General bits

Question 1

What is ALRS Volume 1?

Answer 1

• NP 281
• Maritime Radio Stations
• Has information on maritime radio stations worldwide, including frequencies, call signs, MMSI, services offered (safety, distress, weather, medical, etc.).

Question 2

What does ALRS Volume 2 cover?

Answer 2

• NP 282
• Radio Aids to Navigation, Satellite Navigation Systems, Legal Time, Radio Time Signals & Electronic Position Fixing
• Details on navigational warnings, GNSS (GPS, GLONASS, Galileo), time signals, and position fixing systems.

Question 3

What does ALRS Volume 3 cover?

Answer 3

• NP 283
• Maritime Safety Information Services
• Information on NAVAREA warnings, SafetyNET, NAVTEX services, and the Worldwide Navigational Warning Service (WWNWS).

Question 4

What does ALRS Volume 4 cover?

Answer 4

• NP 284
• Meteorological Observation Stations
• Lists meteorological stations, weather broadcasts, and services worldwide, including schedules and transmission details.

Question 5

What does ALRS Volume 6 cover?

Answer 5

• NP 286
• Pilot Services, Vessel Traffic Services, Port Operations and Reporting Systems
• Information on pilotage, port operations, reporting requirements, and Vessel Traffic Services (VTS) worldwide.

Question 6

What is ZOC U?

Answer 6

Unassessed.
No quality information available
Unknown reliability.

Question 7

What does ALRS Volume 5 cover?

Answer 7

• NP 285
• Global Maritime Distress and Safety System (GMDSS)
• Full details of the GMDSS system, including Rescue Co-ordination Centres (MRCCs), SAR facilities, COSPAS-SARSAT, INMARSAT, and distress alerting procedures.

Question 8

What is ZOC B?

Answer 8

Medium confidence.
Position accuracy: ±50m
Depth accuracy: 1m + 2% of depth
Not fully seafloor searched.

Question 9

What is ZOC A2?

Answer 9

High confidence.
Position accuracy: ±20m
Depth accuracy: 1m + 2% of depth
Full area search not required (may be gaps).

Question 10

What is ZOC C?

Answer 10

Low confidence.
Position accuracy: ±500m
Depth accuracy: 2m + 5% of depth
Poor quality, incomplete surveys.

Question 11

What is ZOC D?

Answer 11

Lowest confidence.
Worse than ZOC C
Large positional and depth uncertainties
Data unreliable for navigation.

Question 12

How do you check CATZOC on ECDIS?

Answer 12

Use the pick report / cursor inquiry function — it will display the zone of confidence for that charted area.

Question 13

What does NP 5011 show?

Answer 13

Symbology and Abbreviations used on Paper Charts

Question 14

What doe NP 5012 show?

Answer 14

Admiralty Guide to ENC symbols used in ECDIS

Question 15

What document number is Ocean Passages of the World?

Answer 15

NP 136

Question 16

What is Admiralty Distance Tables?

Answer 16

• NP 350
• Shows shortest distance between ports

Question 17

How often is ALRS updated?

Answer 17

Weekly through Admiralty Notices to Mariners (NMs) and periodically with new editions.

Question 18

What does CATZOC stand for in ECDIS?

Answer 18

Category Zone of Confidence — an ENC quality indicator showing the reliability and accuracy of hydrographic survey data.

Question 19

What is ZOC A1?

Answer 19

Highest confidence.
Position accuracy: ±5m
Depth accuracy: 1m + 2% of depth
Full seafloor coverage (multi-beam/sonar)