Nav & Radar MCA 100 past questions Flashcards
(102 cards)
1
Q
List 5 Nautical publications needed for passage planning. And what they contain
A
- Chart Catalogue. Starting point for passage planning. Gives full details of charts and publications needed for your voyage in a world wide inventory
- Ocean Passages of the World. Used for ocean passages detailing weather, currents, ice, hazards and distance between major ports
- Mariners Handbook. Can be used as a guide to improve understanding of metrology, Navigation and regulations.
- Admiralty Sailing Directions
- Admiralty List of Radio Signals. Provides all information on all aspects of maritime radio.
- Admiralty List of Lights and Fog Signals
- Routeing Charts. Wind direction + speed, ocean currents, sea + air temperatures, air pressure and frequency of storms.
- Tidal Stream Atlas. Used to predict direction and speed of tidal currents
- Notices to Mariners. Corrections to nautical charts and publications
2
Q
What are the benefits of ARPA?
A
- Reduces workload
- assist with data interpretation; target tracking is automatic.
- Provides continuously updated info and rapid situation evaluation
- should, if used correctly, reduce the risk of collision.
3
Q
List six things ARPA must show.
A
- Range of Target
- Bearing of target
- Predicted CPA
- Predicted TCPA
- True Speed
4
Q
List 5 ECDIS alarms.
A
- Crossing safety Contor
- Approach to a critical point
- Deviation from route
- Position system failure
- Different geodetic data
5
Q
5 ECDIS warning indicators?
A
- Default safety contour
- Information over scale
- Larger-scale ENC available
- No ENC available
- System test failure
- Area with special conditions
6
Q
Describe spring tides and Neap tides
A
- Spring tide is when the planetary bodies are in alignment. Giving higher high tides and lower low tides.
- Neap tides are when the planetary bodies are not in alignment. Causing lower high tides and higher low tides
7
Q
What’s the difference between relative and true motion radar display?
A
- Relative motion is the standard default display. Shows relative vectors. Good for collision avoidance.
- True motion shows true vectors of vessels. Shows true heading of targets
8
Q
What’s the difference between RCDS, ECDIS and ENC
A
- ECDIS is a highly sophisticated nav system that meets IHO and IMO standards for navigation.
- ENC is a vector chart data produced by the national hydrographic office that does not meets IMO and IHO standards
- RCDS = Rasta chart display system is a scanned paper chart. It’s a mode of operation in ECDIS
9
Q
What factors should be taken into account when determining safe speed?
V
D
Makes
Little
Willie’s
Drips
A
- state of Visibility.
- the traffic density, including the concentration of fishing vessels and other vessels.
- manoeuvrability of the vessel.
- at night, the presence of background light.
- weather. The state of wind, sea and current and proximity of nav hazards.
- Draft of the vessel.
10
Q
Safe speed part 2 - What are the additional factors with the operation of a radar to take into account?
Charlie
Can’t
Eat
Pie
No
More
A
- The characteristics, efficiency and limitations of the radar
- Any Constraints imposed by the radar ranges scale in use
- Effects on the radar detection of sea state, weather and other sources of interference.
- The possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range.
- The number, location and movement of vessels detected.
- More exact assessment of the visibility may be possible.
11
Q
What are the four stages of passage planning?
A
Appraisal - gather information about the passage. Charts and publications needed for the route.
Planning - identify all the danger areas, hazards, intended track from berth to berth, Safest and fastest route, waypoints reporting points and PI. Record the plan in the bridge notebook.
Execution - briefing the bridge team in the passage plan and navigating the ship accordingly. Berthing and logistical information, environmental factors, ETA’s at critical points considered.
Monitoring - checking progress of the ship against the passage plan. Navigation equipment checked regularly as well as any changes amended and compliance with IRPCS and MARPOL regulations.
12
Q
What compulsory Inputs are needed for ECDIS?
A
- GPS
- Speed Log
- Gyro Compass
13
Q
What are the Advantages and disadvantages of ENC?
A
Advantages
- Alarms
- Easy to update
- Set contours and safety depths
- Display orientation. set north up or course up
-Smaller files
-Layers of information
- Zoom in and out and symbols stay the same
Disadvantages:
- Cost
- Hidden information
- Limited coverage worldwide
14
Q
What RCDS pros and cons?
A
Pros:
- worldwide coverage
- affordable
-similar to Pape charts
Cons
- No alarms
- No customisation
- Large files
- Small Zoom
- expensive to correct
- When you change charts, you need to check you are using the correct datum
15
Q
Principles of an Echo Sounder
A
- Transducer sends a pulse of sound to the sea floor at 1500m per second
- Return pulse moves coils and creates voltage. The time interval between them is calculated
- Depth processed and displayed
- Depth = velocity x time/2
16
Q
What are multiple echos on an Echo sounder?
A
- Multiple echos may bounce between the hull and sea bed a number of times at each return; some of the energy can be detected. Most noticeable in shallow water
17
Q
Echo Sounder Errors
A
- False echos
- Cone effect
- Side reflection - side lobes from embankments
- Aeration - air bubbles
- Propagation - speed that sound travels through water changes with temperature and salinity
- Noise
- Pythagoras - when TX and RX are not in a single transducer
18
Q
What are the two standard frequencies for an echo sounder?
A
- 200 KHz - shallow, narrow cone, defined image
- 50 KHz - deep, wide cone, less defined
19
Q
What’s the Principle behind GPS?
A
- A satellite generates a radio wave signal at the speed of light with accurate time stamp
- At the same time a GPS receiver generates identical code and compares time difference upon receiving the signal
- A range is then calculated
- Range = Speed of light x Time
20
Q
What are the three main components of GPS?
A
Space segment - consists of 24 satellites and six spares. There should be a minimum of 4 satellites at all times
Control segment - a series of worldwide ground control stations for monitoring and tracking.
User Segment - The user segment only receives. (You on the boat)
21
Q
What’s differential GPS (DGPS)
A
Uses bases with a fixed known position to adjust real time GPS signals to eliminate errors
- Base station receives signal from GPS
- Calculate the error from a known position.
- Works out time error and sends it to users
22
Q
Define DOP.
A
Dilution of Precious is a way to measure the quality of the GPS fix. Dop 1 indicates a good fix, and Dop 4 indicates a poor one.
23
Q
What is HDOP?
A
Horizontal Dilution of Position: gives you Lat and long and is needed for the position
24
Q
List five GPS errors.
A
- Ionosphere error: caused by ironized partials in the upper atmosphere that can slow the signal down.
- Troposphere error: caused by weather.
- Multi-path error: caused by mountains, buildings, and bridges can cause the signal to reflect.
- Sat clock error: accurate time on board is essential.
- Receiver noise: interference from radio transmission can affect the signal
25
Explain Geo datum and datum shift?
- Geo Datum is a mathematical model of the surface of the earth.
- Datum shift is the distance to move a fix rendered to WGS84 to place it on a chart correctly.
26
What's the difference between true motion and relative motion?
- True motion displays the actual vectors of the target and observing vessel.
- Relative motion display portrays the motion of the target relative to the motion of the observing vessel
27
How does a Doppler Log work?
The Doppler log transmits an acoustic sound through the water at a 60-degree angle. The horizontal signal that is reflected will have a higher frequency the faster the vessel moves forward and a lower frequency the slower it goes. This is a Doppler shift and can be converted to speed.
28
What are the Advantages of a Doppler Log over an Electromagnetic Log?
- Yields STW and SOG
- Not susceptible to hull shape irregularities
- Better in pitching and rolling
- Better at speed, berthing and reversing
- No moving parts
- Highly accurate
29
How does the Doppler log overcome pitching and rolling?
Janus Configuration - Has two transducers, one facing forward and one aft about 60 degrees. The effect is to cancel errors when pitching and rolling.
30
What should you do when approaching restricted visibility?
- Inform the master
- Increase lookouts
- Appropriate nav lights
- Appropriate sound signals
- Fix position
- Reduce to safe speed
- Engines on standby
- Radar plotting
- VHF 16 and 13
- Hand steering
31
What are the Advantages of a Doppler log over an EM log?
- Yields STW as well as SOG.
- Not susceptible to hull shape irregularities.
- Better in pitching and rolling.
- More resistant to fouling and aeration.
- Better at low speed and berthing/ reversing.
32
What are 4 Doppler Log errors?
- Propagation speed determined my sea temperature and salinity.
- Damaged unit.
- Heavy pitching and rolling.
- Aeration caused by engines and thrusters.
33
What are the types of marks used in the IALA buoyage system?
- Safe water marks
- Isolated danger marks
- Special markers
- Cardinal marks
- Lateral marks
- Emergency wreck marks
34
What's the difference between IALA A and B?
The two systems are the same, except that the colours of the lateral marks are reversed. CAN always on PORT and CONE always on STARBOARD.
35
How do you reduce the errors caused by deviation?
Permanent magnetism - Longitudinal and athwartship magnets are placed inside the compass binnacle
Induced Magnetism - Soft iron spheres (Kelvins balls) and flinders bar magnets are used
36
What is deviation?
The ship's metals and iron cause the compass needle to deviate from magnetic north. The angular difference is called deviation.
37
Pros and cons of X-band radar?
- Better range and bearing discrimination
- Better at picking up targets
- Picks up SARTs
- 3cm beam width
- 10 GHz frequency
- More sea clutter response
- Not good in precipitation
- Not good for long-range
38
Pros and cons of S-Band Radar
- Better in bad weather
- Better for long range
- 10cm wavelength
- 3GHz Frequency
- Doesn't pick up Sarts
- Poor range and bearing discrimination.
39
What is sea clutter?
Sea clutter suppresses gain in the centre of the radar. It never extends the whole range. Reducing effects out to 4 to 6NM
40
How does Rain clutter work?
- It acts on the echo by trying to cut off the trailing edges so that just the leading edge is seen. Applies this to the whole range of display
41
What are the factors involved in installing an echo sounder transducer?
- Should be as deep as possible to reduce aeration
- Should be as far away as possible from sources of noise
- On centre line
- Usually on forward half of ship
- Slight projection from the hull
42
Echo Sounder Errors
- Propagation due to water layers of different temperatures and saline content
- Areation from the bubbles caused by the ship hull and props
- Cone effect from width of pulse
- Multi-echos due to signal bouncing
- Noise errors from other sources
- Side reflection from side lobes bouncing off channel embankments
43
How to set up the radar?
C- Check
T-Turn on
T-tasty
B-big
R-Randy
P-pink
G-girls
T-take
C-cock
- Check scanner is clear before turning it on
- Main power
- All controls switched down to the minimum
- Set appropriate range
- Adjust Brilliance
- Gain control light speckle background
- Tune
- Sea clutter
- Rain clutter
44
What are the five factors affecting the reflective properties of targets?
M.A.S.T.S
- Material the vessel is made out of
- Aspect of target
- Size of vessel
- the texture of the surface
- Shape of target
45
What are side lobes?
- side lobes are the escape of energy near the scanner. draw a picture to highlight
46
Describe Horizontal beam width.
- The x band has a 3cm beam width and an S-band of 10cm.
The narrower the beam, the better the definition.
- gives better bearing discrimination. see picture
47
What are the factors determining the practical detection range of the radar?
- the height of the scanner
- height and reflective properties of targets
- Atmospheric conditions
- pulse length
48
Three main factors that affect minimum detection range?
- the height of the scanner
- pulse length
- wider vertical beam
49
Explain Range discrimination and Bearing discrimination.
- Range discrimination is the ability of the radar to differentiate between 2 targets on the same bearing bit and different ranges.
- Bearing discrimination is when two targets are at the same range but on different bearings
50
What's the function of the ground segment?
- control/monitoring stations
- check the quality and integrity of the GPS signals
- correct clock error
- Measure the satellite orbital positions
- gives navigation formulary to upload every 8 hours
51
state information contained within each Navigation message sent by GPS satellites
- Sat ID pseudo code
- almanic data
- ephemeris date clock information to calculate range
52
Weekly Notice to Mariners: what does this include?
E-every
S-sailor
N-navigates
S-sailing
L-lights
R-round
M-miscellaneous
D-dark
•Explanatory Notes publication list.
•Updates to standard Nautical Charts.
•Reprint of NAVAREA 1 nav warnings.
•Updates to ADMIRALTY sailing directions.
•Updates to the ADMIRALTY list of lights and fog signals.
•Updates to the admiralty list of radio signals
•Updates to miscellaneous ADMIRALTY Nautical publications.
•Updates to ADMIRALTY digital services.
53
Procedure to update Notice to Mariners
Check the publication list for charts affected.
Locate the chart correction in section II.
Check the chart edition onboard is the latest and that the correction has been done.
Do corrections on the charts.
Record corrections at the bottom left hand corner of chart.
Record the correction in the correction log.
54
What are the Advantages of AIS?
- can enhance radar and Collison avoidance
- gives names and call signs to radar targets
- may indicate targets invisible to radar
- May clarify target intentions
55
Class A data broadcast by AIS
☆ Static data
- Every 6 minutes
- MMSI / IMO number
- Dimensions
- Type of ship
- Call sign
- Ships name
☆ Dynamic data
- every 2 seconds to 3 minutes
- position lat and long
- timestamp
- course and speed over ground
- true heading
- the rate of turn
☆ Voyage
- every 6 minutes
- Draught
- Denstination and ETA
- Hazardous cargo type
- Any Saftey messages
56
What does Ground stabilized show?
- Vessel moves with the tide when stationary
- SOG + COG
- trail = ground track
- Ground stabilization should not be used for collision avoidance
57
what does Sea Stabilized show
- Targets stationary on display
- Trails= water track
- land moves contrary to the tide.
58
pros and cons of ENC (ecdis)
pros
- set alarms
- easy to update
- customisable
- zoom in and out symbols stay the same
- layers of information
- set contours and safety depths
cons
- expensive
- limited coverage
- hidden information
59
RNC pros and cons ( Raster)
Pros
- Worldwide coverage
- affordable
- similar to paper charts
cons
- no alarms
- no customisation
- large files
- small zoom
- expensive to correct
60
What's LAT
- Lowest Astronomical tide: also known as chart datum. the lowest level of water ever expected.
61
What's HAT?
Highest Astronomical tide= MHWS. The highest level of water is expected. Used for clearance under bridges and power cables
62
What's the drying height
shows the height of an object such as Rocks or shoreline above chart datum
63
Choosing objects for Paralled indexing (P.I. lines)
- fixed on the chart
- bold and conspicuous stand out on the general coastline
- on the beam rather than ahead
- 3NM range scale pilotage waters
64
What's multiple echos on echo sounded
more common in shallow water. the sound energy is reflected off the sea bottom and may re-reflect off the hull and you get multiple echoes as the signal bounces between the hull and the seabed.
65
List 5 GPS ERRORS
- ionosphere error caused by the earth's upper atmosphere. Ionised particles slow down the signal.
- Tropospheric error caused in the lower earth's atmosphere.
- multipath error caused by building bridges and mountains can reflect signals.
- Satellite clock error, need accurate time on board for timing and ranging.
- receiver noise: interference radio transmission can cause small error
66
what's Geo datum or horizontal datum.
- Horizontal Datum is a mathematical model of the surface of the earth
- base reference system for lat and long
67
What's datum shift?
Datum shift is the distance and direction from wgs84 to place correctly on a chart.
68
What are the errors with an echo sounder?
- Cone effect
- Propagation errors - change in speed due to different densities of water
- Aeration caused by bubbles from the hull.
- Cavitation - the disturbance from the engines and thruster
- Multi echo
- Side reflection
- Noise error
- Pythagoras error
- Spurious returns
69
When comparing depths on the charts and display, what corrections should be applied to the sounder?
- Offset to show DBK
- Draught
- HOT
70
What are five reasons to get the compass adjusted?
- First installed
- becomes unreliable
- ship undergoes major repairs that could affect permanent and induced magnetism.
- New electrical or magnetic equipment installed near the compass
- after two years since the last one
- compass shows defect
- any damage to vessel
- after a fire
71
What is in standard display ECDIS
- Display base
- drying lines
- indication of fixed and floating nav aids
- boundaries of fairways, channels
- prohibited and restricted areas
- chart scale boundaries
- indicators and caution notes
- ship and ferry routes
72
How can the radar overlay confirm the correct input?
- matching charted features, an offset would indicate a GPS error
- rotation would indicate heading input error
73
How do you correct permanent and induced magnetism?
- To reduce permanent magnetism you use fore and aft longitudinal magnets and Athwartsship magnets are placed to counter the ship magnetism.
Soft irons spheres and finders bars are used to counter the induced magnetism.
74
Three methods to work out compass error?
- transit bearing
- bearing to terrestrial body from known position
- bearing to a celestial body
75
How do you work out compass errors using transit?
- choose two charted objects that form a good transit.
- hold transit a head or astern
- Measure true bearings on the chart
- the difference is the compass error
76
What's deviation
The metals and irons on the ship cause the compass needle to deviate the angular difference where the needle sits, and magnetic north is called deviation.
77
What are the carriage requirements for paper charts for each ECDIS, Raster
- Ecdis you need a Duke system that's run off an independent power source. if not, paper charts are required.
- Raster charts: you need paper charts
78
What speed is needed for ARPA
Speed through the water is needed for collision avoidance.
79
What is the Doppler effect?
The change in frequency or wavelength of a wave for an observer who is moving relative to the wave source
80
What's the principle of a Doppler log
- doppler log uses Doppler shift to calculate speed through the water
81
pros and cons of Doppler log
- most accurate
- can measure speed ahead and astern
- can be used for ocean navigation and berthing
- measures SOG and STW
cons
- affected by pitching and rolling
- The location of the sensor can affect the quality of the reading
- not good in shallow water
- affected by Aeration
82
setting up echo sounder
- set range
- set alarms
- set gain
83
What's in the ECDIS base display?
- Coastline
- ships saftey contors
- indication of isolated underwater dangers
- indication of isolated dangers
- traffic touting schemes
- scale range orientation
- units of depth and height
84
The standard display on ECDIS shows?
- spot sounding
- submarine cables
- ferry routes
- isolated dangers
-details of Nav aids
- the content of cautionary notes
- ENC edition data
- Geodetic datum
- magnetic variation
- place names
85
Three advantages of AIS
- it can see around corners
- can see through sea clutter
- path prediction
86
Why shouldn't you rely on AIS for collision avoidance?
Information provided from other vessel instruments.
87
Before plotting the GPS position on the chart, what should you do?
Check if the chart is wgs84 and can be plotted directly onto it. Check chart notes for the datum shift.
88
Procedure to update charts?
- receive WNM
- check the publications list for charts affected
- check if the edition on board is the lasted
-do corrections on the chart
- record the correct bottom LH corner of the chart and in the corrections log
89
What 2-speed logs measure SOG?
- GPS log
- doppler log
90
State the wavelength for x band and s band radar.
x band 3cm 9 Ghz
s band 10cm 3Ghz
91
false echos on a radar
- radar pulse bounces off obstacles on its ship before hitting a target.
- Radar thinks the target is in the direction of the radar
92
State how you can show maritime safety information ( MSI) on ECDIS
Enter information on the chart in the appropriate place using Mariners notes.
93
Three factors while setting up safety contours
- draft of the vessel
- UKC
- the height of the tide
94
How do you determine safety depth?
Draft + squat + ukc - HOT
95
fish shoal errors
May interfere with bottom return readings or interfere with regular readings
96
What's the difference between ECDIS and ENC
Ecdis is the hardware, and ENC is the database. All are approved by the IHO and IMO.
97
Radar overlay is helpful for?
- verifying the location of fixed targets' land or navigation marks
- checking inputs are working correctly GPS there is no offset, and the heading is aligned for the compass
98
Three ways to update ECDIS
- disk or USB sent from the supplier
- download updates from nominated server
- email download
99
Rule 5
Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
100
Rule 6
Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.
101
Rule 19
(Conduct of vessels in restricted visibility)
(a) This Rule applies to vessels not in sight of one another when navigating in or near an area of restricted visibility.
(b) Every vessel shall proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines ready for immediate manoeuvre.
(c) Every vessel shall have due regard to the prevailing circumstances and conditions of restricted visibility when complying with the Rules of Section I of this Part.
(d) A vessel which detects by radar alone the presence of another vessel shall determine if a close-quarters situation is developing and/or risk of collision exists. If so, she shall take avoiding action in ample time, provided that when such action consists of an alteration of course, so far as possible the following shall be avoided:
(i) an alteration
(i) an alteration of course to port for a vessel forwards of the beam, other than for a vessel being overtaken;
(ii) an alteration of course towards a vessel abeam or abaft the beam.
(e) Except where it has been determined that a risk of collision does not exist, every vessel which hears apparently forwards of her beam the fog signal of another vessel, or which cannot avoid a close-quarters situation with another vessel forwards of her beam, shall reduce her speed to the minimum at which she can be kept on her course. She shall if necessary take all her way off and in any event navigate with extreme caution until danger of collision is over.
102
- Explanatory Notes publication list.
-Up dates to standard Nautical Charts.
-Reprint of NAVAREA 1 nav warnings.
- Updates to ADMIRALTY sailing directions.
- Updates to the ADMIRALTY list of lights and fog signals.
- Updates to the admiralty list of radio signals
-Updates to miscellaneous ADMIRALTY Nautical publications.
-Updates to ADMIRALTY digital services.
