Monday, June 8, 2020

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 






















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