ECDIS Flashcards
Purpose / advantages of ECDIS
Reduced workload for OOW
Improved SA
Admirality Information Overlay
Information Layering
Safety Alarming
Real time position information
Automatic log book recording
Quick and easy corrections (done by professionals)
Disadvantages of ECDIS
Over reliance
Relies on integrity of feed inputs
Information overload
Underscaling/overscaling
Requires specialty training
Alarm apathy
RASTAR charts can still be displayed
Potential ‘old’ survey information
High potential for user error
What makes an ENC
It meets the IMO performance standards under MSC 232 and therefore meets the carriage requirements of SOLAS
What Inputs must an ECDIS have?
GPS x 2
Speed (water log)
Gyro
UPS
Additional:
AIS/RADAR overlay
Disadvantages of ECDIS
Over-reliance by OOW
Requires UPS
Specific training required
Alarm apathy
Clutter by info overload
Over/Underscaling
MSC 232 (updated to MSC 530)
Performance standards for ECDIS
Order of importance in Governance
IMO (SOLAS CH 5, Performance standards)
IHO (software standards)
IEC (international Electrotechnical Commission) produced the IEC 61174-15
(hardware standards)
S52
Specifications for chart content and Display aspects of ECDIS
Current Version is S52 4.0
S57
Transfer standards for Digital Hydrographic Data
S58
ENC validation Checks
S61
Product specification for Rastar Navigational Charts
S63
Digital Data Incription
S100
New standards for Bathymetrey and geographical Data
When can we run in RCDS
Rastar Chart Display System
No ENC available
Risk assessment has been carried out on the use of RCDS
An appropriate back up portfolio of Paper Charts is present
SENC
System Electronic Navigational Chart
A ENC is considered a SENC, when it is APPROVED, and has undergone lossless transformation of the database
Only an SENC is allowed for a paperless Bridge
WEND
World wide Electronic Chart Database
Ensures globally consistent high level of quality
RENCs
Regional Electronic Navigational Chart Co-ordination Centres
Distribution of charts
Two Particular RENCs
IC-ENC, international centre, hosted by the UKHO
Primar, Hosted by Norway
Shallow Contour
User chosen contour depth depicting unsafe waters beyond. Usually set to the Ships Draft
Colour behind will be Dark Blue
Safety Contour
User set contour line depicting possible unsafe water on the other side. The system will highlight in bold the next deep contour line from the users chosen depth.
ESSENTIAL for safe navigation and monitoring
Safety Contour calculating
Draught + UKC allowance , swell, list etc + allowance for squat + Potentially HOT as well.
Colour between Safety and Shallow contour will be light blue
If it doesn’t match the set depth, it will automatically choose the next available depth contour
I.e. safety contour set to 7m. the ECDIS will choose a 10m contour
Safety Depth
User Chosen depth, beneath which isolated sountings will be in bold. Usually set to match the safety contour
ESSENTIAL for safety of navigation and monitoring
Deep contour
User chosen contour line before which is safe navigable water.
Colour between deep and safety contour will be grey
Colour before deep contour will be white
Safety frame
‘Guard zone’ similar to on a radar.
User set, commonly set to 1 NM either side in normal navigation, and 15 minutes ‘look ahead’ time
Calculation (Speed x Look ahead distance) / 60 = NM looking ahead distance
Route check in which compilation
1:1
Maximum number of satellites at one time for GPS
24
Space segment
satellites themselves
User segment
Ships, gps systems etc
Control segment
Control stations ashore
What does the control station do?
monitors satellites and positions and reports data to the master station through GBAS
6 sources of errors for GPS
Satellite clock
Position of satellite
Ionospheric delay caused by ionosphere
Tropospheric delay caused by Troposphere
Multi path error, indirect path to vessel (bouncing off another vessel etc)
Receiver noise error
Receiver clock error
Dilution of Precision
When satellites are too close together and have a poor angle of cut
What DOP are navigators concerned with?
Horizontal (HDOP)
Ground based augmentation system
Provides differential corrections and integrity monitoring of Global Navigation Satellite Systems
Space based augmentation system
Provides differential corrections and integrity monitoring ( by the satellites ) of Global Navigation Satellite Systems
DGPS
GPS system set up to receive differential corrections from GBAS/SBAS
When an ECDIS is being used to satisfy the carriage requirements of SOLAS, what must be present?
Copy of type approval certificate, and standards applied
Connection to emergency source of electrical power, gyro compass, speed log and GPS receiver
Be maintained and up to date with the latest IHO standards (International Hydrographic Organisation)
A back up arrangement
When paper charts are the backup, these must also be up to date
Who is ECDIS mandatory for?
Passenger vessels over 500GT
Cargo Ships over 3000GT
Hence it is not mandatory on yachts, though most will carry it
Where do we get digital charts from? in what form
AVCS Admiralty Vector Chart Sevices
Single ENC units or Folios can be licensed for limited periods, 3,6,9,12 months,
Or by PAYS, Pay as you Sail
Where you get full coverage for passage planning, but only pay for the ENCs your vessel crosses
Where can we get more guidance on ECDIS in RCDS mode?
A
MGN 285 - Electronic Charts - Use of risk assessment methodology when operating ECDIS in RCDS Mode
Pros of Rastar Charts
User friendly as they are scans of original paper charts (familair)
Are approved as they are admiralty charts
Cheap to produce
Global coverage
Negatives of Rastar Charts
Large file size
Do not meed IMO carriage requirements for a paperless bridge
Not scalable
Requires a fully up to date chart portfolio
Risk assessment must be made in the use of rastar charts
Not seamless, has boundaries
Not inherently intelligent (no alarms, layers, indications)
Pros of Vector Charts
Can be interrogated
Alarms and Indications
Scalable with no distortion
Admiralty Information over layering
Own ship route monitoring
User set layers
Smaller file data
Apparently seamless joint between charts
Negatives of Vector charts
Same Survey data as paper charts
Not all approved data
Unfamiliar Symbols to new users (specialist training required)
High chance of a false sense of security
Clutter in the wrong compilation scale
Expensive and timely to produce
Items present in standard display
Display base + Minimum required for safe passage planning
Spot soundings
Visual and radar conspicuous objects
Chart scale boundaries
Drying line
Indication of fixed and floating aids to navigation
Boundaries of fairways, channels, etc.
prohibited and restricted areas
indication of cautionary notes
chart scale boundaries
Items present in Display Base
Minimum amount of layered information that will ever be shown on ECDIS
Own ship safety contour
N up arrow
Coastline (high water)
Compilation scale in use
Scale, range
Original compilation scale
Isolated underwater dangers that lie within the safety contour
Hazardous wrecks
Traffic routing systems
ONLY TO BE USED FOR OVERVIEW PLANNING
ECDIS vs ECS
ECDIS in an electronic chart display and information system
Officially approved navigation information system
Rigorous standards in terms of hardware, software, charts and backup arrangements by IMO and IHO
Can be used as a paperless bridge under SOLAS chapter V
An ECS is any electronic chart system that does not meet these requirements, and cannot be used for a paperless bridge
Meeting Paperless bridge standard (approved ECDIS system)
2 fully independent systems
2 Individual UPS
Connected to Emergency power
Display both Rastar and Vector charts
Must have seperate GPS inputs
Heading info (gyro) Speed info feed
Must display AIS, ARPA and Radar information
Must be able to be corrected on a weekly basis, or manually corrected
Must have User overlay information layer capabilities
Hardware must be approved by the IEC
ECDIS must in term display a SENC
Chart coding
1st two letters country code
1st number usage
Next numbers up to decimal is chart number
Numbers after the decimal is the corredtion number
What is a Rastar Chart?
High quality scan of an existing paper chart
What is a Vector Chart?
Multi layered database of information
What is CATZOC
Category Zone of Confidence
Reliability indication of:
Position and depth
Isolated danger symbol ECDIS
Will display isolated dangers less than the user set safety contour with this symbol
List of ECDIS alarms
Crossing safety contour
Deviate from route
Position system failure
Approaching a critical point
Non ENC Area
Different Geodetic Datum
What is an ECDIS alarm?
Audible and visual means of alerting the user to something that requires their immediate attention
What are ECDIS Indications?
Alert a user to something that MAY lead to danger if we do not act
List of ECDIS Indications
Information overscale
Information underscale
Larger ENC available
Route plan over a safety contour
Route plan over a specified area
Position system failure (planning mode)
System test failure
ECDIS role in integrity monitoring
Detecting chart errors
Position accuracy monitoring
Handling sensor failures
Display integrity and reliability
Safety parameter Monitoring
Alarm generation
USER role in ECDIS integrity monitoring
Continuous use of traditional navigational techniques
Monitor feed inputs (gyro, speed, GPS)
Interrogate alarms and monitor route
Visually check route before monitoring in 1:1 scale
Verify the integrity of data being fed into the ECDIS
Overlays (RADAR, ARPA, AIS) verified
Ensuring Charts are up to date on ECDIS
ECDIS should display this data prominently on the screen
Or in the chart properties section, to the right side of the screen
We can also check our chart catalogue, and the charts not up to date will appear in orange
This interrogation of the properties can be type specific
Updating process of ECDIS
Receive the AVCS DVD from the chart service, and insert.
Read the ‘read me’ file, and update with the most recent N/Ms accordingly
These can be received through email nowadays
How do we check our ECDIS itself is updated?
Within the system information menu
