Bridge Nav Equipment Flashcards
Navigational equipment Required for a vessel 2999GT?
Magnetic Compass
Gyro Compass
Means of taking a bearing
Echo sounder
GPS
LOG
Rudder angle indicator
Radar, both 3 and 9 (what?)
ECDIS
AIS
Signaling lamp
Met Instruments
Search light
EPIRB
SART
BNWAS
LRIT
What does ‘Meet Her’ to the Helmsman mean
Check the Vessels head from swinging in a turn
SOLAS, when adopted and put into Force?
How many chapters?
Latest version adopted 1974, into force 1980
1st version in 1914
Currently 14 chapters
Aim of SOLAS
The main objective of the SOLAS Convention is to specify minimum standards for the construction, equipment and operation of ships, compatible with their safety. Flag States are responsible for ensuring that ships under their flag comply with its requirements
What is SOLAS chapter V?
Safety of navigation
SOLAS Chapter V Regulation 19?
REGULATION 19 - Carriage requirements for shipborne navigational
systems and equipment
How would you physically/visually check your compass before departure?
Free Movement of the Gimbal
Card floating freely, level and no friction
Liquid free of bubbles and clear
Compass card clear and easy to read, no distortion
Optical system (if fitted, eg Mirrors) clean and correctly adjusted
No liquid leaks
No tools or electronic/magnetic equipment nearby
When should the compass be adjusted? (Swung)
When 1st installed
Every 2 years since the last alteration if a record of deviations has not been maintained, or if the deviation becomes excessive
When it becomes unreliable
Ship undergoes structural repairs or alterations
Electrical equipment near the compass is added, removed or altered
collision
visable defects in the compass
Major change of latitude
How are permanent and induced deviation corrected
Induced - By Kelvins Balls and Flinders Bar (Soft Iron)
Permanent - by for/Aft and Athwartships corrector magnets
And heeling corrector magnet tube (vertical)
Which equipment gets an input from the Gyro
Autopilot
Ecdis
Radar
Sat-C
Vsat
Main advantages of the Gyro over the magnetic
Find True north by the earths rotation, which is more useful than magnetic north
They are not affected by metal or other sources of magnetic deviation
Hence Gyro bearings can be plotted directly onto the chart
Types of Gyro Error?
Latitude error,
SOG Error
Gyro drift
Citation needed
Ways of visually taking a bearing
Hand bearing compass
Azimuth circle - Sits on top of a fixed compass
Azimuth Mirror - also sits on top, does celestial objects too
Pelorus Compass - Not a real compass, rotate the card to line it up with ships head, can then take bearings from it. Can be set up to give true or relative bearings. Portable
What does Azimuth mean
Fred ‘bearing of’
The horizontal angle measured from North
How to use a Azimuth Mirror
Sits on top of a compass, for terrestrial or Celestial objects
Turn the Prism down to look at terrestrial objects on the surface
Look accross the top like a regular compass
Or
Turn the Prism up, to see the reflection of Celestial objects in the sky
See the reflected object and the bearing at the same time
How to check the Gyro Compass in sight of land
Find a Transit between 2 fixed points, eg edges of 2 islands
Take the bearing, using the Azimuth Mirror/Circle, and compare to the True bearing on the chart.
The difference, if any, is the Gyro error, eg 2ºL. on any bearing
How to check the Magnetic Compass in sight of Land
Steer a constant heading, make note of the heading
find a transit, and take a bearing using the Pelorus
The bearing will be a C, The charted bearing will be T
Account for Variation, the remaining difference will be Deviation
Compare to deviation card to check if deviation has changed for that HEADING
How to use one bearing to check a compass
From a fixed position
Either alongside the dock, or from a HSA (the most accurate fix)
Compare the bearing to the true one to find error
when are bearings of the sun at sunrise/set taken
When the Sun is half a diameter above the horizon
Citation needed
What is an Amplitude?
A true Azimuth (Bearing) of the sun ar Rising or Setting
What is Declination, where do we get it from
The angle North or South of the Sun for that day. 0º at equinox, 23º at Solstice
Same all over the world, Found in the Daily pages of the Nautical Almanac
How to check the Gyro out at sea?
With an amplitude of the Sun/ True azimuth of the Sun at Rising or Setting
Lookup DECLINATION for that time of day in the Nautical almanac
Note our LATITUDE
Use Norries tables to get the True bearing for that latitude and declination
Convert True bearing for N/S declination, E/W rising setting (0+, 180- etc)
Compare to check for compass error
MGN 610 is?
What does it say about compass checking?
Guidance on the Merchant Shipping (Safety of Navigation) regulations 2020
Which implements SOLAS V safety of navigation
-A compass should be checked at least one per watch
And after every major course alteration
Different methods of checking a compass
Transit
Amplitude
True Azimuth of a heavanly body
with a single bearing from a fixed position
How to do a True Azimuth of a heavenly body
Use Azimuth mirror, take a bearing, easiest is the Sun. On the Hour
Use the Nautical Almanac, get the GHA and Declination for that hour
Adjust for longditude, to get LHA
Use the sight reduction tables with LHA, latitude, declination
To get the Zenith or true Azimuth
Compare to your compass for error
What is the GHA and LHA
Greenwich Hour Angle
The bearing from London to any heavenly body
Local Hour Angle
The angle from our position E/W of Greenwich, to any heavenly body
LHA = GHA +/- our Longditude
West - , East +
What makes Solas part of uk Law
Where do we get guidance on it
The merchant shipping Regulations (Safety of Navigation) 2020
MGN 610
What HDOP value is considered poor
5 or larger
Common errors for a GNSS system
Solar Activity
Jamming/Spoofing
Tropospheric error - difference in humidity, pressure, temperature in the lowest level of earths atmosphere interfering with the signal
Satellite Orbit error
Satellite Clock error
Multipath Error
How to monitor the accuracy of your gps underway?
Monitoring the integrity of the GPS is crucial to ensure thereliabiltty of navigation and positioning data. I would achieve this by;
1. Verify the number of satellites in view, minimum 4, but ideally 6 for a more accurate fix
2. Check DOP value, The lower the value the better, more than 5 is poor/unreliable
3. Cross reference with other navigation methods
4. Observe for sudden drops in accuracy changes
5. Use a GPS with WAAS/EGNOS support
6. Keep the GPS updated to latest software
7. Understand GPS limitations, accuracy can be affected by factors such as atmospheric conditions. Do not soly rely on GPS
How can GPS corrections be transmitted to the users device
GBAS Ground Based Augmentation System.
Transmitted on MF, limited range to the local area
Full list of stations transmitting listed in ADMIRALTY List of Radio Signals Volume 2
SBAS Space Based Augmentation System.
Transmitted by Geosationary satellites over a region or country
Such as the US WAAS, or European EGNOS system
(Wide Area Augmentation System)
(European Geostationary Navigation Overlay Service)
Where could You find details of the performance standards of GPS?
What are some of them
Resolution MSC.74 1998
Performance Standards for shipborne combined GPS/Glonass reciever equipment
Includes:
Position accuracy should be less than 35m, or less than 10m in Differential mode with a HDOP value of less than 4
Is capable of acquiring the required accuracy within 5 minutes, when there is valid Almanac data ??
Be capabale of re-acquiring the desired accuracy in 2 minutes afer a 60 second power outage
Output a new position solution at least every second
Give a warning if HDOP value is greater than a set value
What is a sound reception system?
Vessels with a totally enclosed bridge, should be fitted with one
designed to ‘hear’ fog signals and display them and their direction digitally to the OOW
What is a signaling lamp used for? what is the difference between it and a manouevering lamp
flashing morse code messages, directional
manouevering lamp is all round white light, with a range of 5 miles. R34
How often should the Echo sounder be checked
Tested against the leadline;
Anually
On completion of a refit
When any part of the equipment is changed
When there is any doubt about the accuracy
Errors on the echo sounder can be caused by:
iNCORRECT SETUP - depth/offset of transducer not input correctly
soft bottom, mud can give poor return
Fish
water layers of differenct temperature/salinity
Seaweed/ silt
Side echoes in narrow channels
multiple echoes,
What is the speed of sound in water?
and light?
Sound 1500m/s
Light 300,000 km/s (300 million m/s)
What you do if the echo sounder and the Ecdis dont agree?
Stop the vessel
Call the master
Confirm the position by other means
APEM to safety
Types of Water Log
Impeller log - paddle wheel
Pitot-static Tube
Electromagnetic - Current through coil, detects water moving past
Doppler - Can give SOG and STW, important for radar stabilisation
IMO RESOLUTION A.526(13) sets what?
Performance standards for Rate of Turn Indicators
3 key points?
Performance standards for Rate of Turn Indicators
* The ROTI should be ready for operation and within 4 minutes of being switched on.
* The design should be such that the breakdown of the ROTI will not degrade the
performance of any other equipment to which it is connected.
* The ROTI should include a means of enabling the operator to verify that it is
operating
VDR?, records what
Audio on the bridge
Inputs from all sensors
Subject to an annual inspection
black box, helps identify the cause of any accident
MGN 610?
MGN 610 Provides clarification and guidance on the UK law; Merchant Shipping Regulations 2020 (Safety of Navigation)
The law itself is based on SOLAS Chapter V
Where are both Gyro and magnetic compasses unreliable?
At the poles, or very high latitudes
What is on the Deviation Card
Date and location of Swinging
Name, CoC and Signature of adjuster
Name and signature of Master
Location of corrector magnets; transverse, longitudinal,
residual coefficients
Residual deviation
Heeling Magnet
Flinders bar
What is retention Error?
In a magnetic compass
If the Ship is on the same heading for several days, or sat in port for a long time.
The Ship will retain some of the induced magnetism for a period of time
This can cause some error, a short shakedown, with the ship on other headings should remove this
How often do you check the compass underway?
After every major course alteration
and at least once per watch if there have been no alterations
What is a TMC or THI
Transmitting Magnetic Compass and Transmitting Heading Indicator
Both use magnetic sensors to determine the ships heading and transmit this info via AIS
Which properties are the basis for a gyroscopes behaviour
Gyroscopic Inertia-causes it to maintain its position in space regardless of how the base is moved
Presession- if you attempt to tilt the gyro, it will instead move perpendicularly to the applied force
How to Service a gyro compass
Follow manufacturers guidelines. Sperry Marine for example recommends regular maintenance every 18 months, and exchanging the centering pin evry 5 years by authorised personnel
How to perform routine operational checks on a Gyro
Regular visual checks for damage, loose cables etc
calibrated to True North regularly, and after alteration, change in location
Regular checks for errors should be made and recorded. Corrected via calibration or adjustment
Clean and lubricated
Power supply is reliable and UPS is available
What is AIS
What is its Range?
Automatic Identification System
AIS is a maritime mobile VHF broadcast system that sends dynamic, Voyage and static ship information, such as MMSI, call sign, position, course and speed, to other AIS transponders and base stations
VHF range, 20-30 Miles , potentially can see around bends
Who is required to have AIS
Vessels required to have AIS
All vessels over 300GT on international voyages
All cargo vessels over 500GT not on international voyages
All passenger vessels
What are the 3 types of info transmitted by AIS
Static - Does not change, ships name, mmsi (Maritime Mobile Service Identity)
location of AIS antenna
Voyage - Port of origin/destination, status eg Anchored etc
Dynamic - Heading, SOG, COG, Position, Speed, RoT
Difference between class A and B AIS
A meets the requirements of Solas, B does not. So B may only be used on ships which are not required to carry AIS
When should AIS be on?
Should always be in operation when ships are underway or at Anchor
If the Master believes the vessels security is at risk, it may be switched off,
But this should be reported to the VTS if in one, and noted in the Logbook
How often should the Static data be checked?
Which dynamic data should be periodically checked?
Once per month or once per voyage, whichever is shorter
Positions given according to WGS 84
SOG
Sensor information
Limitations/ Hazards of AIS
1 Collision avoidance should be carried out in provision with the COLREGS, the colregs make no mention of AIS, only visual/radar
2 AIS relies on SOG/ ground stabilised, Colision avoidance is based on STW/aspect
3 Not all ships/valid targets are fitted with AIS
4 AIS is reliant on GPS, brings its own inaccuracies/ errors
5 Faulty inputs will lead to faulty outputs. The AIS will not detect this
6 Can be switched off
Types of ATON, differences between
Physical - real Bouy, with AIS mounted on it
Diamond shape on chart - Purple Circle on ECDIS
Synthetic - Real Bouy, overlayed AIS target from shore
Virtual - Nothing there, overlayed AIS target from shore
Open/hashed Diamond shape on chart
What is LRIT
When introduced
Applies to Who
How does it work
Long Range Identification and Tracking
Starting from 2009, Under SOLAS applies to;
All passenger ships
Cargo ships over 300GT
Transmits every 6 hours, via satelite
Contracting governments can track any ship within 1000NM of its coast
Ports, notified of vessels en route, can track such vessel
Connected to UPS
What is BNWAS?
Bridge Navigational Watch Alarm System
To check that the watchkeeper has not fallen asleep
3-12 Minute countdown, 15 secs visual, 15 secs audible alarm, if not reset, alerts master, then crew after 90 secs
3 modes, auto (on when autopilot is on) , Manual on, Manual Off
Which MGN gives info on LRIT
MGN 634
