Navigation & Chart Integration Flashcards

What does ARPA stand for in marine radar systems?

Answer: Automatic Radar Plotting Aid

ARPA stands for Automatic Radar Plotting Aid, a system that automatically tracks radar targets and calculates collision risk data.

What is the primary purpose of radar overlay on an ECDIS display?

Answer: To superimpose live radar returns onto the electronic chart for correlated situational awareness

Radar overlay on ECDIS superimposes live radar returns onto the electronic navigational chart, enabling direct comparison of radar contacts with charted features.

In radar navigation, what does 'true motion' display mode show?

Answer: Own ship and targets moving according to their actual courses and speeds over ground

True motion mode moves own ship across the display according to its actual course and speed, while stationary objects remain fixed and moving targets reflect their real movement.

What is the purpose of a parallel index (PI) line in radar navigation?

Answer: To maintain a safe passing distance from a navigational hazard by tracking a fixed bearing line

A parallel index line is drawn parallel to the intended track at a set distance from a hazard, allowing the navigator to monitor safe clearance continuously.

What is MARPA, as distinguished from full ARPA, in marine radar?

Answer: Mini Automatic Radar Plotting Aid, a simplified target-tracking feature found on smaller vessel radars

MARPA (Mini Automatic Radar Plotting Aid) provides limited automatic target tracking on smaller, less powerful radars compared to full ARPA systems.

Which NMEA sentence is most commonly used to transfer radar target data to an ECDIS or chartplotter?

Answer: NMEA 0183 TTM (Tracked Target Message)

The NMEA 0183 TTM (Tracked Target Message) sentence transmits ARPA/MARPA tracked target data including bearing, range, CPA, and TCPA to connected navigation systems.