Radar and Bridge Equipment Flashcards
1
Q
RADAR Essentials
A
- 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
2
Q
Radar Pre Depature Checks:
A
- 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
- VRM Checked again range rings
- 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.
3
Q
How would you setup your X-Band Radar when navigating a coastal passage plan 6NM from Land?
A
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
4
Q
How would you setup your S-Band radar when navigating a coastal passage 6NM from land?
A
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.
5
Q
What must be posted on the bridge with regards to Radar and Navigation?
A
- 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
6
Q
What 3 different types of information does AIS show?
A
- Static
a. Length
b. Breadth
c. Call sign
d. MMSI
e. Type of ship - Dynamic
a. Course, speed of vessels and own vessel (GPS fed) - Voyage Data
a. Draught
b. Number of People
c. Destination and ETA
d. Navigational Status
7
Q
NAVTEX - 518 kHz
A
- 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
8
Q
BNWAS
A
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)
9
Q
What is ARPA
A
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
10
Q
What are the errors of ARPA?
A
- 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”)
11
Q
What are the performance standard / criteria for ARPA?
A
- 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
12
Q
When taking over a watch, what would you with your radar?
A
- 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.
13
Q
How do you setup a radar?
A
- 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 .
14
Q
ECDIS What are the advantages and disadvantages of rastor charts - RNC’s
A
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”
15
Q
ECDIS What are the advantages and disadvantages of Vector Charts - ENC’s
A
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
