Radar and Bridge Equipment

Question 1

RADAR Essentials

Answer 1

• It is essential for the operator to be aware of the radar’s current performance which is best ascertained by the performance monitor. The echo return from a distant known target should also be checked.
• Be aware of the possibility that small vessels, ice floes or other floating objects such as containers may not be detected
• Echoes may be obscured by sea or rain-clutter. Correct setting of clutter controls will help but may not completey remove this possibility. When plotting larger targets on medium range scale, the display should be periodically switched to a shorter range, and the clutter controls adjusted, to search for less distinct targets.
• The oberserver must be aware of the arcs of blind and shadow sectors on the display caused by masts and other onboard obstructions. These sectors myst be plotted on a diagram and placed near the radar display.
• 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

Question 2

Radar Pre Depature Checks:

Answer 2

1. 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
2. VRM Checked again range rings
3. ERBL cross checked again compass

Good radar practice:

• The quality of the performance of the radar needs to be checked regularly. A performance monitor if fitted should be used for this purpose
• Misalignement of the heading marker, even if only slightly, can lead to dangerously misleading interpretation of potential collision situations.
• Small vessels, Ice, and other floating objects such as containers may not be detected by radar**​
• Video processing techniques should be used with care
• Echoes may be obstructed by sea or rain clutter
• Masts or other structural feartures may cause shadow or blind sectors on the display.

Question 3

How would you setup your X-Band Radar when navigating a coastal passage plan 6NM from Land?

Answer 3

X-Band = 3cm

• Less affected by the target swap, therefore used for Collision Avoidance
• North Up
• Relative Motion
• Relative Vectors
• True Trails
• Sea Stabilised (Collision avoidance) (Input = STW)
• 6nm range scale

A sea stabilised display will indicate all targets motion through the water. A ground stabilised display will indicate all targets motion over the ground

Question 4

How would you setup your S-Band radar when navigating a coastal passage 6NM from land?

Answer 4

S-Band = 10cm

• North Up
• Relative Motion
• Relative Vectors
• True trails (switch between true / relative trails
• Ground Stabilised (for position fixing and long range detection)
• 12nm range scale
• Note: When coming into the Solent and towards Southampton I would put both radars on ground stabilised as the ARPA will not be used for collision avoidance because the CPA only needs to be 0.3nm within performance criteria. Collision avoidance is now done on steady bearings.

Question 5

What must be posted on the bridge with regards to Radar and Navigation?

Answer 5

• Must have a blind sector chart by the radars on display (or programmed)
• Additionally for steering
• Must have a diagram of how to change over from Auto to Manual steering on the helm
• Must have a talk back system in place on the bridge and also down by the steering gear - Possible gyro repeater

Question 6

What 3 different types of information does AIS show?

Answer 6

1. Static
   a. Length
   b. Breadth
   c. Call sign
   d. MMSI
   e. Type of ship
2. Dynamic
   a. Course, speed of vessels and own vessel (GPS fed)
3. Voyage Data
   a. Draught
   b. Number of People
   c. Destination and ETA
   d. Navigational Status

Question 7

NAVTEX - 518 kHz

Answer 7

• Navigational Warning System via text
• 490 kHz for local language
  
  • A= Nav Warnings
  • B = Met Warnings
  • D = Search and Rescue / Piracy
  • L = Additional Nav Warnings

ABDL - Cannot be switched off

Question 8

BNWAS

Answer 8

Bridge Navigational Watch Alarm System

• IMO Performance Standards = ANNEX 11 - Resolution MSC.128(75)
  
  • Automatic function
  • Manual On - Manual Off A
  • Audible Alarm between 3-12 mins
  • Second Alarm to senior officer or master
  • Third Alarm to ships crew (general alarm)

Question 9

What is ARPA

Answer 9

Automatic Radar Plotting Aid -

• Computerised calculation of the course and speed of the other vessel that gives CPA and TCPA
• Also used in trial manoeuvres

Question 10

What are the errors of ARPA?

Answer 10

• Input errors (shit in - shit out) so wrong course or speed the info coming out will be incorrect
• Regardless of wrong input the following will always be correct CPA, TCPA as it is relative to you
• Any trial manoeuvre will be incorrect
• Platform stabilisation - heavy weather, pitching and yachting around means poor input
• Target Glint - Hitting different parts of the oil rig making it appear to be moving (Interference effects in the radar scattering from extended unresolved targets leading to a “glint problem”)

Question 11

What are the performance standard / criteria for ARPA?

Answer 11

• Within 1 minute + Track + CPA + TCPA
• Within 3 minutes + Full report + CPA to within 0.3 of a nautical mile + TCPA
• Bearing discrimination and Range discrimination cause a problem for ARPA due to target swap

Question 12

When taking over a watch, what would you with your radar?

Answer 12

• Put the controls to zero and reset the radar to how you want it
• Also on a regular basis should do a performance monitor check - Checks the magnetron on the radar and ensure that it is working to within a specification as the manufacturers instructions. Log in deck logbook
  
  • Go into a menu on the radar and select. Opens up a voice box on the wave guide and paints on the radar a plume or concentric rings. Measure the length of those rings and it will tell you if its working properly
• Once taken over the watch, re-plot the position, setup all of the radar equipment to optimum performance, this will include setting up the radar, starting from scratch, ECDIS ensuring that all the layers displayed are the ones that you want to have.

Question 13

How do you setup a radar?

Answer 13

• Check no open PTW, no one aloft, visual check, no halyards in the way
• Turn it on and turn all controls to zero
• Adjust in the following order: BGTC (Big Girls Talk Crap) (Brilliance, Gain, Tune and Clutter)
  
  • Brilliance - is for ambient light
  • Gain - turn up until speckling effect and then turn back slightly
  • Tune - tune for best picture. Look for targets on outer edge of radar and tune to get best return for those targets. If no targets, then set to maximum deflection on the tuning bar.
  • Clutter - Sea and Rain. (Affects the radar from the centre outwards) When adjusting the sea clutter we are trying to get rid of the burnt area in the middle of the screen. Rain clutter suppresses over the whole screen and can also suppress small targets which is a danger. When searching through a rain cloud you should turn rain clutter on and then off again .

Question 14

ECDIS What are the advantages and disadvantages of rastor charts - RNC’s

Answer 14

Advantages:

• Exact copy of a paper chart
• Familiarity in look and symbology
• Good topographical detail
• Cheaper to produce
• World wide coverage

Disadvantages:

• Can’t interrogate
• Cannot be customised
• Cannot zoom in, chart become pixilated
• Large file sizes
• Not seamless. need to load another chart if going off “edge”

Question 15

ECDIS What are the advantages and disadvantages of Vector Charts - ENC’s

Answer 15

Advantages:

• Charts may be rotated to any angle
• File sizes up to 10 times smaller than RNCs
• useful for correcting - easily downloaded via internet
• Objects can be interrogated
• Chart data may be shared with other equipment i.e. radar, AIS
• You can zoom in and it is seamless - Layering eg. CATZOG when passage planning (Category zone of confidence)

Disadvantages:

• Technically more complex
• More expensive
• Not worldwide coverage
• Teaching and training takes longer and more expensive
• Objects need to be interrogated to get information

Question 16

What are the display options for ECDIS?

Answer 16

Chart objects and information available for display are sub-divided into three categories:

• Base display; Lowest chart display (minimal information) can be used for passage planning, however lack of navigational and safety information
• Standard display; as defined in the ECDIS Performance Standards, does not necessarily display all the chart objects necessary for safe navigation under all circumstances, e.g. Spot soundings, Underwater obstructions.
• All other information; i.e the above mentioned spot soundsing and underwater obstructions.

Horizontal Datum for ENCs is WGS84

Question 17

Which resolution sets out the performance standards for ECDIS

Answer 17

IMO Resolution A.817(19) = Which covers five areas

1. Route Planning
2. Definitions
3. Chart Updating
4. Nav Input
5. Ergonomics

Question 18

Additional ECDIS information:

Answer 18

• An IMO accepted back up system for primary ECDIS is a 2nd ECDIS or full UTD corrected paper charts
• A feature that distinguishes ECDIS from ECS is that it fulfils the IMO Performance Standards - IHO S-52 Specification for Chart Content and Display Aspects of ECDIS - IHO S-57 = IHO Transfer Standards for Digital Hydrographic Data - ARCS = Admiralty Rastor Chart Service - You would use RCDS mode when there is not adequate ENC coverage for the area you are in.
• When operating in RCDS mode you need an UTD folio of paper charts as a back up

Question 19

Define safety contours with regards to ECDIS

Answer 19

A line joining equal depths. We can chose what depth and what colour with an ENC. Can have a deep contour and a shallow contour which can give us indications on channels

Question 20

Define Safety Depths with regards to ECDIS

Answer 20

• Where we chose a depth that we get the system to alarm at and take into consideration our draught and UKC required, also height of tide
• Will be displayed as a cone in front of the ship which scans ahead and will tell us that we are running into shallow water / danger

Question 21

Gyro Compass Checks
Pre Departure

Answer 21

The performance of a ll magnetic compasses, including spares should be checked as follows:

• Freedom of movement of the gimbal
• Card floating freely, level and rotating without any friction
• Liquid free of bubbles and clear
• Compass card clear and sharp (Able to read) with no distortions
• Optical system (if any correctly adjusted and clean)
• No liquid leaks around seals or filler plugs

Question 22

Gyro Compass Checks
Pre Departure

Answer 22

Operational checks

• Check the gymbal is moving freely
• Check the compass card is clear and sharp
• Card should float freely and rotate without any friction
• Check the liquid is free of bubbles and clear
• No liquid leaks around seals or filler plug

Question 23

Compasses - Performance Monitoring

Answer 23

Monitoring Performance of compasses

• Record compass deviations in the ‘Compass Deviation Book’
  
  • Take a compass error after every large alteration of course
  • Record a compass error at least once a watch
• The purpose of taking a compsas error is to identify any excessive deviations, which may indicate the need for repair.

Question 24

Testing Steering

Answer 24

• Test manual steering at least once a day and before entering restricted waters.
• Test steering gear at least twelve hours before departure. If vessel is on regular short voyages, this may be done once a week
• Log all steering gear tests, check and emergency steering drills in the Official Logbook.
• Perform an ermergency steering gear drill every three months. (Emergency steering gear drill within 24 hours of entry to the USA)

Question 25

**AIS - Do's and Don'ts**

Answer 25

* Excellent for **situational awareness** * Is an **AID to navigation** * **Not** to be used directly for collision avoidance * GPS - Ground Stabilised - * CPA and TCPA between two GPS recievers... not ships * Compass heading which gives you **aspect** * Which way the vessel is pointing and which way it is going * Rate of Turn, COG, SOG, Heading and position