supply and connected to systems providing continuous position-fixing capability.

When the ECDIS is being operated in Raster Chart Display System (RCDS) mode using RNC data due to lack of suitable coverage of electronic navigational charts (ENC), then an appropriate folio of up-to-date paper charts must be maintained for areas where only raster chart coverage is available.

2. For ships using ECDIS as an aid to navigation, the ship must carry and maintain

an appropriate folio of up-to-date paper charts. The ECDIS should be able to operate in a normal capacity even when it is connected and supplied by an emergency source of electrical power. Change over from one source of power supply to another, including any interruptions in electrical supply should not require the equipment to be manually reinitialised for a period of 45 seconds.

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Paper Charts For ships using ECDIS as their primary means of navigation, paper charts may still need to be carried in order to comply with the new carriage requirements for ECDIS, particularly if the ECDIS is being used in RCDS mode for certain parts of the voyage. The IMO performance standards require that for ships navigating in areas where only raster chart coverage is available, the ship must have an appropriate folio of up-to-date paper charts.

Member states of IMO have either issued or are in the process of issuing their own interpretation of the requirements for ECDIS carriage, performance standards, chart coverage and training through merchant shipping notices or equivalent. An example is drawn from Bermuda Shipping Notice 2011-010 Introduction to BNWAS and ECDIS, which states: For Bermuda ships this back up set of paper charts when required for operation in areas without vector chart data may be a reduced set sufficient to navigate in the event of an electronic chart failure. Operators should determine, for each ship that requires these, an appropriate set of paper charts based on the risks involved. The sufficient set of paper charts should be based on a suitable risk assessment of the trading area where there is insufficient ENC data and only RNC data available. The UKs Maritime and Coastguard Agency (MCA) has stated in its Marine Guidance Notice (MGN) 285(M+F) Electronic Charts Use of risk assessment methodology when operating ECDIS in RCDS Mode that prior to MCA approval for ECDIS in RCDS mode as a primary means of navigation, a risk assessment is to be undertaken by suitably experienced personnel in the field of risk assessment and it is not intended that the entire task of undertaking the risk assessment should lie exclusively with shipboard personnel. The MCA makes it clear that overall responsibility for the risk assessment remains with the shipping company managers who need to ensure that adequate resources have been allocated for the task. Similarly, the Republic of the Marshall Islands states in its Marine Notice No. 7-041-6 Nautical Chart and Publication Carriage Requirements that the owner or master is to decide the number of charts needed to satisfy the requirements of a back-up system. The Marshall Islands specify that the administration has no minimum or maximum requirement for paper charts but these should be of a sufficient number to ensure safe navigation to a port of safe refuge in the event that electronic chart navigation is unavailable.

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As can be clearly seen, flag states may adopt different interpretations to the risk assessment process of operating in RCDS mode and retaining an appropriate number of paper charts onboard. To avoid confusion and misinterpretation, the ships relevant flag states should be consulted to determine the procedure on defining and approving the appropriate number or folio of paper charts needed to comply with IMO performance standards requirements. IHO CHART CATALOGUE DETERMINING ENC, RNC AND PAPER CHART COVERAGE To determine ENC/RNC chart coverage and whether paper charts are required in a particular trading area, an online chart catalogue produced by the International Hydrographic Office (IHO) provides details on the exact areas of ENC/RNC coverage. The information is gathered by the IHO from member states hydrographic offices and updated as required when new charts are created. RISK ASSESSMENTS TO DETERMINE CHART COVERAGE AREAS WHEN USING ECDIS AS A PRIMARY MEANS OF NAVIGATION Masters and navigation officers preparing passage plans will have to conduct a risk assessment for areas where the ship will be trading to determine if there is suitable electronic chart coverage and whether an appropriate folio of paper charts (APC) is needed. Not all sea areas are covered by ENC charts.


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MAINTAINING and UPDATING ECDIS

It is important to remember that ECDIS comprises three elements:

Hardware, Software and Data.

ECDIS operators must ensure that their software always conforms to the latest IHO standards (www.iho.int) and that an officially recognised distributor/service provider delivers regular service updates on software and official ENC/RNC data. All masters and navigation officers should be fully aware of how to update and maintain the onboard ECDIS. It should not be left for the designated navigation officer to have sole knowledge on the updating procedure and process. Updating procedures should be covered under ECDIS generic training but, more importantly, also under the type specific training as different ECDIS models vary in their updating process. ^ An up to date electronic navigational chart (ENC)


Keeping the ECDIS fully up to date should be a high priority for the bridge team and should be treated as equally important as normal paper chart corrections. ECDIS updates normally coincide with weekly paper chart corrections. Updates can be sent via email and transferred onto CD or USB flash drive for updating the ECDIS. Any device used to transfer ECDIS updates should be a dedicated unit for that sole purpose only and be free of any viruses that may corrupt ECDIS software. Software and large ENC/RNC updates are generally received on a data CD and delivered to the ship, particularly where files are too large or expensive to send via email. ECDIS should store and display on demand a record of updates, including the time of application to the ECDIS database, known as the system electronic navigational chart (SENC). This record should include updates for each ENC until it is superseded by a new edition. In order for the ECDIS to fully comply with IMO performance standards and display all relevant digital information contained within an ENC, it should be updated to the latest version of the ENC product specification. Additionally, any ECDIS that is not updated to S-63 Data Protection Standard may fail to decrypt or properly authenticate the ENC. Failure to update your ECDIS properly may result in the latest charted features not being displayed or failure of alarms/indications even if new charted features have been included in the ENC. An ECDIS that is not updated correctly and on a regular basis may not meet the chart carriage requirements as set out in SOLAS regulation V/19.2.1.4.

Temporary And Preliminary (T&P) Notices Temporary and preliminary notices have not yet been fully integrated into ENC or RNC data by all National Hydrographic Offices. Caution must be exercised when navigating solely with ECDIS as some ENC or RNC data may not take account of temporary or preliminary notices. The International Hydrographic Office has identified this problem and developed a working group to address this. The only guaranteed source for T&P information at present are Notices to Mariners (NM) issued by National Hydrographic Offices.

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The United Kingdom Hydrographic Office (UKHO) has recognised the need to include T&P notices within its ENCs by including this information in its Admiralty Information Overlay. This tool allows the notices to be displayed as an overlay to the ENC in the Admiralty Vector Chart Service (AVCS), thus assisting the navigator in readily identifying the location and content of a notice during passage planning and the voyage itself. Members should issue guidance within their onboard bridge procedures and SMS on how to handle and update ECDIS with T&P notices. Navarea, Navtex And Locally Broadcasted Warnings Navigational warnings transmitted by satellite communications (for example, SAT C telex), NAVTEX receiver and radio-broadcasted warnings are by nature more short term and urgent than temporary or preliminary notices. Navigators using paper charts as a primary means of navigation will normally plot urgent warnings by pencil on the paper chart itself to ensure that there is clear record and other navigators can clearly see any new plotted dangers in relation to the position of the ship. Navigators using ECDIS should be aware of the ability to plot new dangers on electronic charts through the use of the Marine Information Objects (MIO) capability. The purpose of the MIO is to highlight navigational warning information on the electronic chart. Key points

know how to update your ECDIS (all navigational officers) know how updates are received and their frequency coordinate with your electronic chart supplier for arranging delivery of new ENC/RNC data in good time, particularly if the ship changes

trade at short notice recheck your existing passage plans after updating ECDIS as new dangers may existmake use of the MIO capability to add received navigational

warnings navigational audits should include checking ECDIS updates

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ECDIS Advantages & Limitations Paper to Digital Ship Conference

(Nanda Kumar Elektronik Lab India - Dec 2003) Development of ECDIS is probably the longest birth ever known to a mariner, beginning in the mid 1980s and still in labour. Reason for this slow progress is the lack of chart availability and inconsistent flag state legislation requirements. ECDIS is an acronym for Electronic Chart Display and Information System. At its simplest, an ECDIS consists of a database of electronic charts, together with the hardware and software needed to display simultaneously the charts and the ships own position (obtained from a GPS or another positioning sensor), and to perform navigational tasks such as route planning, route monitoring, measurement of distances on the chart, etc. One of the most important features of ECDIS that makes it a unique aid to navigation, is the capability of generating alarms (anti-grounding, off route, etc.) based on input from sensors and analysis of chart information. Standards To be defined an ECDIS, an Electronic Nautical charting system (ENC) must comply with a number of international standards and regulations, amongst which the most important are those issued by the International Hydrographic Organization (IHO) and the International Maritime Organization (IMO): IHO Special Publication S-57, IHO Transfer Standard for Digital Hydrographic

Data. The S-57 Edition 3.1 (also refered to as S-57/3) was released in November 2000 following a familiarization period of one year. The previous edition (3.0), was published in November 1996, and was frozen, (i.e. remain unaltered), for a period of four years in order to facilitate ENC production and to provide stability for ECDIS manufacturers.. It describes the standard (i.e. the data model and format) to be used for exchange of Electronic Navigational Charts (ENC) between Hydrographic Offices, ECDIS manufacturers, mariners, and other data users.

IHO Special Publication S-52, Specification for Chart Content and Display

Aspects of ECDIS, 5th Edition, December 1996 (hereinafter called S-52). It provides specifications and guidance regarding the issuing of ENC, their

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updating, and their display in ECDIS(including details about colours and symbols to be used for on-screen presentation).

IMO Resolution A/817, IMO Performance Standards for ECDIS, December 1995

(hereinafter called IMO PS). It describes the minimum performance standards for ECDIS, with reference to hardware, software, ENC and updates, user interface, integration with positioning sensors, radar and other devices, etc.).

Legal Equivalency With Paper Charts With a type approved ECDIS, the International Maritime Organisation (IMO) allows electronic navigational charts (ENCs) - official vector charts produced according to the IHO Standard for Digital Hydrographic Data Special Publication No. 57 (S-57/3.1) - to be used for primary navigation in place of paper charts, provided there is a suitable backup (e.g. a second ECDIS with a separate power supply, or an appropriate folio of up to date paper charts). In order for an ECDIS to be the legal equivalent of paper charts, the following conditions must be true: The ECDIS must be type-approved.

The system must be complete with a type-approved back-up system, that

must enable instant and safe take-over of navigation and continuation of the voyage if an ECDIS malfunction occurs (the back-up system may range from a radar with additional navigational function, to be used together with paper charts, to a second, fully compliant ECDIS).

The system must display official ENC, issued by a national Hydrographic

Office. The ENC must be up to date.

If the system complies with all above requirements, it is considered equivalent to the navigational charts required by the SOLAS (Safety Of Life At Sea)Convention, meaning that paper charts do not have to be carried on board. However, as soon as the system fails to match one of the requirements, the legal equivalency decays. In particular, a type-approved ECDIS displaying data other than official ENC (such as vector chart supplied by a data producer other than an Hydrographic Office, or raster charts issued

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by an Hydrographic Office) is not equivalent to paper charts; in this case, the mariner should not rely on the ECDIS as the only source of navigational information, and updated paper charts must be available on board. Benefits ECDIS will not make accidents go away, but that they will help to prevent collisions. Reducing human error is the most significant contribution ECDIS will have. ENCs will give a better representation of the actual and dynamic environment than paper charts. ENCs will not only contain more information than paper charts, but that procedures for updating ENCs will also be better, with ENCs being more up to date than paper charts. The majority of ECDIS / RCDS users in trials have identified considerable safety and efficiency benefits over the use of paper charts. This followed from the integration of RCDS and GPS to provide instant access to the latest positional information and the many extra functions provided by ECDIS/ RCDS compared to the paper chart including: Real-time position plotting Passage monitoring Passage planning Route and waypoint management The potential to reduce the navigators workload in carrying out chart corrections

Limitations 1) Lack of Global coverage Complications in obtaining worldwide chart coverage mainly due to the policy differences between the national Hydrographic authorities. The lack of official ENC makes things just worse. Even if a number of Hydrographic Offices have started ambitious programs of ENC production, very few official electronic charts in S-57/3 format are available today. The result is that ECDIS users have to supplement ENC data with non-ENC electronic charts, such as

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Commercial databases of electronic charts, produced by organizations other than Hydrographic Offices

Electronic charts produced by Hydrographic Offices, not compliant with S-57/3

(e.g. vector charts in formats other than S-57/3, raster charts, etc.).

Required the use of the so-called dual-fuel ECDIS: a system fed with both ENC and non-ENC electronic charts.

Since the ECDIS operates in non-equivalent mode when using non-ENC charts,

S-52 and the IMO Performance Standards require that these are not mixed with the ENC. Therefore, they must be loaded in the ECDIS into a separate storage area and must remain clearly distinguishable from official charts even after compilation in the SENC.

It must be stressed that quality of non-ENC charts may vary to a large extent,

and their format may be very different from S-57/3. This adds further complication (and potential problems) to the task of the SENC

ECDIS Course Notes - 2012

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Transcript of ECDIS Course Notes - 2012