COMPREHENSIVE GUIDE TO GPS,
ECDIS, AIS, AND RADAR IN MARINE
NAVIGATION. EXAM QUESTIONS AND
ANSWERS 100% PASS
GPS (Global Positioning System) - ANS GPS is a satellite-based positioning system.
How GPS works - ANS A GPS receiver measures the travel time of signals from multiple
satellites to compute its position via trilateration (requires signals from at least four satellites).
Common errors in GPS - ANS GPS accuracy can be degraded by satellite clock or orbit errors,
atmospheric delays (ionosphere/troposphere), multipath (signal reflections off structures or
terrain), poor satellite geometry (high dilution-of-precision), antenna placement, or intentional
interference.
Differential GPS (DGPS) - ANS Differential GPS (DGPS) and augmentation systems help
mitigate many errors.
ECDIS (Electronic Chart Display & Information System) - ANS ECDIS is an integrated navigation
and collision-avoidance charting system.
Functionality of ECDIS - ANS It displays digital ENCs (Electronic Navigational Charts) with
topographic and hydrographic data on a latitude-longitude grid so the ship's position, course,
and nearby hazards are shown in real time.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Integration in ECDIS - ANS It integrates sensors (GPS, gyro, log, echo sounder, anemometer,
radar, etc.) to automatically update the vessel's position, course, ETA, and cross-track error.
Route planning in ECDIS - ANS Route planning, monitoring and automatic track-control are
supported (alarms trigger if vessel strays off track or approaches danger).
Benefits of ECDIS - ANS ECDIS bundles chart data and sensor inputs, greatly reducing manual
plotting and workload.
Real-time position in ECDIS - ANS The ship's real-time position is shown automatically (no
need for manual fixes), so the officer always knows where the vessel is.
Display features of ECDIS - ANS Displays are vector-based and selectable (data can be filtered
or shown in layers), and the screen is dimmable for night operations.
Radar overlay in ECDIS - ANS ECDIS supports radar overlay and up-to-date charts (paperless
compliance), automatic route monitoring (e.g. minimum depth checks, XTE alarms), and helps
in special maneuvers (e.g. man-overboard).
Risks of ECDIS - ANS ECDIS depends on accurate data and proper settings.
Over-reliance on ECDIS - ANS Over-reliance can give a false sense of security; the operator
must still maintain lookout and verify system performance.
Specific risks in ECDIS - ANS Specific risks include incorrect position determination (e.g. GPS
errors), inaccurate or outdated chart data, and setting inappropriate safety parameters (depth
contours, alarms).
System failures in ECDIS - ANS System failures or software bugs (no GPS input, no update,
hardware faults) may go unnoticed but can disable alarms or mislead operators.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
ECDIS, AIS, AND RADAR IN MARINE
NAVIGATION. EXAM QUESTIONS AND
ANSWERS 100% PASS
GPS (Global Positioning System) - ANS GPS is a satellite-based positioning system.
How GPS works - ANS A GPS receiver measures the travel time of signals from multiple
satellites to compute its position via trilateration (requires signals from at least four satellites).
Common errors in GPS - ANS GPS accuracy can be degraded by satellite clock or orbit errors,
atmospheric delays (ionosphere/troposphere), multipath (signal reflections off structures or
terrain), poor satellite geometry (high dilution-of-precision), antenna placement, or intentional
interference.
Differential GPS (DGPS) - ANS Differential GPS (DGPS) and augmentation systems help
mitigate many errors.
ECDIS (Electronic Chart Display & Information System) - ANS ECDIS is an integrated navigation
and collision-avoidance charting system.
Functionality of ECDIS - ANS It displays digital ENCs (Electronic Navigational Charts) with
topographic and hydrographic data on a latitude-longitude grid so the ship's position, course,
and nearby hazards are shown in real time.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Integration in ECDIS - ANS It integrates sensors (GPS, gyro, log, echo sounder, anemometer,
radar, etc.) to automatically update the vessel's position, course, ETA, and cross-track error.
Route planning in ECDIS - ANS Route planning, monitoring and automatic track-control are
supported (alarms trigger if vessel strays off track or approaches danger).
Benefits of ECDIS - ANS ECDIS bundles chart data and sensor inputs, greatly reducing manual
plotting and workload.
Real-time position in ECDIS - ANS The ship's real-time position is shown automatically (no
need for manual fixes), so the officer always knows where the vessel is.
Display features of ECDIS - ANS Displays are vector-based and selectable (data can be filtered
or shown in layers), and the screen is dimmable for night operations.
Radar overlay in ECDIS - ANS ECDIS supports radar overlay and up-to-date charts (paperless
compliance), automatic route monitoring (e.g. minimum depth checks, XTE alarms), and helps
in special maneuvers (e.g. man-overboard).
Risks of ECDIS - ANS ECDIS depends on accurate data and proper settings.
Over-reliance on ECDIS - ANS Over-reliance can give a false sense of security; the operator
must still maintain lookout and verify system performance.
Specific risks in ECDIS - ANS Specific risks include incorrect position determination (e.g. GPS
errors), inaccurate or outdated chart data, and setting inappropriate safety parameters (depth
contours, alarms).
System failures in ECDIS - ANS System failures or software bugs (no GPS input, no update,
hardware faults) may go unnoticed but can disable alarms or mislead operators.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
