ECDIS Simplified

                 

 ECDIS - Electronic Chart Display and Informatin System 

EGS - Electronic Chart System

unofficial charts 

not approved hardware 

can not be used as an aid to navigation

ECDIS - Electronic Chart Display and Information System

official charts 

type approved software 

can be used for primary navigation

AIO - Admiralty Information Overlay 

contains all admiralty Temporary and Preliminary notice to mariners

AIO is a world wide digital dataset ,that is designed to be displayed over ENCs in ECDIS

to provide additional information during passage planning 

AIO is refreshed every week as part of the AVCS weekly update and is issued on disc and by download

some back bridge applications allow the vessel to download the updates each week.

AVCS - Admiralty vector Chart Service 

is the world wide official digital maritime chart service with 15,800 official electronic navigational charts to navigate safely and efficiently whilst meeting flag and port state requirements.

RCDS - Raster Chart Display System

is a navigation information system displaying raster navigation charts with positional information from navigation sensors to assist in route planning and route monitoring 

and if required display additional navigation related information

under IMO performance standard the following alarms and indications are required for ECDIS in operating in RCDS mode

                  deviation from route

                  position system failure

                  approach to critical point

                  malfunction of RCDS mode

                  large scale RNC available for ships position

ECDIS 

is a navigation information system which with adequate backup arrangements can be accepted as complying with the upto date charts required by SOLAS.

by displaying selected information from a system electronic navigation chart with positional information from navigation sensors to assist the mariner in route planning and monitoring.

Dual Fuel system 

is one that operates as an ECDIS and RCDS ,depending on the type of chart data in use .ECDIS has two official modes of operation

1) ECDIS mode 

    in areas where ENC coverage is available ,the ECDIS system utilizes the official data and is said to        be operating in the ECDIS mode.

2) RCDS mode 

    there still are areas where official data is not available and ENCs not published .however in such            areas instead of ENCs  RNCs are used . at such time RCDS mode is said to be operation.

    when operating RCDS mode an appropriate port folio of up to date paper charts should be carried            onboard.

Navigation Purpose

specific purpose for which an ENC has been complied 

there are six purposes ( usage bands)

                              1) berthing

                              2) harbor

                              3) approach

                              4) coastal

                              5) general

                              6) overview    

  

RENC -  Regional ENC Cordinating Centre 

is an organisation where IHO member states have established cooperation among each other to guarantee a world wide consistent level of high quality data and for bringing coordinated service with official ENCs and updates to them.

there are two RENCs

                            1. PRIMAR - Norway

                            2. IC - ENC - United Kingdom & Australia

issuing authority for official ENCs and official updates.

SENC - System Electronic Navigation Charts

means a database in the manufactures internal ECDIS format 

each manufacture has different SENC

resulting from the loss less transformation of the entire ENC contents and its updates

it is the database that is accessed by ECDIS for display generation 

this also contains informations added by the mariner and information from other source 

all ECDIS manufactures have different graphic layouts and hardware 

but one thing they all have in common ,they all read and use S-57 ENC chart format 

and transfer it into their own SENC format .

it means when ENC chart is loaded into the system it becomes a SENC chart.

Advantages of ECDIS over paper chart 

real time fixing 

ease of passage planning

navigational info at a glance 

alarms and indications to highlight danger

ease of chart correction

zooming facility 

more accurate ETA can be worked out

overall enhance safety of navigation

Raster chart

is a direct copy or scan of an existing paper charts. 

all informations contained with in the chart is directly printed on it

when zooming in and out of a raster chart everything on the chart grows larger or smaller

Vector chart

is a series of points and lines that make up the feauture on a chart 

vector charts are computer generated 

details on the chart can be turned on or off

objects on the chart can be clicked on to learn more details 

ENC layers 

    1. base display 

    2. standard display

    3. full display

    4. custom display

minimum interface requirement of ECDIS

    1. position sensor

    2. heading sensor

    3. speed sensor

ECDIS compliance means

approved ECDIS with approved backup

type approved hardware

type approved software

approved installation

official chart service

training of officers

IHO Standards

1) S-57  ( compilation standard )

     is the data format used for the transfer of digital hydrographic data between national hydrographic           offices and for its distribution to manufactures, mariners and other data users.

2) S-58 

    sets out the validation checks that must be performed on ENCs by hydrographic offices before they          are released to the mariner at sea .

3) S-63 (protection standard)

    piracy protection - IHO data protection scheme for ENC against unauthorized use

    selective access

    authentication - to provide assurance that the ENC data has come from approved source 

4) S-52 ( Display standards)

    determine how ENC data is displayed on an ECDIS screen through symbols ,line styles ,colours etc.

    presentation library is an important part of this standard.

5) S-61 

    RNC product specification

Radar Integrator Board (RIB)

installed in a standard PC

interfaced with any existing radar

converts the Radar video signal to digital

allowing for overlaying a radar picture on the electronic chart

extracts and tracks up to 500 targets 

Difference between raster and vector charts

raster chart                                                         vector chart

                                                          

cheaper and faster                                          costly and time consuming

cannot be changed                                         can be changed                                         

large usage of memory                                  less memory is used                                

can only be added                                          can be added and removed

same as paper chart                                       digital database

other chart will be on different scale             all charts will be on same scale

Mariners Information objects (MIO)

these are digital layers provided for use by the mariners for the purpose of adding additional informations or remarks during passage planning 

information stored in this layer can be recalled and displayed as superimposed information 

ex . T and P notices , navigation warnings 

Safety depth and Safety contour

safety depth is a value entered by the ECDIS operator based on the requirements throughout the passage plan and any further requirements of master

setting the safety contour defines which depths are a danger to navigation

safety contour is a boundary between safe and unsafe waters and generates alarms and warnings against the planned and monitored route . safety contour is highlighted on the chart in bold line 

depth equal to are less than safety depth is high lightened on the chart in bold type when the display of spot sounding is turned on 

safety depth is a visual indication of the limit of navigable waters 

Safety depth    =  ships draft + squat + UKC + CATZOC

Safety contour = ships draft + squat +  UKC + CATZOC

Shallow and Deep contour 

shallow and deep contour do not alarm and are for information purpose only

shallow contour shades the area from the shallow contour to safety depth

Shallow contour  =  ships draft + squat 

Deep contour       = 2 * ships deepest draft

CATZOC  - Category Zone of Confidence

are the values that used to highlight the accuracy of data presented on charts

before ECDIS, mariners access paper chart accuracy via source diagram

ECDIS displays the CATZOC values in ENCs using a triangular shaped symbol pattern . no of stars contained with these symbols denotes the CATZOC value . 

    ex. 6 stars = highest level of data quality

          2 stars = given to the lowest

          1 stars = is not used to avoid confusion with a rock symbol

          U        =  indicates areas not been assessed 

UKC policy 

ocean passage /  deep sea                               = 50%  of deepest static draft

shallow /coastal /SBM /CBM / canal straits = 10% of deepest static draft or 1m whichever is greater

port limits                                                      = 1.5% of ships beam

SCAMIN  =  Scale Minimum

ENC scale used can vary from the best possible to a very small scaled . when using small scale mariner may not wish to display all the object data available for an ENC . under S-57 we can filter the amount of object available through SCAMIN ( except Coastline and display base).

ECDIS chart number

ENC data is complied for a variety of navigational purposes

following codes are used ( usage bands ) / ( navigational purpose )

     1. overview

     2. general

     3. coastal

     4. approach

     5. harbor

     6. berthing 

for vector charts =  GB 6 XXXX . XXX

                               GB         - Great Britain ( Country code )

                                 6           - navigational purpose 

                               XXXX   - individual code

                               XXX      - update no

for raster charts =   CC P XXXXX . EEE

                               CC              - producer code 

                               P                 -  navigational purpose

                               XXXXX     - individual code

                               EEE            -  update no

Guys do you got any doubt , comment below

follow for regular updates

Good luck