The two basic types of electronic chart systems?
Electronic Chart Systems (ECS):
- Generic term for all other types of electronic chart systems.
- If carried on board, up-to-date paper charts must still be used:bFor safe navigation & To fulfil carriage requirements.
Electronic Chart Display and Information System (ECDIS):
- Complies with IMO requirements for SOLAS-class vessels.
- Complex, safety-relevant, software-based system with multiple display and integration options.
- Accepted as a Navigational Chart.
Navigators are expected to:
- Use ECDIS alongside paper charts, or Rely on ECDIS alone (when permitted).
ECDIS – GUIDANCE FOR GOOD PRACTICE MSC.1/CIRC.1503/REV.1
According to SOLAS Chapter V Regulation 19.2.10 what vessle are required to carry ECDIS
Ships engaged on international voyages shall be fitted with an (ECDIS) as follows:
- Passenger ships of 500 gross tonnage and upwards.
- Cargo ships of 3,000 gross tonnage and upwards.
It had a phased-in process, but since 1st July 2018, all vessels now require having it as above.
When will the Sunsetting of Paper charts start happening
UK Hydrographic Office (UKHO) decision:
Will stop producing paper charts by 2026.
Charts affected:
ADMIRALTY Standard Nautical Charts (SNCs)
Thematic Charts
Reason for withdrawal:
Growing preference for digital navigation among marine, naval, and leisure
How do you know your ECDIS is approved?
- Copy of type approval certificate and performance standards applied;
- Connection to emergency source of electrical power, gyro compass, speed log and GPS receiver;
- Back-up arrangement complied with the requirement;
- Be maintained so as to be compatible with the latest applicable InternationalHydrographic Organization (IHO) standards
- When navigation charts are supplied as a backup, the charts should be updated
Hydrographic Organization (IHO) standards
ECDIS Chart 1 and IHO Presentation Library edition 4.0
what is the IHO recommended method for checking that the ECDIS system can display the new symbols
correctly.
To see the new symbols in ECDIS Chart 1, “Information about Chart Display (A, B),” you must have the IHO Presentation Library Edition 4.0 installed. The beacon and buoy features at approximately 15°07.0’N 005°06.5’W will show the magenta ‘d’ symbol only if the ECDIS date range is set between April 1, 2014, and August 27, 2014. If your ECDIS software is not updated to S-52 Presentation Library Edition 4.0, you will not see the new symbols. The IHO does not plan to provide a check data set for this edition
What is ENC & RNC
Electronic Navigational Charts (ENCs)
A database of digitized chart data, displayed seamlessly.
Provide different detail levels for:
Coastal navigation
Harbor approaches
Berthing
Automatically reduce detail when zoomed out to avoid clutter.
User functions:
Select specific data (e.g., lights, navigation marks).
Layer/deselect unnecessary information.
Choose depth contours to enable safety alerts in shallow waters.
Caution: Deselecting information may remove vital data needed for safe navigation.
Offer greater functionality than paper charts.
Raster Navigational Charts (RNCs)
Exact replicas of official paper charts.
Used in the Raster Chart Display System (RCDS).
Limitations:
Lack the advanced features of ECDIS.
Do not allow layering, filtering, or alerts like ENCs.
Use case:
ENCs should be used first choice.
RNCs may be used in RCDS mode if ENC data is unavailable.
DIFFERENCES BETWEEN RASTER CHART DISPLAY SYSTEM (RCDS) AND
ECDIS
Unlike ENCs, RNCs (based on paper charts) show chart boundaries.
*No automatic alarms
RNCs do not trigger alarms (e.g., anti-grounding).
Mariners must manually add features during passage planning:
Clearing lines
Ship safety contours
Isolated danger markers
Danger areas
*Datum and projection differences
*Horizontal datums/projections may differ between RNCs.
*Can cause position shifts, especially near grid intersections.
*Mariners must check how the chart datum relates to the vessel’s position fixing system.
*Not always WGS-84 / PE 90
*Some RNCs cannot be referenced to these datums.
*ECDIS should provide a continuous indication in such cases.
*No simplification of features
RNC features cannot be removed or filtered for task-specific use.
May affect radar/ARPA overlays.
*Limited look-ahead
Without switching scales, look-ahead may be restricted.
Can make it harder to determine range, bearing, or distant object identity.
Orientation issues
Display orientation other than chart-up (e.g., course-up, route-up) may reduce readability of text and symbols.
*No feature interrogation
RNC objects cannot be clicked for additional info.
Mariners should use other publications (sailing directions, etc.).
No automatic safety contour/depth
Safety contours and depths must be manually entered during route planning.
*Color variations
Colors may differ by chart source.
Day/night colors may also vary.
*Scale limitations
RNCs must be used at the paper chart’s scale.
Excessive zooming degrades image quality.
If displayed at a larger scale than the original paper chart, ECDIS provides a warning indication.
*Quality of data
ENCs show data quality directly in ECDIS.
For RNCs, mariners must consult:
Source diagram
Zone of confidence diagram (if available).
Where would I get charts from? Paper and digital
ADMIRALTY Vector Chart Service (AVCS)
- Standards
Produced and distributed according to well-defined international standards.
- Licensing
ENCs are provided under a licence agreement.
Licence allows use for defined periods of time.
- Flexibility
AVCS Folios and ENC Units can be added to a licence at any time.
Licence durations available: 3, 6, 9, or 12 months (subject to data supply agreements).
Provides maximum choice and flexibility to match chart holdings with operational patterns.
SENC Services
System ENC (SENC) and AVCS
Conversion to SENC
When loaded into an ECDIS, ENCs are converted to the system’s proprietary format called System ENC (SENC).
Shore-based conversion
To improve loading efficiency, some service providers convert AVCS ENCs to SENC ashore.
These converted files are then sent to the vessel, usually via download.
Assurance
AVCS SENC services carry full ADMIRALTY assurance and accreditation.
Pay as you Sail (PAYS)
PAYS (Pay As You Sail) Subscriptions – AVCS
Coverage & Permits
Provides vessels with permits for the majority of the AVCS portfolio.
ENCs are available for voyage planning.
Avoids purchasing ENCs individually (if Producer allows ENC inclusion in PAYS).
Charges apply only when vessel sails across the ENC coverage area.
Loading ENC Data
ENC data must still be loaded to ECDIS (manually or automatically).
New ENC Permits supplied by ADMIRALTY Chart Agent whenever ENCs are added or removed from the licence.
Permits must be installed on ECDIS before loading new AVCS discs.
Updates
Weekly AVCS update data provided by ADMIRALTY Chart Agent.
Updates may also be requested/downloaded via ECDIS or other software.
New AVCS DVDs issued weekly – data is cumulative.
To update ECDIS:
Load ENCs from the latest AVCS discs, OR
Receive only the updated data for ENCs you already hold.
What are the significances of the Readme file
**AVCS README.TXT File
Content
Each AVCS disc and downloaded exchange set includes a README.TXT file.
Contains important safety information.
Usage
Mariners should read the file before using the service.
Must be checked weekly for updates.
ENC data on disc
AVCS DVD Service
Content & Distribution
Contains all base and update data.
Distributed on two discs every week.
Simplifies ECDIS processing when reading data.
Organisation
ENCs arranged into nine folders (Volumes) on each disc.
DVDs are named “M01X01”.
Updates
If multiple update discs are received, use only the most recent disc.
Reason: Discs are cumulative (latest contains all previous updates).
What are the SOLAS-Approved Back-Up Options for ECDIS
Option 1: Second ECDIS
Must be fully compliant and independent of the main ECDIS.
Connected to:
- Main and emergency power supply (SOLAS Chapter II-1).
- Continuous position fixing system.
- Gyro compass.
- Speed and distance measuring devices.
Back-up ECDIS must have:
- Chart database loaded.
- Voyage plan loaded before starting the voyage.
Option 2: Paper Charts
- A folio of paper charts meeting SOLAS carriage requirements.
- Must be kept up to date with the latest Notices to Mariners.
- Must cover the intended voyage and show the passage plan
What are the SOLAS-Approved Back-Up Options for ECDIS Specifically for Yachts under 3000gt
Accepted carriage combinations
1 × Paper chart folio.
1 × ECDIS unit + 1 × Paper chart folio.
2 × ECDIS units, both working independently:
Second ECDIS must be connected to:
Independent power supply.
Separate GNSS position input.
Use of RCDS mode (Raster Chart Display System)
Applied when ENC coverage is lacking.
**Requirement: **
Maintain an appropriate folio of up-to-date paper charts for areas with only raster coverage.
MCA Marine Guidance Notice (MGN 285 M+F)
Before MCA approval of ECDIS in RCDS mode as a primary means of navigation:
A risk assessment must be undertaken.
Masters and navigation officers preparing passage plans must:
Conduct risk assessment of trading areas.
Determine if there is suitable ENC coverage.
Decide whether an Appropriate Paper Chart (APC) folio is required.
Important notes
Not all sea areas have ENC chart coverage.
RCDS mode may be used for primary navigation only where no ENCs exist, subject to MGN 285 risk assessment.
Chart Symbols
Isolated Danger Symbol (ENC / ECDIS)
Purpose
Identifies underwater features that pose a danger to navigation.
Examples: wrecks, rocks, wellheads, fish havens, diffusers.
Standard (S-52)
Defines symbols for such features (similar to paper chart symbols).
ECDIS uses the safety contour value to decide how features are displayed.
Display of symbol
Shown when a feature has a depth ≤ safety contour entered by the user.
Appears in deeper water areas beyond the safety contour (hazard in otherwise “safe waters”).
Notes / Restrictions
Applied only to wrecks, rocks, and submerged obstructions.
Not applied to soundings.
Usually represents a point feature.
For area features (e.g., foul area), symbol appears at the centre
how to spot unrelible depth
CATZOG name and discrible the levels
Unknown Object Vector Format Symbol
Question Mark Symbol in ECDIS
When it appears
Displayed when ECDIS encounters a feature in ENC data it cannot display properly.
May appear alongside or in place of the intended symbol.
Main exam reason
ECDIS does not have the latest S-52 Presentation Library installed.
Without it, the system lacks instructions to draw new feature types from ENC data.
How it is shown
A large question mark appears in the position of the feature.
The feature can be interrogated using the ECDIS pick report function.
What are Limitations of the ECDIS?
Do not over-rely on ECDIS.
Always cross-check with:
Other navigation sources.
Visual lookout (most important).
ECDIS benefits:
Improves situational awareness.
Gives officers more time to maintain lookout.
ECDIS dangers if misused:
Can cause accidents instead of preventing them.
Common mistakes (ECDIS-assisted groundings):
Passage plan not hazard-checked with check-route function.
Plan not verified by Master.
Wrong depth settings.
Wrong cross-track error (XTE) settings.
Incorrect ENC scale used
ECDIS – Alarm Management & Limitations
Alarms → Vary by maker, control levels differ, some allow disabling/scale choice, sometimes inoperative & unreported.
Display location → Poor placement reduces monitoring; forward console best.
Training → Masters/officers often under-trained.
Anomalies → Hardware + software + data mix → bugs possible.
Screen clutter → Small-scale ENCs + zoom out = clutter.
Data quality → No source diagrams; use CATZOC for reliability checks.
Updates → Must update to latest S-52 library or features may not display.
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IRPCS42
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Buoyage61
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Flags10
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Checklist19
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Publications82
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Lights, Shapes & Sounds128
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Role of the OOW79
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Passage planning56
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Pilots16
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L.S.A179
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Compass137
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COSWP121
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Radar62
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AIS. LRIT & BNWAS39
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ECDIS61
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COLREGS143
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Chart Work46
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Position Fixes39
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Sextant34
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Fire25
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MOB30
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What is so what32
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Nav Equipment63
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Steering Systems72
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STCW51
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Radar Plotting & Arpa30
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Salvage31
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ISPS30
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LYC38
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MLC29
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MET37
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Stability61
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GMDSS31
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Medical & Rope35
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Marpol30
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ISM30
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Drive a Boat30
