NAV 6 Prelim Flashcards
– stands for Electronic Chart Display and Information System
– a computer-based navigation system that displays electronic nautical charts and provides
essential navigational information
– essentially a digital navigation tool used on ships to replace traditional paper charts
ECDIS
Advantages of ECDIS over Paper Charts
● Accuracy
● Efficiency
● Additional Information
● Safety
Electronic charts are updated more frequently and are generally more accurate than paper charts
Accuracy
Route planning navigation are faster and easier with ECDIS
Efficiency
ECDIS can display information from various sources, such as weather data, tidal information, and AIS (Automatic Identification System) data
Additional Information
ECDIS offers enhanced safety features like collision avoidance and grounding alarms
Safety
– digital representations of nautical charts, standardized in content, structure, and format
– also known as vector charts
– datasets to support all types of nautical navigation
– large commercial vessels originally adopted them for the sake of SOLAS compliance, efficiency, and safety benefits
Electronic Navigational Charts (ENCs)
describe the characteristics of an object
Attributes
define how objects are connected
Relationships
Key Data Layers
● Bathymetry Layer
● Topography Layer
● Navigation Aids Layer
● Hydrography Layer
● Obstacles Layer
● Other Layers
– depicts underwater depths, contours, and seabed topography
– includes sounding data, depth curves, and seabed features like canyons and ridges
Bathymetry Layer
represents land features, including coastlines, islands, elevations, and terrain characteristics
Topography Layer
displays aids to navigation such as buoys, lighthouses, beacons, and radio navigation systems
Navigation Aids Layer
provides information about water-related features like currents, tides, and water
depths near the coast
Hydrography Layer
indicates hazards to navigation, including wrecks, obstructions, and underwater
dangers
Obstacles Layer
additional layers may include maritime boundaries, port facilities, and environmental information
Other Layers
Sources of Data Inaccuracy
● Survey Methods
● Generalization
● Data Age
● Human Error
Variations in survey techniques and equipment can affect data precision
Survey Methods
Simplifying complex features for chart representation can introduce errors
Generalization
Changes in seabed topography, coastline, and navigation aids over time can render data outdated
Data Age
Mistakes in data collection, processing, or encoding can lead to inaccuracies
Human Error
Mitigating Data Risks
● ENC Quality Control
● User Verification
● Safety Margin
● Regular Updates
Hydrographic offices implement rigorous quality control measures to ensure data accuracy
ENC Quality Control
Mariners should always cross-reference ENC data with other available information (radar, visual observations, nautical publications)
User Verification
Maintain a safe distance from charted dangers and exercise caution in areas with uncertain data
Safety Margin
Stay informed about ENC updates and corrections to minimize data discrepancies
Regular Updates
– the algorithms that determine which chart information is displayed at specific scales
– essential for preventing chart clutter and ensuring optimal readability
– based on the S-57 ENC standard and IHO Presentation Library
Presentation Rules
Types of Presentation Rules
● Scale-Dependent Rules
● User-Defined Rules
● Priority-Based Rules
automatically adjust chart display based on the current scale
Scale-Dependent Rules
allow mariners to customize chart display based on their preferences and operational requirements
User-Defined Rules
assign priorities to different chart objects, ensuring critical information is always
displayed
Priority-Based Rules
Display Options & Other Data Chart Formats
● Overlay Function
● Split Screen Mode
● Zoom Function
● Rotation Function
● User-Defined Views
combine multiple data layers for comprehensive situational awareness
Overlay Function
view different chart areas or data types simultaneously
Split Screen Mode
adjust chart scale to focus on specific areas of interest
Zoom Function
align the chart with the vessel’s heading for enhanced orientation
Rotation Function
create custom display layouts for specific tasks or preferences
User-Defined Views
create custom display layouts for specific tasks or preferences
User-Defined Views
– simply an electronic image of a paper chart
– digitized by scanning the paper chart and converting each line to a raster picture element or “pixel”
– beyond geo-referencing (positioning the scanned chart so that it appears in the right location with correct x and y coordinates), there is no intelligence or extra data in the image
Raster Charts
“smart charts”, which means the user can click on different features, such as a light or buoy, to retrieve additional information not available in paper or raster charts
Vector Charts
– a directive adopted by the Maritime Safety Committee (MSC) of the IMO, outlining the performance standards for ECDIS
– these standards ensure that all ECDIS equipment meets specific requirements for functionality, accuracy, and reliability, providing a consistent framework for maritime navigation systems worldwide
Resolution MSC.530(106)
ECDIS must be capable of displaying Electronic Navigational Charts (ENCs) and, where necessary, Raster Navigational Charts (RNCs). The system should present chart data clearly and accurately, facilitating effective route planning and monitoring.
Chart Display Requirements
To ensure navigational safety, ECDIS must support the automatic updating of chart
data. This includes integrating updates from authorized hydrographic offices, ensuring that navigators have the most current information at their fingertips.
Automatic Updating
ECDIS must provide robust tools for route planning and monitoring. This includes
functionalities for setting and modifying routes, detecting and alerting to potential hazards, and continuously monitoring the vessel’s position relative to the planned route.
Route Planning & Monitoring
The system should offer an intuitive user interface, making it easy for navigators to access and interpret information. Additionally, ECDIS must have a comprehensive alert system to warn of navigational dangers, system malfunctions, or deviations from planned routes.
User Interface Alerts
To enhance reliability, ECDIS must be supported by adequate backup arrangements.
This ensures that, in the event of a system failure, navigators can continue to access essential chart information and maintain situational awareness.
Backup Arrangements
ECDIS should have capabilities for recording and storing navigational data, which can be vital for post-voyage analysis and in the event of an incident investigation.
Data Recording
Benefits of Complying with RESOLUTION MSC.530(106)
● Enhanced Safety
● Regulatory Compliance
● Operational Efficiency
● Competitive Advantage
Complying with MSC.530(106) ensures that ships are equipped with the most advanced navigational technology, significantly enhancing maritime safety
Enhanced Safety
Meeting the IMO’s performance standards is mandatory for SOLAS (Safety of Life at
Sea) vessels
Regulatory Compliance
Advanced ECDIS systems facilitate efficient route planning and navigation, leading to optimized fuel consumption and reduced operational costs. The ability to update charts automatically and access real-time navigational data further streamlines operations.
Operational Efficiency
Vessels equipped with ECDIS that meet the latest standards are more attractive to
charterers and clients. Demonstrating a commitment to safety and compliance can provide a competitive edge in the maritime industry.
Competitive Advantage
Dangers of Over-Reliance on an ECDIS to the Safety of Navigation
● Loss of Situational Awareness
● System Failures
● Data Inaccuracies
● Human Error
Focusing solely on the screen can hinder visual lookout
Loss of Situational Awareness
Equipment malfunctions can lead to critical information loss
System Failures
Outdated or incorrect chart data can result in misjudgment
Data Inaccuracies
Misinterpretation of ECDIS information can lead to mistakes
Human Error
Main Formats in ECDIS
● Vector Charts
● Raster Charts
Display Modes in ECDIS
Base Display
Standard Display
All Other Display
permanently retained on the ECDIS display
Base Display
Base Display consists of
○ Coastline (high water)
○ Own ship’s safety contour, to be selected by the mariner
○ Indication of isolated underwater dangers at depths of less than the safety contour which lie within the safe waters defined by the safety contour
○ Indication of isolated dangers which lie within the safe waters defined by the safety contour such as : bridges, overhead wires, etc., including buoys and beacons, whether these are being used as aids to navigation
○ Traffic routeing systems
○ Scale, range, orientation and display mode
○ Units of depth and height
to be displayed when the chart is first displayed by ECDIS
Standard Display
Standard Display consists of
○ Display Base
○ Drying line
○ Indication of fixed and floating aids to navigation
○ Boundaries of fairways, channels, etc.
○ Visual and radar conspicuous feature
○ Prohibited and restricted areas
○ Chart scale boundaries
○ Indication of cautionary notes
all other information, displayed individually on demand
All Other Display
Elements in Route Planning & Monitoring
○ planned route lines
○ waypoints
○ cross-track error limits
○ and safety corridors
Elements in Weather & Environmental Data
○ wind direction & speed
○ wave height
○ currents
○ other meteorological & oceanographic data
Elements in User Charts & Annotations
○ user-defined symbols
○ text annotations
○ custom areas or lines
Elements in Overlays
○ radar images
○ AIS targets
○ safety zones
○ other data overlays
Chart Orientations
● North Up
● Course Up
● Head Up
– chart is oriented with true north at the top of the display
– the traditional orientation used on paper charts
– often preferred for general navigation and planning
North Up
– chart is oriented with the ship’s intended course at the top of the display
– useful when following a planned route, as it aligns the chart with the course line, helping mariners to stay on track
Course Up
– chart is oriented with the ship’s current heading at the top of the display
– often used in close quarters, like in harbors or when maneuvering in confined waters, where the mariner needs to quickly interpret what lies ahead of the vessel
Head Up
– the scale according to which the chart information meets the IHO requirements for chart accuracy
– established by the producing Hydrographic Office and encoded in the ENC
– in ECDIS, this scale is critical because it defines the accuracy and detail of the chart data
– the scale at which the chart data was originally created or digitized
Compilation Scale
refers to the categorization of electronic navigational charts (ENCs) based on their scale and intended use
Navigational Purpose/Band in ECDIS
Basic Steps of Route Planning (accd. to ppt)
- Preparation
- Planning the Route
- Optimization
- Safety Check
- Finalizing the Route
- Review & Update
- Documentation
Basic Steps of Route Planning (accd. to sir)
- Appraisal
- Planning
- Execution
- Monitoring
Common Alarms in ECDIS
● Cross Track Error (XTE) Alarm
● Proximity to Hazards Alarm
● Anchor Drag Alarm
● Safety Contour Alarm
● AIS Target Closest Point of Approach (CPA) Alarm
alerts the crew when the vessel deviates beyond a set distance from the planned track
Cross Track Error (XTE) Alarm
ensures the vessel remains within a safe corridor, minimizing the risk of encountering hazards
Cross Track Error (XTE) Alarm
triggers when the vessel is getting too close to identified hazards such as shallow waters, rocks, or wrecks
Proximity to Hazards Alarm
provides early warning to avoid groundings or collisions with underwater obstacles
Proximity to Hazards Alarm
activates if the vessel moves outside a predefined radius while at anchor
Anchor Drag Alarm
helps prevent unintended drifting which could lead to collisions or groundings
Anchor Drag Alarm
warns when the vessel is crossing a safety contour that indicates a change in depth
Safety Contour Alarm
prevents the vessel from entering areas that are too shallow, reducing the risk of grounding
Safety Contour Alarm
triggers when another vessel is predicted to come within a certain distance
AIS Target Closest Point of Approach (CPA) Alarm
provides time to take evasive action to prevent collisions
AIS Target Closest Point of Approach (CPA) Alarm
the most important parameter of all the safety settings for the display of unsafe water areas, detecting isolated dangers and triggering anti-grounding alarms
Safety Contour
an outline which marks the division between safe and unsafe waters
Safety Contour
its sole purpose is to portray spot soundings either in gray for deeper depths or black for shallower depths compared to the safety depth value entered by the navigating officer thereby highlighting the potentially safe and unsafe areas
Safety Depth
What is the default safety contour on ECDIS as per IMO Resolution MSC.530(106) Performance Standards?
30 m
