ECDIS-L1.2

ECDIS in navigation and its limitations

ECDIS is powerful but must be used with judgement, and its known limitations have caused accidents. This lesson covers using ECDIS on passage and the traps to avoid.

Plan, monitor, cross-check

  • Plan and check the route with the ECDIS route-check function against the ENCs.
  • Monitor the passage with the cross-track, look-ahead and safety alarms active.
  • Cross-check the position by an independent means — radar and visual — and do not blind-trust GNSS.
  • Keep an approved backup arrangement — a second ECDIS or paper charts — per the ship's approval.

The great danger of ECDIS is over-reliance: the display looks equally confident whether the underlying survey is good or coarse and whether the GNSS position is right or wrong. The source-data quality is shown by the CATZOC rating, and a poorly surveyed area demands extra caution. Generic ECDIS training teaches the concept, but the officer must also complete type-specific familiarisation on the exact equipment fitted, because the menus and functions differ between makes.

WARNING — Over-reliance is the real danger ECDIS shows a confident picture even when the survey is coarse or a sensor is wrong. Keep a visual and radar lookout, check the CATZOC, and never let alarms be silenced into meaninglessness.

NOTE — Type-specific training is still required Generic ECDIS teaches the principles; you must also complete type-specific familiarisation on the exact equipment on your ship, because the operation differs between makes.

Practice questions

5 questions
recallcore

recall · core

A key limitation an ECDIS user must guard against is: (a) Charts being too accurate (b) Over-reliance on GNSS without independent cross-checks (c) Too many alarms by design (d) Having a backup

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recall · core

The CATZOC rating tells the officer about the: (a) Battery level (b) Reliability of the underlying survey data (c) Chart price (d) AIS range

recallcore

recall · core

Generic ECDIS training must be supplemented by: (a) Nothing (b) Type-specific familiarisation on the actual equipment (c) A radio course (d) A stability course

recallcore

recall · core

An approved ECDIS backup is: (a) Not required (b) A second independent ECDIS or an appropriate paper-chart folio (c) A mobile phone (d) A second GPS only

recallcore

recall · core

On passage, ECDIS position should be: (a) Trusted blindly (b) Cross-checked against radar and visual means (c) Ignored (d) Used only in port

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