Which device most directly provides the input to satisfy EPFS on an ECDIS?

• A. Gyrocompass
• B. Echo sounder
• C. GNSS receiver
• D. VHF radio

Answer: (C)

EPFS relies on having a reliable position input to place the vessel correctly on the chart. The GNSS receiver performs this role by calculating your exact geographic coordinates (latitude and longitude) from satellite data and feeding those coordinates to the ECDIS, keeping the vessel’s position updated in real time. The gyrocompass provides heading information, not position; the echo sounder gives depth data; and the VHF radio is for communication. Because precise position is what EPFS needs to display and update the vessel’s location, the GNSS receiver is the direct input.