Navigation General · ECDIS
An ENC (Electronic Navigational Chart) differs from a raster chart (RNC) in that the ENC is:
- AA simple scanned image of a paper chart
- BA vector database of intelligent, layered objects the ECDIS can query, alarm on, and re-scale cleanly✓ Correct
- CAlways in black and white
- DUpdated only once per decade
Explanation
An ENC is official vector data: each feature is an object with attributes, so ECDIS can detect dangers, generate alarms, and seamlessly re-scale. A raster chart is merely a scanned image with no underlying intelligence, so it cannot trigger anti-grounding alarms.
Authority: IHO S-57/S-101; IMO ECDIS standards
Practice the full Navigation General bank
Free spaced-repetition quizzing across 2190 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Navigation General questions
- ECDIS
On an ECDIS, the 'safety contour' is used to:
- Dead Reckoning
A vessel departs a known position at 0800 on course 090°T at 12 knots. What is the DR position at 1100?
- Time-Speed-Distance
Using the 60 D = S × T formula, how long will it take a vessel traveling at 15 knots to cover 45 nautical miles?
- Time-Speed-Distance
A vessel travels 90 nautical miles in 6 hours. What is the vessel's speed?
- Dead Reckoning
Which of the following is the best definition of a Dead Reckoning (DR) position?
- Set & Drift
A vessel steers 000°T at 10 knots for 2 hours. The observed position shows the vessel is 4 nm east of the DR position. What is the set and drift of the current?