Admiralty Vector Chart Service - United Kingdom Hydrographic Office

Including the Admiralty Information Overlay
User Guide 2.3

Admiralty Vector Chart Service Version 2.3
User Guide
The United Kingdom Hydrographic Office
Admiralty Way, Taunton, Somerset, TA1 2DN, United Kingdom
Tel: +44 (0)1823 723366
E-mail: customerservices@ukho.gov.uk
www.ukho.gov.uk
UKHO 2012 All Rights Reserved
The copyright in this document, which contains information of a proprietary nature, is vested in UKHO.
The content of this document may not be used for purposes other than that for which it has been supplied
and may not be reproduced, either wholly or in part, in any way whatsoever.
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Table of Contents
Introduction........................................................................................................................1
Service Overview ...............................................................................................................2
What is AVCS?..................................................................................................................................................2
Buying AVCS.....................................................................................................................................................2
ENC Selection ....................................................................................................................................................2
Transit folios .......................................................................................................................................................3
Regional folios ....................................................................................................................................................4
Port folios............................................................................................................................................................5
Exceptions ..........................................................................................................................................................5
Licence Period ..................................................................................................................................................5
AVCS Certificate.................................................................................................................................................6
Getting Started...................................................................................................................7
Before You Start ...............................................................................................................................................7
AVCS Start-Up Pack...........................................................................................................................................7
AVCS Licence.....................................................................................................................................................7
Replacement of AVCS Media and Files .............................................................................................................7
Data Cleansing ...................................................................................................................................................7
Loading Charts for the First Time...................................................................................................................8
Loading the Public Key.......................................................................................................................................8
Loading Chart Permits........................................................................................................................................8
Loading Base Charts ..........................................................................................................................................8
Loading Updates from the Base disks................................................................................................................9
Loading the latest Update CD ............................................................................................................................9
Maintaining the Chart Outfit ............................................................................................................................9
New Chart Permits..............................................................................................................................................9
Update CDs ........................................................................................................................................................9
Re-Issued Base disks.......................................................................................................................................10
README.TXT File............................................................................................................................................10
Cancelled ENCs ...............................................................................................................................................10
Licence Expiry ..................................................................................................................................................10
Adding Chart Coverage ....................................................................................................................................11
Support .............................................................................................................................................................11
Emergency Chart Permit Generation ...............................................................................................................11
AVCS Service Details ......................................................................................................12
About AVCS ....................................................................................................................................................12
ENC Cell Usage Bands and Identifiers.............................................................................................................12
Validation ..........................................................................................................................................................12
Authenticity .......................................................................................................................................................12
Updates............................................................................................................................................................12
Admiralty Information Overlay .......................................................................................13
What is the Admiralty Information Overlay? ...............................................................................................13
Installing the Admiralty Information Overlay...............................................................................................13
Compatible Equipment .....................................................................................................................................13
Installing Overlay Permits.................................................................................................................................13
Installing Overlay Data......................................................................................................................................13
Updating the Overlay........................................................................................................................................13
Using the Admiralty Information Overlay.....................................................................................................14
Displaying the Overlay......................................................................................................................................14
T&P NMs ..........................................................................................................................................................14
EP NMs.............................................................................................................................................................14
‘No Overlay’ Feature.........................................................................................................................................15
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Using the Admiralty Information Overlay in the Navigation Process................................................................15
Chart Carriage Regulations ............................................................................................16
Flag State Acceptance of ECDIS...................................................................................................................16
Mandatory Carriage of ECDIS .......................................................................................................................16
Port State Control...........................................................................................................................................16
Using Electronic Charts in ECDIS ..................................................................................17
Training............................................................................................................................................................17
Chart Accuracy ...............................................................................................................................................17
Source Data Quality........................................................................................................................................17
Chart Display Scale ........................................................................................................................................17
Chart Display...................................................................................................................................................17
Scale Minimum (SCAMIN)................................................................................................................................18
Contour Intervals ..............................................................................................................................................18
Overlapping ENCs............................................................................................................................................18
Use of other Chart Formats ...........................................................................................................................19
Settings and Alarms.......................................................................................................................................19
Procedures ......................................................................................................................................................19
Use of ECDIS with Global Positioning Systems (GPS).................................................20
Accuracy and Availability ..............................................................................................................................20
GPS Reference Datum and Chart Datums ...................................................................................................20
GPS Receiver Settings...................................................................................................................................20
Route Planning and Datums..........................................................................................................................20
Use of ECDIS with Radar ...............................................................................................................................20
ARPA Targets..................................................................................................................................................20
Using Radar as a check on vessel position.................................................................................................21
Troubleshooting / Problem Solving ...............................................................................22
Errors ...............................................................................................................................................................22
Standard Error codes when loading AVCS ......................................................................................................22
Decryption Failure.............................................................................................................................................22
Conversion Errors.............................................................................................................................................23
Copyright Information .....................................................................................................24
Annexes............................................................................................................................25
Table of Figures ..............................................................................................................................................25
Glossary ..........................................................................................................................................................26
Feedback ..........................................................................................................................27
Contact Details................................................................................................................................................27
Company Contact.............................................................................................................................................27
ECDIS Manufacturer.........................................................................................................................................27
Chart Agent.......................................................................................................................................................27
UKHO ...............................................................................................................................................................27
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Introduction
Thank you for choosing the Admiralty Vector Chart Service (AVCS). AVCS is an official, global, all-vector
chart service and is designed specifically to meet the needs of the international professional mariner, whilst
providing full compliance with carriage regulations.
AVCS provides you with Electronic Navigational Charts (ENCs), each of which conforms to the definition of a
nautical chart set out in SOLAS Chapter V Regulation 2.2. AVCS updates are provided weekly during the
licence period.
This guide is designed to help you gain maximum benefit from using the service, and should be used in
conjunction with your ECDIS User Manual.
Equipment specific AVCS User Guides are available for some popular ECDIS. These User Guides are
available from your Admiralty Chart Agent and can be downloaded from www.ukho.gov.uk/AVCS.
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Service Overview
What is AVCS?
The Admiralty Vector Chart Service is supplied by the United Kingdom Hydrographic Office (UKHO). It brings
together Electronic Navigational Charts (ENCs) from the world’s National Hydrographic Offices, and fills the
gaps in coverage with specially produced ENCs unique to the UKHO. The result is a comprehensive, official,
world-wide ENC service that can be used within Electronic Chart Display and Information Systems (ECDIS).
AVCS is aimed at international merchant shipping and covers the top ports of the world and the routes
between them.
AVCS also includes the Admiralty Information Overlay, a layer of additional Notice to Mariners (NM)
information which can be used in conjunction with ENCs to improve safety of navigation when using ECDIS.
The Overlay contains all Admiralty Temporary & Preliminary Notices to Mariners (T&P NMs) and provides
additional preliminary information that is specific to ENCs, such as reported navigational hazards that have
been incorporated on paper charts but have not yet been included in ENCs.
AVCS data is supplied on CD or DVD and maintained by weekly update CD or on-line. Individual ENCs and
folios of ENCs can be licensed for periods of 3, 6, 9 or 12 months, depending on the permissions granted by
the original producers of the ENCs.
Buying AVCS
ENC Selection
In order to make it as easy as possible to select the coverage required for a vessel, AVCS is provided as
individual charts and in geographically based folios giving world wide coverage.
All ENCs in AVCS can be selected on a chart-by-chart basis as ENC Units. These Units are the smallest unit
of sale allowed by the ENC producers and usually contain ENC data approximately equivalent to a paper
chart.
AVCS also offers a series of managed Folios, each of which contains all the ENCs required for its defined
purpose (e.g. transiting an area). Any relevant new ENC data that becomes available is included in the
appropriate AVCS Folio at no additional cost.
There are 3 types of folio available, designed to maximise utility and minimise the purchase of redundant
data:
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Transit folios
The world is divided into Transit areas representing convenient and well-understood ocean regions. These
contain predominantly Overview (band 1) and General (band 2) cell coverage, with Coastal (Band 3)
coverage where appropriate (at selected choke points, capes, straits and complex coasts).
Figure 1 AVCS Transit Folios
Each transit folio provides sufficient coverage for a vessel to pass safely through a region, if not engaging in
local trade. Only limited Coastal band coverage is included, Approach and Harbour band coverage being
available separately.
The objective with Transit folios is to save operators the expense of purchasing detailed coverage for regions
that they are just passing through, whilst including more coverage to negotiate the choke points.
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Regional folios
These folios are of much smaller geographical footprint than the transit folios, of which they are usually a
sub-area.
Regional folios generally include all Coastal (band 3) coverage within the folio’s footprint and, where Coastal
band coverage is not available (e.g. parts of Scandinavia), include Approach (band 4) cell coverage.
Figure 2 AVCS Regional Folios
The world’s ENC coverage at regional scales is rapidly growing. Where Regional Folios can be schemed
that provide sufficient coverage for navigation in the area they will be released in AVCS. In areas where
there is still insufficient coverage to populate a useful folio the individual charts are made available as ENC
Units.
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Port folios
Coverage of the world’s top ports is schemed into a set of Port Folios. Each contains the coverage
necessary to enter each port, with Approach (Band 4), Harbour (Band 5) and Berthing (Band 6) cells
grouped together into a single sales unit. In very complex areas where a number of ports share approaches
a single Port Folio has been schemed to provide the coverage required for all the ports in the area.
Figure 3 AVCS Port Folios
Typically, the operator will be able to choose just the Transit folios required to get from their current location
to a particular destination port, plus one or more Regional folios to provide more detail where necessary. The
vessel operator may then choose specific detailed coverage appropriate to the port(s) they will be visiting.
Exceptions
Norway and some other Scandinavian countries do not provide Coastal (band 3) coverage. Therefore
Regional folios in these areas include Approach (band 4) coverage which is consequently not included in the
Port folios within those regions
The St Lawrence Seaway has little Coastal (band 3) coverage available. Therefore the Regional folio
covering this area is comprised of all Coastal and Approach coverage (bands 4 and 5) available
Both the Suez Canal/Red Sea/Gulf of Aden and Malacca Straits areas are narrow challenging waterways.
Thus the Transit folios for these areas include all Overview, General and Coastal (bands 1, 2 and 3)
coverage available. Consequently there are no separate Regional folios for these areas.
Licence Period
The ENCs in AVCS are provided under a licence agreement that permits their use of defined periods of time.
ENC Units and Folios may be added to an AVCS licence at any time for periods of 3, 6, 9 or 12 months.
At the end of the licensed period the permits issued to access the ENCs will expire and ECDIS will no longer
apply updates to the ENCs. Users are warned in advance of the expiry of their permits through their
Admiralty Chart Agent and Admiralty e-Navigator Planning Station. Expiring ENC licenses may be renewed
up to a month before the date of expiry to ensure continuity of coverage.
ENC Units and Folios may be added to an AVCS licence even after all other ENC data on the licence has
expired. This means that a vessel returning from dry dock, for example, can continue to use the licence
number and details that were in use previously.
There are restrictions on the licence duration that can be offered for some ENCs. All Folios and Units are
offered for 12 month periods and, where possible, shorter periods. Please see the AVCS Pricing Schedule
for more information.
At the start of your licence period you will receive an Admiralty Vector Chart Service Start-Up Pack, Chart
Permit files and a copy of the End User Licence Agreement and a Schedule A from your Admiralty Chart
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Agent. The Chart Permit files unlock the specific Folios and Units added to your licence and the Schedule A
lists the licensed Folios and Units for your records. If you are using e-Navigator Planning Station you will not
receive a Schedule A as this information is provided in e-Navigator.
During the licence period an Update CD will be supplied weekly to enable your licensed data to be
maintained for Notices to Mariners. You will also be provided with all New Editions and replacement charts
within the licensed Folios and Units. These updates are also available by email and over the Internet by
using the Admiralty Updating Service or e-Navigator Planning Station.
In addition, any new ENCs that become available in the service and within the licensed Folios are
automatically provided at no additional cost. Where necessary revised Chart Permit files and a Schedule A
are also be provided.
AVCS Certificate
When you initially subscribe to AVCS, and when you extend the period for which you have licensed ENCs,
you will be supplied with an AVCS Certificate. The Certificate shows your vessel name, your licence expiry
date and certifies that all charts supplied in AVCS are ENCs that conform to the requirements of SOLAS
Chapter V.
The Certificate is supplied as a digital file alongside your Schedule A or through e-Navigator Planning
Station, can be printed if required, and will help you to satisfy inspectors that you are using carriage
compliant ENCs.
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Getting Started
Before You Start
Your Admiralty Chart Agent will provide you with the following materials when subscribing to AVCS for the
first time:
AVCS Start-Up Pack
• AVCS Quick Start Guide;
• AVCS User Guide;
• AVCS Base Disks (a set of CDs or a DVD labelled ‘Base’);
• AVCS Update Disk (a CD labelled ‘Update’);
• Admiralty Utilities installation CD (the Utilities CD is not required if you are using Admiralty e-Navigator);
• Admiralty Information Overlay CD (if you have a compatible display system and the Overlay has been
added to your licence);
• Admiralty Digital Data Services End User Licence Agreement (EULA).
The correct issue date for all Base CDs is published in the weekly Admiralty Notices to Mariners bulletin and
on the UKHO website at www.ukho.gov.uk/AVCS (click on the Licensing and Updating tab to view the AVCS
distribution and issue dates).
Please ensure that you have read and understood the terms of the End User Licence Agreement
before starting to use the Admiralty Vector Chart Service.
AVCS Licence
This may be supplied with the AVCS Start-Up Pack on hard media, e.g. floppy, CD, etc., separately by email
or directly from e-Navigator.
The initial licence pack will contain the following:
• A “Schedule A” (except when using e-Navigator), this is a PDF document listing the Folios and ENC
Units that the user is licensed to use. It also contains information relating “Home CD” where the licensed
ENCs are held. This is particularly useful as it prevents unnecessary loading of those CDs that do not
contain any licensed ENCs.
• A set of ENC Permit files (PERMIT.TXT and ENC.PMT) for each ECDIS installation.
• AVCS Certificate (a PDF document showing your vessel and licence details).
For an initial installation, or a reinstallation, of AVCS on an ECDIS you will need all of the above. If you are
applying a weekly update, you will only need the latest AVCS update disc and possibly a new ENC Permit
file. If you want to install additional coverage on the ECDIS you will need the latest base disc(s), the latest
update CD and a new set of ENC Permit files.
Replacement of AVCS Media and Files
Most Admiralty Chart Agents will have a stock of AVCS Start-up packs, so base and update discs can be
obtained from them. Usually digital files, such as ENC Permits, are sent as attachments to emails and these
may be stored in your email system’s inbox. If not, your Chart Agent will often hold copies of any permit files
previously sent to you.
Data Cleansing
New AVCS customers who had previously subscribed to other ENC services are strongly recommended to
remove (purge) all ENC Permits and ENCs from the system before installing AVCS. It is important to do this
to prevent previously installed ENCs becoming out of date if they are not licensed in AVCS. If the system is
not purged redundant ENCs may remain in the system database (SENC) and be available for use. However
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unlicensed ENCs cannot be updated and the user may be unaware of this if inadvertently navigating on one.
Please consult your ECDIS system manual for instructions on how to remove ENC Permits and ENCs from
the ECDIS.
Loading Charts for the First Time
The procedure for loading AVCS data varies from ECDIS to ECDIS, but the same general principles apply
and are outlined below. You should consult your ECDIS system manual for detailed instructions.
Loading the Public Key
ECDIS authenticates the source and integrity of ENC data from service providers against a pre-installed
Public Key. To ensure compatibility with the widest range of ECDIS, AVCS uses the PRIMAR Public Key.
Many ECDIS are pre-installed with the IHO Public Key and will fail to load AVCS until the PRIMAR Public
Key is installed. If the correct Public Key is not installed the ECDIS will report an Authentication Failure.
The PRIMAR Public Key is contained in a file called PRIMAR.CRT located in the root folder on any AVCS
Base or Update disk. The procedure for loading the Public Key is different on each ECDIS and will be
detailed in your ECDIS system manual. Specific instructions for some common models of ECDIS are
available on the UKHO website at www.ukho.gov.uk/AVCS.
New build ECDIS, type-approved against the latest IMO ECDIS Performance Standards (Jan 2009), will
report a warning when installing AVCS. The message reads as follows:
SSE26 - This ENC is not authenticated by the IHO acting as the Scheme Administrator
This warning can be ignored as the source and integrity of the ENCs are authenticated correctly against the
PRIMAR Public Key.
Loading Chart Permits
AVCS charts are copy-protected. Access to the data is provided by Chart Permits which are generated for,
and will only work on, the ECDIS for which they were ordered. These are normally supplied by email or from
e-Navigator and loaded into the ECDIS via floppy disk (the Permit disk), CD or USB memory stick. The Chart
Permits are contained in 2 files; ENC.PMT and PERMIT.TXT. All Chart Permit files contain permits for all the
licensed ENCs.
Insert the Permit disk, or other permit media, into the ECDIS by following the procedures supplied by the
ECDIS manufacturer.
Loading Base Charts
All subscribers to the Admiralty Vector Chart Service are automatically supplied with all available AVCS Base
disks, but you only need to load the Base disks that contain data you have licensed (please refer to your
Schedule A or e-Navigator for this information). Certain ECDIS require the Base disks to be loaded in the
correct numerical order, therefore users who have licensed charts from multiple Base disks must
always ensure that they are loaded in numerical order (i.e. Base disk 1 ahead of Base disk 2). If Base
disks are loaded in the wrong order, you risk having to uninstall all pre-loaded ENC data before being able to
load the base data correctly.
It may not be necessary to load all of the Base disks provided in your Media Pack. Your Schedule A or
e-Navigator will list the Base CD required for each ENC that you have purchased. Normally only these disks
need to be loaded.
Most ECDIS will allow you to choose whether to load all licensed charts or just those of your choice. When
initially loading charts, you should be aware that the process can take some time because the ECDIS has to
reformat the charts into an equipment specific format called System ENC (SENC) before use. If you require
quick access to the charts then it is suggested that you load only those needed to meet your immediate
requirement.
Please note that between re-issues of Base disks, all newly available charts are provided via the Update CD.
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Loading Updates from the Base disks
The Base disks may also contain updates. Some ECDIS systems require you to run an ‘Update ENC’
process as a separate procedure from the installation described above.
If you do not update from the Base disks first, subsequent updates from Update CDs may not load as they
will be out of sequence.
Loading the latest Update CD
Once all applicable Base disks have been loaded it is important to also load the latest Update CD to ensure
that all ENCs are fully up to date.
Admiralty Vector Chart Service Update CDs contain cumulative information. If you receive more than one
AVCS Update CD at the same time, you only need to load the most recent one. Having loaded the Base
disks and Update CDs, the ECDIS system will then display the latest chart information available.
Maintaining the Chart Outfit
New Chart Permits
You will automatically be issued with all necessary Chart Permits to provide access to newly available or
replaced ENCs within your licensed AVCS Folios and Units. Please ensure that you load new Chart Permits
before installing the Update CD to ensure your ECDIS has the capability to use the charts from the latest
CDs.
If you are updating from the Update CD (rather than over the Internet) you will receive replacement Chart
Permit files before you receive the corresponding Update CD. It is important that you do not install these
unless you have the corresponding Update CD for the same week. Failure to follow this advice could render
some of the installed ENC unavailable for use in the ECDIS. The only exception to this rule is if additional
coverage is required in cases of emergencies or changes to a planned route.
Update CDs
The Admiralty Vector Chart Service Update CD is issued weekly containing all the latest ‘Notice to Mariners’
corrections, New Editions and any New Charts issued. Updates are also available by e-mail and over the
Internet using Admiralty e-Navigator or the Admiralty Updating Service.
On receipt of the Update CDs you should load the new data using the update procedure specified in your
ECDIS manual. The process should be automatic, but as required by the ECDIS specifications you will be
asked by the ECDIS to accept the updates. Again, if you receive more than one Admiralty Vector Chart
Service Update CD at the same time, you only need to use the most recent one because they are
cumulative.
If replacement AVCS Base disks have been issued, containing New Editions or updates of cells, subsequent
Update CDs cannot be installed until the Base disks have been installed.
It is possible that your ECDIS will occasionally report warnings or errors during the update process. Whilst it
is not possible to be definitive in this matter, users are advised that a warning can be accepted as being very
unlikely to corrupt data already loaded, but an error should be treated more seriously and the chart should
only be used with caution since it may not reflect the latest Notices to Mariners information. Users should
notify the UKHO Customer Services Team (see contact details inside front cover) if their ECDIS system
reports errors on loading of charts or updates.
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NB: Stored Routes and Updates
Updates applied to the ECDIS may affect previously stored routes. It is important to check the effect of any
updates on a stored route prior to its use. ECDIS is able to automatically check route safety where licensed
AVCS data is available.
Re-Issued Base disks
The UKHO periodically re-issue Base disks (CD or DVD) in order to integrate newly available Base data that
is temporarily held on the Update CD. When this happens, all currently available Base disks are issued
simultaneously. All new editions and updates are also included on the replacement AVCS Base disks at this
time; therefore no accompanying Update CD will be issued in a week when this occurs.
On receipt of re-issued AVCS Base disks you only need to run an update routine; there is no need to reload
all charts.
README.TXT File
The AVCS Base and Update disks contain a ‘README.TXT’ file which includes important safety information
that should be read before using the service. For example it includes a caution concerning ENCs derived
from charts which are not on WGS84 or a compatible datum.
The file is located in the ENC_ROOT folder on each disk and contains the following information:
• Specific charting practices of some ENC producers which may be significant to navigation.
• Specific updating practices of some ENC producers such as delays between the issue of paper NMs and
ENC updates.
• Identified overlaps between ENCs which may cause problems in display systems.
• ENCs which have been withdrawn from service for any reason and which should not be used (permits
will not normally be issued for these ENCs).
• Specific licence and disclaimer text required by some ENC producers.
The README.TXT file is updated every week and changes are highlighted in a ‘Latest Corrections’ section
at the beginning. The file should be read as part of the weekly ENC update process to ensure that all
relevant changes are understood.
Cancelled ENCs
Periodically ENCs are cancelled as part of the continuous maintenance of ENC coverage worldwide.
Normally cancelled ENCs are automatically replaced and you will experience no loss of coverage in your
ECDIS.
When an Update CD containing cancelled ENCs is loaded into ECDIS, some systems will ask the user
whether or not to remove (or delete) the cancelled ENCs from the SENC (system database). It is strongly
recommended that you choose to remove the cancelled ENCs from the SENC because cancelled ENCs are
no longer updated.
Failure to remove cancelled ENCs from the SENC may result in the ECDIS displaying out of date data
in preference to more up to date data.
Licence Expiry
Once the licensed period for an ENC Unit or Folio has ended, the ECDIS system will prevent the loading of
further updates until the licence for the ENC Unit or Folio is renewed. You will be able to continue to view all
ENCs and updates that were loaded prior to licence expiry. The expiry date is shown on the Schedule A
supplied at the time of purchase and in e-Navigator.
AVCS must be kept up-to-date to meet IMO SOLAS requirements. ENCs beyond their expiry date will not be
updated and may not meet chart carriage requirements.
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Adding Chart Coverage
Additional AVCS Folios and Units may be purchased during the subscription period through your chosen
Admiralty Chart Agent who will supply new Chart Permits to ‘unlock’ the newly added data. These permit files
are cumulative so as well as unlocking the new coverage they will also hold the permits necessary to unlock
all your existing coverage.
Support
Support for all of your Admiralty products is available from your Admiralty Chart Agent.
Support from the UKHO is provided through the Customer Services Team. All enquiries are logged on
receipt, allocated a unique reference number and monitored through to closure. The Customer Services
Team can be contacted with any question relating to any Admiralty product. Contact details are on the last
page of this guide.
Emergency Chart Permit Generation
Where a vessel is diverted for commercial reasons an order can be raised through your supplier. Your
supplier will receive the permits within 10 minutes of placing the order with the UKHO and these can then be
forwarded on to you by arrangement with your supplier.
In certain circumstances it may be necessary for a vessel to get access to an AVCS chart at very short
notice, for instance if she has to divert her route due to a medical or safety emergency. In these emergency
circumstances, individual AVCS Chart Permits can be obtained from the UKHO 24 hours a day, 365 days a
year. These Chart Permits can be transmitted direct to the vessel by email wherever possible, by fax, or
simply by reading the characters out over the telephone or radio. Each Chart Permit consists of 64
characters.
To obtain an AVCS Chart Permit please contact the UKHO Customer Services Team. Please quote your
vessel name, the User Permit Number of your ECDIS system and the cell number(s) required.
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AVCS Service Details
About AVCS
ENC Cell Usage Bands and Identifiers
AVCS is an ENC-based service sold as Units and in convenient and cost-effective Folios. Each Transit,
Regional and Port Folio includes selected ENC cells, and is displayed in exactly the same way.
The digitised vector data in an ENC records all the relevant chart features such as coastline, buoys, lights,
etc. These features, including their associated attributes and attribute values are held in a database that
allows them to be selectively displayed and queried. This provides the potential to manipulate the chart
image displayed on screen.
Each ENC has an 8-character identifier. The first two characters indicate the producer nation (e.g. GB for a
UK produced cell, NL for a Netherlands cell, etc), the third character indicates the ‘usage band’ into which
the cell falls and the last 5 characters are used as the unique identifier for that ENC.
The usage band designator indicates the intended navigational purpose of the ENC and will take one of the
following values:
1 Overview
2 General
3 Coastal
4 Approach
5 Harbour
6 Berthing
Therefore, GB500005 is a UK produced ENC cell in the harbour usage band.
Validation
Comprehensive validation checks are run on all ENCs before they are released in the Admiralty Vector Chart
Service to ensure consistency with IHO standards. This minimises the chances of errors or warnings being
displayed on the ECDIS during loading caused by minor interpretational differences in the standard between
ENC producers and ECDIS manufacturers.
If you do experience any problems with data quality, you should contact your Admiralty Distributor or the
UKHO Customer Services Team so that the situation can be promptly investigated.
Authenticity
It is important to ensure that the charts loaded into your ECDIS have come from an authorised source,
especially if you are using ENCs as your primary source of navigational information. All ECDIS capable of
using the IHO S-63 Data Protection Scheme automatically verify this by authenticating the digital certificate
stored on the system against the signature file associated with each cell loaded.
Newer ECDIS (post 2003) often come with the IHO digital certificate pre-installed as the IHO is the Scheme
Administrator (SA) for the S-63 ENC Data Protection Scheme. The UKHO is a certified subscriber to this
scheme. However, to ensure compatibility with older ECDIS, it does not use the IHO Public Key. AVCS
ENCs are currently authenticated against the PRIMAR Public Key because some older ECDIS are not
compatible with the IHO Public Key.
Updates
The Admiralty Vector Chart Service supplies the latest updates issued by the chart producer. These updates
may or may not be synchronised with Notices to Mariners produced for their national paper chart series. UK
produced ENCs are maintained for Notices to Mariners in line with the Admiralty paper chart series.
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Admiralty Information Overlay
What is the Admiralty Information Overlay?
The Admiralty Information Overlay is a digital dataset that is designed to be displayed over ENCs in ECDIS
and other chart display systems to provide additional information to the navigator.
The Admiralty Information Overlay contains all Admiralty Temporary & Preliminary Notices to Mariners (T&P
NMs) and provides additional preliminary information that is specific to ENCs, such as reported navigational
hazards that have been incorporated on paper charts but have not yet been included in ENCs.
The Overlay gives seafarers an easy way to view the information they need, in addition to the standard chart,
to navigate safely and compliantly. The Overlay makes passage planning simpler and safer by clearly
showing where important Temporary or Preliminary changes may impact a voyage. It also gives seafarers
the same consistent picture of the maritime environment on their ECDIS as they have always had with the
Admiralty paper chart.
The Overlay includes all Admiralty T&P NMs in force worldwide and additional information that relates
specifically to ENCs, published as ENC Preliminary NMs (EP NMs).
Installing the Admiralty Information Overlay
Compatible Equipment
The Overlay can be displayed on compatible ECDIS equipment and also in Admiralty e-Navigator Planning
Station. Please see the UKHO website at www.ukho.gov.uk/AVCS for an up to date list of compatible
equipment, or consult your ECDIS supplier. Most ECDIS equipment installed prior to 2011 will require an
upgrade before it will be able to display the Overlay.
Installing Overlay Permits
The Overlay data is protected in the same way as ENCs and requires a permit to unlock the data. Please
notify your Admiralty Chart Agent if you wish to use the Overlay on any compatible display system so that the
Overlay permit can be added to the Chart Permit files issued to you.
The Overlay permit will be loaded at the same time as your ENC permits when the Chart Permit files are
loaded (see ‘Loading Charts for the First Time’ above).
When the Overlay is added to your AVCS licence the Overlay permit will be added to the Chart Permit files
issued for all ECDIS registered on the licence. Older ECDIS that do not recognise the Overlay may display a
message when attempting to load the Overlay permit. This message will not prevent the ENC permits
loading correctly.
Installing Overlay Data
The Overlay data is provided on a single weekly CD that contains both base data and all updates up to the
date of issue. Therefore only the latest CD is required for installation and all others can be discarded.
The Overlay data is loaded into the display system in the same way as ENC data. Note that some display
systems may require you to run an ‘Update ENC’ process after loading the base data to ensure that all
updates on the disk are also applied.
Updating the Overlay
Updates to the Overlay are issued weekly on CD, along with the weekly AVCS Update CD, and are also
available over the Internet through e-Navigator. Updates on CD should be loaded in the same way as
loading ENC updates (see ‘Maintaining the Chart Outfit’ in the AVCS User Guide).
The data volume in each weekly update is normally small. However it is necessary to issue a New Edition of
the Overlay every 6 months, which consolidates all update data into a base data set. This New Edition may
be over a hundred megabytes in size which will make it impractical for most users to download over the
Internet and an Admiralty Information Overlay CD should be used.
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When an Overlay new edition is issued (see above), the new edition must be installed before any further
updates can be applied. For users who normally update over the Internet this means that an Overlay update
CD will need to be installed before further Internet updates can be applied.
Using the Admiralty Information Overlay
Displaying the Overlay
The Overlay is designed to be displayed on top of a standard ECDIS chart display and can be switched on
and off without changing the underlying chart.
Only those features relevant to the chart in use are displayed. As the user zooms in or out, the ECDIS will
automatically select charts of a suitable scale and the Overlay features relevant to the selected charts will be
displayed. For example, a Temporary NM that applies only to a large scale chart will not be displayed when
smaller scale charts of the same area are being used.
T&P NMs
All Admiralty T&P NMs that are in force are included in the Overlay. Each NM is displayed as a simple red
polygon (usually rectangular) with red hatched fill which indicates the area affected by the NM. Each NM
carries the same NM number that is used in the Admiralty Notices to Mariners Bulletin.
The full text of the NM is included as an associated text file which can be displayed by selecting the
‘Temporary Notice to Mariners’ or ‘Preliminary Notice to Mariners’ feature in the ECDIS Pick Report. Any
associated diagrams can also be viewed through the Pick Report.
Figure 4 Preliminary (P) NM
EP NMs
ENC P (EP) NMs contain additional information that is specific to ENCs and cannot be published as a
standard Admiralty T&P NM. These NMs are displayed in the same way as T&P NMs, as a simple red
polygon (usually rectangular) with red hatched fill which indicates the area affected by the NM. Each NM is
allocated a unique EP NM number.
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The full text of the NM can be viewed in the ECDIS Pick Report against the Information attribute. Where
additional information is needed to explain the NM an associated picture file displays an image showing the
ENC superimposed over the current paper chart information.
Figure 5 ENC Preliminary (EP) NM
‘No Overlay’ Feature
Where there is no equivalent scale Admiralty paper chart, the UKHO does not have any additional
information and the Overlay shows a ‘No Overlay’ feature. This feature is displayed as a grey polygon with a
grey hatched fill indicating the area where there is no overlay information.
Additional information, such as local T&P NMs, may be available in these areas from other sources.
When navigating in these areas, seafarers should ensure that all appropriate sources of information
have been consulted.
Using the Admiralty Information Overlay in the Navigation Process
The Admiralty Information Overlay contains additional information that is considered navigationally significant
and may affect your voyage. This information should be referred to when planning your passage and may
also be temporarily displayed during route monitoring.
When planning your passage it is normal to review all charts (and therefore ENCs) that are expected to be
used on the passage. When these charts are reviewed the Overlay should be turned on and any features
that could affect the planned route should be investigated. Those features that are significant for the
planned passage should be marked using Mariner’s Navigation Objects, which can be displayed by the
ECDIS when navigating. Sufficient information should be attached to the Mariner’s Navigation Objects to
inform the navigator of the action to be taken when they are encountered on passage.
If the navigational ECDIS is capable of displaying the Overlay, Overlay information may temporarily be
displayed when navigating. To avoid too much information obscuring the chart display the Overlay should
normally be turned off and should only be turned on for brief periods when required for reference. Therefore
Mariner’s Navigation Objects should be used to draw attention to relevant Overlay features when the Overlay
is turned off.
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Chart Carriage Regulations
Flag State Acceptance of ECDIS
SOLAS regulations were amended in 2000 to specifically allow the use of ECDIS to meet carriage
requirement in place of paper charts.
“All ships irrespective of size shall have 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 sub paragraph.”
IMO SOLAS Chapter V, Regulation 19, 2.1.4
As yet, not all nations have adopted the amended regulations into their own national legislation nor have
they made clear their acceptance of ECDIS. For this reason ship owners and mariners should consult their
Flag State authority for guidance on meeting SOLAS obligations with ECDIS.
To meet chart carriage requirements the ECDIS must be type approved, have a suitable back up that can
take over in event of failure of the primary system and be using ENCs. As AVCS is an ENC-based service,
when displayed in a type-approved ECDIS with an appropriate backup, it may be used for primary navigation
where flag state approval exists (SOLAS V reg 19 2.1.4) and replace the paper chart.
Mandatory Carriage of ECDIS
In 2009, the Maritime Safety Committee (MSC) of the IMO agreed to the formal adoption of a mandatory
carriage requirement for ECDIS. The changes to SOLAS Regulation V19 mean that all large passenger,
tanker and cargo ships will be obliged to fit ECDIS on a rolling timetable that begins in July 2012.
Port State Control
It is normal for any Port State inspection to accept the vessel’s Flag State implementation of SOLAS
regulations; the vessel should carry documentation to show compliance to their Flag State requirements.
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Using Electronic Charts in ECDIS
Your ECDIS user manual will outline many useful system features and functions that can be used to assist
you in navigating your vessel. However, using electronic charts, especially for the first time, presents the
mariner with many new and important issues that need to be taken into consideration if the highest levels of
vessel safety are to be maintained. In the following section of this guide we have outlined some of these
issues and we urge you to take these into consideration when using electronic charts provided in the AVCS.
Admiralty publication NP100, The Mariner’s Handbook, contains detailed guidance on the issues outlined
below, including information about the safe use of charts in general and ENCs.
Training
It is recommended that users undertake both generic training in the use of electronic chart systems and
charts as well as type specific ECDIS training for the system to be used. Training in the use of the advanced
voyage planning and monitoring facilities that these systems provide will ensure you can take maximum
advantage of the benefits of electronic charts
Chart Accuracy
The ECDIS is a powerful navigational tool. However its usefulness is limited by the quality of the chart data
that it is using. Most ENCs are derived from paper charts; therefore, the accuracy of the chart displayed on
the ECDIS will generally be no better than that of the equivalent paper chart, both in terms of positional
accuracy and hydrographic information content.
It should be remembered that the positional accuracy of features on charts based on old surveys may not be
as good as the positions that can be obtained from GPS; this fact should be taken into account when
determining suitable clearance distances from charted features.
Source Data Quality
Source data accuracy is shown on the face of an ENC using symbols. There are 5 ‘Zone of Confidence’
categories, each depicted by ‘stars’ within a triangle outline (6 stars being the best). The confidence rating
refers to the level of confidence that the producer has in the accuracy of the source data from which the chart
is compiled. Due to the difficulty of allocating a zone of confidence category, especially where derived from a
paper chart, a 6th ‘un-assessed’ category (a ‘U’ within an ovoid outline) is commonly used.
Chart Display Scale
Just like paper charts, ENCs are compiled at scales suited to their intended use, taking account of all
available source material. For this reason they should only be used for navigation at, or near, their
compilation scale.
The majority of ECDIS systems incorporate a zoom function that allows the user to enlarge or reduce the
scale of the displayed image. This function can be useful, for instance, for enlarging complex areas for the
purposes of clarity. However, navigating using a scale significantly different from the compilation scale is
potentially dangerous as it can give a false impression of distances.
For this reason, ECDIS systems give a visual warning when charts are ’over-zoomed’. This is a graphical
warning appearing as vertical bars on the display. Some ECDIS also display a prominent warning message
somewhere in the viewer stating that the cell is being viewed at either “OVERSCALE” or “UNDERSCALE”.
Where a greater or lesser level of chart detail is required, a larger or smaller scale chart should be selected
for use.
Chart Display
When navigating using ECDIS, users can select the amount of detail that is displayed, thereby reducing the
amount of visible charted detail on screen. There are three common display modes; ‘base’, ‘standard’ and
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‘all’. The minimum level of detail that is allowed to be displayed is contained in the ’base’ display; this is not
intended to be sufficient for safe navigation.
ECDIS generates warnings based on the full chart database not just from the details displayed.
Scale Minimum (SCAMIN)
The SCAMIN attribute defines the minimum (smallest) scale at which particular features in an ENC are
displayed in an ECDIS. It is set to a smaller scale than the compilation scale, which is the scale at which the
ENC is intended to be used for navigation. It is a very powerful attribute that is set against particular features
with the aim of reducing ECDIS screen clutter when zooming out.
The IHO has recommended best practice for setting SCAMIN, which has been accepted by the majority of
Hydrographic Offices. This may take some time to implement and, until implementation is complete, there
may be instances of display such as shown in Figure 6. In this case SCAMIN has been set in the eastern
ENC cell, but not in the western ENC cell.
Figure 6 SCAMIN set in the E ENC cell but not in the W ENC cell
Whilst this view can be disconcerting it remains safe to use because the information does exist in the eastern
ENC cell and will be continuously monitored by the ECDIS.
Contour Intervals
Adjoining paper charts often use depth contours of different values and these have been used by mariners
for many years without particular problems. However, when different contour intervals are used in adjoining
ENC cells an odd stepping effect can result when the ECDIS-generated safety contour crosses from one cell
to the next. This problem is more obvious in ENCs because of the seamless nature of the electronic chart.
A best practice for encoding contour values has been issued by the IHO, but it may be some time before this
is implemented universally owing to the varied sources from which ENCs are created.
Overlapping ENCs
There are instances where ENC data from different suppliers overlaps within the same Usage Band.
Mariners should be aware that where such overlapping data conflicts, different ECDIS systems handle and
display the data in different ways, and that an ECDIS might display data that hasn’t been updated in
preference to data which has. In some cases, two overlapping chart cells may be displayed at the same
time. The UKHO makes every effort to minimise the impact of overlapping data in AVCS but is not permitted
to modify ENC data from the hydrographic authorities of other nations.
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Use of other Chart Formats
As well as being able to use official S-57 data, many ECDIS systems provide the facility to use other types of
electronic chart. Where other chart data is used in the ECDIS in combination with Admiralty Vector Chart
Service charts, users should exercise caution as this other data may not be produced to the same standard
or updated to the same date.
Settings and Alarms
It is vitally important that safety values, particularly relating to depth contours and ships draft, are
correctly set in the ECDIS equipment. Failure to do so could lead the mariner to believe that, due to
the absence of an alarm, he is in safe water. Similarly, if erroneously set in the opposite sense, the
mariner may restrict himself unnecessarily when more safe water is available than indicated by the
display.
The mariner should always set safety contours and safety depths. In both cases the system will highlight the
selected contours and depths. If safety contours are not selected, the system will display a safety contour of
30m by default.
A look ahead range, expressed either as a distance or a time should also be set by the mariner to control
how far in advance an alert is given before a distance limit is crossed. The same look ahead range should
be set for approaching boundaries of prohibited areas, areas where special conditions apply, and crossing a
safety contour or proximity to danger. This range should never be set to zero.
In some situations, such as in particularly confined waterways, it may be necessary to reduce the look ahead
range to prevent the excessive sounding of alarms. When reducing the look ahead range it is important to
ensure that all ECDIS users are aware of the altered settings and to return the settings to their normal values
as soon as possible.
Procedures
ECDIS linked to GPS, radar and other navigation devices is a powerful aid to navigation, providing
assistance for quick and sound decision making; however it should not be used in isolation to make
navigational decisions.
Visual observation of the world beyond the bridge windows remains vital for safe navigation. By providing
continuous display of own vessel position and radar targets ECDIS can provide additional opportunity for the
watch keeper to keep lookout
It remains essential to monitor the correct operation of all electronic equipment. Traditional relative
navigation techniques (e.g. visual fixing or radar range and bearing) should be employed to confirm that
correct vessel position is shown on the ECDIS.
It is important to ensure that all of the latest updates are loaded onto the system, and whenever possible, it is
preferable to load available updates before you commence your voyage. Please note that loading and
updating can take some time.
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Use of ECDIS with Global Positioning Systems (GPS)
Accuracy and Availability
GPS is capable of horizontal positioning accurate to approximately ±33m for 95% of the time. DGPS (a
refinement of GPS) allows a typical accuracy of ±5–10m. It should be remembered that many of the surveys
on which both paper and modern electronic charts are based were carried out long before GPS was
available. Thus the accuracy of charted detail will in many cases not be to the same order of accuracy as is
provided by GPS. This fact should be considered in determining which scale chart to use, and what are
suitable tolerances when making navigational decisions.
The mariner is encouraged to employ alternative means to monitor GPS positional accuracy and to have an
independent means of position fixing on the ECDIS so as to ensure continued safe navigation if GPS is
subject to accuracy or availability problems.
GPS Reference Datum and Chart Datums
GPS is based on the World Geodetic System 1984 (WGS84) datum. However positions on many original
surveys have been established by taking astronomical observations. Historically, the survey of each
geographical area might have been based on different established datum, and accordingly charts worldwide
have been drawn on a variety of datums. The relationship between the positions of features surveyed on
different datums is still not necessarily known. This means that any point on the Earth's surface may have a
different latitude and longitude depending on the local datum to which the position is referred.
For this reason GPS positions for charted objects can be very different from their local datum positions; this
difference is known as the datum shift.
Further information on GPS and other satellite navigation systems can be found in the Admiralty List of
Radio Signals Volume 2 (NP282)
GPS Receiver Settings
Older GPS receivers are not able to provide Datum information via the NMEA interface to ECDIS and some
earlier ECDIS systems may not recognize this information if it is provided. It is therefore strongly
recommended that, when used with ECDIS, GPS receivers are set to output positions in WGS84 Datum.
If the GPS is set to provide positions in other than WGS84 datum then it is possible that the ECDIS may
misinterpret the data received and positions may be incorrectly displayed.
Route Planning and Datums
Positions stored for routes and / or overlay information may be recorded as local datum positions. If the route
is later plotted on a chart having a different datum, the route may not plot correctly. Care should be taken
when displaying such data on a chart other than the one on which it was created or where routes are
transferred between systems.
Use of ECDIS with Radar
Many ECDIS systems have the capability to overlay both raw radar video and / or ARPA (Automated Radar
Plotting Aid) targets onto the display. Where the full radar image is used it is possible that charted
information may be obscured. Superimposition of the full radar image may cause unacceptable cluttering of
detail on some charts.
ARPA Targets
The superimposition of ARPA targets on the ECDIS display allows the rapid assessment of the possible
actions of targets with respect to shoal water, traffic separation schemes etc. The Radar should remain the
primary tool for collision avoidance; ECDIS should only act as an aid to possible target intentions.
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Using Radar as a check on vessel position
A convenient means to monitor correct referencing of vessel position to chart is to choose a charted radar
conspicuous feature and to select this as an ARPA target which is displayed on the chart. If the target
remains located over the charted position of the feature this is a good indication that systems are functioning
as expected.
Where the ECDIS allows the display of raw video over the chart a comparison of charted coastline with the
radar image can be used in the same way; however care should be exercised as the apparent RADAR
coastline can vary according to the nature of coastline and height of tide.
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Troubleshooting / Problem Solving
Should you experience problems when loading data into your ECDIS, you may find it difficult to determine
exactly which element of your system is at fault. Where one of the standard error messages shown below is
encountered then you should report this to your Admiralty Distributor or contact the UKHO Customer
Services Team. If the fault appears to be hardware related (eg failure of a floppy disk or CD drive) then we
advise you to contact your ECDIS system supplier.
When reporting a chart related problem it is useful if you can provide the following details:
• Admiralty Vector Chart Service licence number
• ECDIS system being used (especially if you have more than one system on board)
• The date (or week number) of the latest disks held on the vessel
• The issue date of the latest Chart Permits held. If the problem appears to be related to the permits it is
best to send a copy of the latest Chart Permits held by email if this is possible.
• Any error messages displayed on the ECDIS
Whilst the wording of displayed error messages may vary from ECDIS to ECDIS the error codes are
constant.
Errors
Standard Error codes when loading AVCS
Error messages likely to be displayed in an ECDIS
SSE 03 Certificate is invalid (Authentication failure)
SSE 04 Format of Certificate is incorrect (Authentication failure)
SSE 05 SA Digital Certificate file is not available (Authentication failure)
SSE 06 SA Digital Certificate is invalid (Authentication failure)
SSE 07 Certificate file is not available (Authentication failure)
SSE 08 Format of Private Key is incorrect (Authentication failure)
SSE 09 Signature is invalid (Authentication failure)
SSE 10 Files are different (check after decryption)
SSE 11 Cell Permit file not found (Decryption failure)
SSE 12 Cell Permit format is incorrect (Decryption failure)
SSE 13 Cell Permit is invalid (checksum [CRC] is incorrect / decryption failure)
SSE 14 Incorrect system date
SSE 15 Subscription licence has expired
SSE 16 ENC CRC value is incorrect
Codes 03 to 09 relate to the ECDIS check of the authenticity of the disks being loaded.
Codes 11 to 13 relate to the permits supplied
Codes 14 and 15 relate to checks on licence validity
Codes 10 and 16 relate to checks carried out on the consistency of the ENC data.
Decryption Failure
This is normally due to the Chart Permit available not being compatible with the edition number of the chart
being loaded. Check that the latest Chart Permit files have been loaded. If the problem is not resolved by
reloading the Chart Permits then contact the UKHO Customer Services Team. Please inform them of the
latest Base / Update being used, any error messages displayed and forward a copy of the PERMIT.TXT file
from the permit disk if using email.
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Conversion Errors
When charts are loaded into an ECDIS they are converted from the standard format they are supplied in
(S-57) to the systems specific format of the ECDIS being used (the System ENC – SENC). Conversion
errors are reported when the ECDIS is unable to interpret the detailed information within the chart during the
conversion process.
Data being supplied within the Admiralty Vector Chart Service has been validated to very high standards and
the number of errors being reported should be low. However the ENC data standard (S-57) is extremely
complex and in some circumstances it is possible for the ECDIS supplier and ENC producer to have used
subtly different interpretations of the standard and this can result in a warning message being displayed on
ECDIS.
When loading charts the ECDIS could report three error conditions:
1. The ECDIS is unable to load the chart or Update at all. This is very uncommon; please report this
problem to the UKHO Customer Services Team.
2. The ECDIS loads the chart or Update and reports an error. This is not common; users should use the
chart with caution and report the error to the UKHO Customer Services Team.
3. The ECDIS loads the chart or Update and reports a warning. This is quite common on some ECDIS
systems and reflects minor interpretational differences of the S-57 standard. We are not aware of any
evidence that the correct operation of the chart in the ECDIS is affected in these cases.
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Copyright Information
The Admiralty Vector Chart Service is derived from Crown Copyright information and information supplied by
other organisations. Except as provided in the User Licence, no part of the Admiralty Vector Chart Service
may be sold, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical,
photocopying, recording or otherwise without the express permission of the United Kingdom Hydrographic
Office, Admiralty Way, Taunton, Somerset, United Kingdom, TA1 2DN.
All ENCs included in the Admiralty Vector Chart Service are issued by or on the authority of governmentauthorised
Hydrographic Offices. Each country is responsible for producing ENCs of its own waters, which
must be updated systematically with all safety-critical information and be fully compliant with the International
Hydrographic Organisation’s (IHO’s) S-57 ENC product specification. Therefore each ENC producing nation
carries the liability for its own data as supplied in this service.
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Annexes
Table of Figures
Figure 1 AVCS Transit Folios ............................................................................................................................ 3
Figure 2 AVCS Regional Folios......................................................................................................................... 4
Figure 3 AVCS Port Folios ................................................................................................................................ 5
Figure 4 Preliminary (P) NM ............................................................................................................................ 14
Figure 5 ENC Preliminary (EP) NM ................................................................................................................. 15
Figure 6 SCAMIN set in the E ENC cell but not in the W ENC cell................................................................. 18
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Glossary
ARPA
ECDIS
ECS
ENC
GPS / DGPS
IC-ENC
IHO
IMO
POSACC
PRIMAR
RENC
RNC
Automated Radar Plotting Aid – a radar-based system that can create tracks from radar contacts,
calculating course, speed and closest point of approach.
Electronic Chart Display and Information System – a specific term to denote equipment that, when
used in conjunction with up-to-date ENCs and adequate backup arrangements, may be used for
primary navigation.
Electronic Chart System – a generic term for any digital navigational chart display system that does
not conform to the definition of an ECDIS, or to describe the mode of operation when an ECDIS is
used with unofficial charts. In both cases the ECS cannot be used for primary navigation.
Electronic Navigational Chart – an official, Government produced digital chart, manufactured to the
IHO / IMO approved standards. When operated on IMO type-approved ECDIS equipment, ENCs
may be used for primary navigation.
Global Positioning System / Differential Global Positioning System
International Centre for ENCs – an association of national hydrographic organisations working
together to harmonise the production and distribution of ENCs. IC-ENC is one of 2 principal RENCs
(PRIMAR is the other). IC-ENC is operated by the UKHO on behalf of its member nations.
International Hydrographic Organisation
International Maritime Organisation
Positional Accuracy attribute used to encode the level of accuracy of positions of features in an ENC.
One of 2 principal RENCs (the other is IC-ENC), operated by the Norwegian Hydrographic Service on
behalf of its member nations.
Regional ENC Co-ordinating Centre – an organisation established by IHO members who cooperate
to guarantee a consistent level of high quality data, and to bring about coordinated services with
official ENCs and updates to them.
Raster Navigational Chart – a raster-scanned (as opposed to vectorised) digital facsimilie of a paper
chart. Exceptionally, Government produced RNCs may be used for primary navigation, although an
adequate paper chart backup must be carried.
S-52 Mandatory IHO standard that defines the appearance of ENCs on an ECDIS screen.
S-57 Mandatory IHO standard that defines the way chart information is encoded in an ENC.
S-63
SCAMIN
Schedule A
SENC
SOLAS
UKHO
Unofficial charts
WGS84
IHO standard for the encryption and copy protection of ENCs. All ECDIS equipment must accept
S-63 ENCs. Manufacturers may optionally add SENC capability.
Scale Minimum attribute used to automatically de-clutter the ECDIS screen when zooming out.
Features that have been selected by the ENC producer to be removed from the display will not be
shown when the display scale is smaller (zoomed out further) than the SCAMIN value.
A listing of all chart holdings purchased through a single transaction (weekly updates will only show
changes to those holdings)
System ENC – a manufacturer-specific data storage format for ENCs (contrast with S-63) that
encrypts and copy protects ENCs and may be used for distribution.
IMO Safety of Life at Sea Convention. Chapter V Safety of Navigation governs the carriage
requirements for navigational information, including charts.
United Kingdom Hydrographic Office
A generic term to describe all digital charts that do not conform to the specifications for an ENC and
may not therefore be used for primary navigation.
World Geodetic System, 1984 datum – the horizontal positioning system used by GPS. All ENCs are
referred to WGS84. When the source information used to create the ENCs has been shifted to
WGS84 datum, the POSACC attribute may be used to encode the size of any positional error
introduced. Care must be exercised when plotting information referred to another horizontal datum
on an ENC.
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Feedback
The UKHO welcomes customer comments, if you would like to provide any feedback, please forward any
comments via your Admiralty Distributor or directly to the UKHO Customer Services Team. Contact details
are on the last page of this guide.
Contact Details
Company Contact
If your company has a specific policy for obtaining support on IT and navigational systems, please enter
details here, with contact details for the Support department:
ECDIS Manufacturer
Support Hours (Time Zone):
Web:
Telephone:
Facsimile:
Email:
Contact:
Chart Agent
Support Hours (Time Zone):
Web:
Telephone:
Facsimile:
Email:
Contact:
UKHO
Support Hours (Time Zone):
24hrs
Web: www.ukho.gov.uk/Support
Telephone: +44 (0)1823 723366
Facsimile: +44 (0)1823 330561
Email: customerservices@ukho.gov.uk
Contact: UKHO
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