Bridge Procedures

Question 1

Discuss the choice of range scales for Plotting when using radar.

Answer 1

Traffic density, speed of own ship and the frequency of observation. It is not advisable to commence plotting on a short range scale. Advance warning of the approach of other vessels, changes in traffic density, or proximity of the coastline, should be obtained by occasional use of longer range scales.

Question 2

Discuss Parallel Indexing techniques.

Answer 2

This enables the watchkeeper to continuously monitor the vessel’s position in relation to a pre-determined passage plan. The principle uses electronic index lines which allows the user to determine where they are in relation to Cross track error of the planned track. MGN 379

Question 3

Precautions when using Parallel indexing.

Answer 3

It does not remove the requirement for position fixing at regular intervals i.e visual bearings. MGN 379

Question 4

What Precautions when using radar for position fixing and monitoring, should the user check:

Answer 4

1) The identity of the fixed object.
2) The radar’s overall performance.
3) The gyro error and accuracy of the heading marker alignment.
4) That parallel index lines are correctly positioned on a suitable display.
5) The accuracy of the variable range marker, bearing cursor, and fixed range rings. MGN 379

Question 5

What check’s should be carried out to the Radar?

Answer 5

Frequent checks of the radar performance must be made to ensure that the quality of the
display has not deteriorated. The performance of the radar should be checked using the Performance Monitor before sailing
and at least every four hours whilst a radar watch is being maintained. MGN 379

Question 6

Radar speed input?

Answer 6

In determining a target’s aspect by radar; the calculation of its true track is dependent on the choice and accuracy of the own ship’s course and speed input. A ground-stabilised target plot may accurately calculate the ground track of the target, but its heading may be significantly different from its track when experiencing set, drift or leeway. Similarly, a
sea stabilised target plot may be inaccurate when own ship and the target, are experiencing
different rates of set, drift or leeway. MGN379

Question 7

Radar Gyro Failure?

Answer 7

Watch-keepers should determine and apply the magnetic compass errors. The true vector function of automatic plotting and tracking equipment should be operated with caution when the heading input is derived from a Transmitting Magnetic Compass (TMC). MGN 379

Question 8

GPS Accuracy and reliability?

Answer 8

GPS provides a global positioning capability giving 95% accuracy in the order of +/- 25 metres.
Differential GPS (DGPS) is also available in many areas of the world including the UK coast. MGN 379

Question 9

Datum and chart accuracy?

Answer 9

GPS positions are referenced to the World Geodetic System 1984 Datum (WGS 84). This may
not be the same as the horizontal datum of the chart in use, meaning that the position when
plotted may be in error. DGPS positions are normally referenced to WGS 84 though
regional datums, corresponding to WGS 84, may be used [e.g. North American Datum 1983
(NAD 83) in the USA] and European Terrestrial Reference System 1989 (ETRS 89).

Question 10

ECDIS alarms and indications?

Answer 10

• Crossing safety contour - Alarm
• Area with special conditions -Alarm or Indication
• Deviation from route - Alarm
• Positioning system failure - Alarm
• Approach to critical point - Alarm
• Different geodetic datum - Alarm
• Malfunction of ECDIS - Alarm
• No ENC available

Question 11

What is MGN 610?

Answer 11

Navigation: SOLAS Chapter V - Guidance on the
Merchant Shipping (Safety of Navigation) Regulations
2020

Question 12

Required Publications?

Answer 12

1. International Code of Signals (IMO)
2. IAMSAR Manual Vol III
3. Mariners’ Handbook (UKHO)
4. Merchant Shipping Notices, Marine Guidance Notes and Marine Information Notes (MCA)
5. Notices to Mariners (UKHO)
6. Notices to Mariners – Annual Summary (UKHO)
7. Lists of Radio Signals (UKHO)
8. Lists of Lights (UKHO)
9. Sailing Directions (UKHO)
10. Nautical Almanac
11. Navigational Tables
12. Tide Tables
13. Tidal Stream Atlases
14. Operating and Maintenance Instructions for Navigational Aids carried by the Ship.

Question 13

CATZOC A1?

Answer 13

Position Accuracy ± 5 m + 5%
Depth Accuracy =0.50 + 1%d
Seafloor Coverage - Full

Question 14

CATZOC A2?

Answer 14

Position Accuracy -± 20 m
Depth Accuracy = 1.00 + 2%d
Seafloor Coverage - Full

Question 15

CATZOC B?

Answer 15

Position Accuracy ± 50 m
Depth Accuracy = 1.00 + 2%d
Seafloor Coverage - Full

Question 16

CATZOC C?

Answer 16

Position Accuracy ± 500 m
Depth Accuracy = 2.00 + 5%d
Seafloor Coverage - Full

Question 17

CATZOC D?

Answer 17

Position Accuracy - Worse than C
Depth Accuracy - Worse than C
Seafloor Coverage - Full search not achieved

Question 18

CATZOC U?

Answer 18

Unassessed - The quality of the bathymetric data has yet to be assessed