Radial turn
1. Decide Radius R for the turn taking into consideration the factors of ship such as LOA,
displacement, Breadth, list, trim, shallow water effect, effectiveness of rudder, and other
external factors.
2. Draw a line AB and BC initial course line and final course line and angle between them is
alteration theta
3. On line AB and BC cut a distance of R tan theata/2 to get point P on AB and Q on BC
4. From point P and Q cut an arc of R such that they meet at point O
5. From point O draw circle such that it passes tangentially on points P and Q
Rate of turn ROT = Ship’s speed in knots / Radius of turn
While doing an alteration of 90 degree the ship’s speed is reduced by 25 % and thus rate of turn
reduced as the formula we can see if speed reduce the rate of turn also reduces
To maintain the radius 2 miles constant we need to maintain Rate of turn and speed of the ship
Uses and benefits of ROTI
- Transiting confined channels
- Conning a large vessel
- Elimination of XTE on the new course
- Can be plotted electronically on ARPA
- Can be plotted on reflection plotter
Doppler log
- It works on the principle of Doppler principle or Doppler shift
- Doppler shift say that the frequency received by observer is different that the frequency
transmitted by source as there is relative motion between source and observer
- Due to motion between source and observer, the change in frequency is called apparent
shift
- This change is frequency can be more and less
- Apparent frequency received by observer is more when observer and source one of them is
moving towards each other
- Apparent frequency received by an observer is less when observer and source one of them is
moving apart
Janus configuration
- The transducer normally transmit acoustic waves in 60 deg direction towards the seabed
- But due to pitching or change in trim this angle changes due to which error comes in speed
of ship
- To overcome this two transducer are fitted on keel of the ship
- One transducer transmit in forward direction
- Another transducer transmit in aft direction
- The difference of frequency received and transmitted gives relation of speed of ship
This arrangement of two transducer one transmitting in fwd direction another in aft direction to
overcome the error in speed is called Janus Configuration
EM log
- Electro magnetic log is a device used to determine ship’s speed
- It calculates ship’s speed with respect to water, which is speed through water
Principle
- This log works on the principle of Faraday’s Law of Electro magnetic induction
- When moving conductor cuts the stationary magnetic field
- Or moving magnetic field cuts a stationary conductor
- Then EMF (electro motive force) or current is induced in the conductor
This emf or induced current is directly proportional to the following
- The intensity or strength of magnetic field
- The length of the conductor passing through magnetic field
- Rate of change of magnetic field cutting the conductor
EM log
- It is instrument which is used to calculate ship’s speed
- It calculates ship’s speed with respect to the water, speed through water
Principle
- It works on principle of Faraday’s electro magnetic induction when a moving conductor
passes through a stationary magnetic field or stationary conductor cuts the moving magnetic
field then an EMF Electro Motive force is induced hence current induced in the conductor
- This EMF hence current is directly proportional to the following
- Length of the conductor passing through magnetic field
- Strength of the magnetic field
- The rate of change of magnetic field cutting the conductor which relates to the velocity of
the conductor
EMF = FLV
Where F = magnetic flux
L = length of conductor
V = velocity of the conductor
GPS
Space segment
- It consists of 24 satellite in the total 6 orbits around the sun.
- Each orbit consists 4 satellite
- At any time 6 satellite is visible at any place on earth.
- Each orbital plane is spaced apart by 60 deg
- Each satellite has its own propulsion system which can be remotely operated
- Each satellite remains above horizon for 5 hours and coverage of the satellite is 4500 nm
Space Segment
- It consists of 24 satellite and 6 orbital planes around the earth
- Each orbital plane consists of 4 satellite
- Each satellite are having its own propulsion system which can be remotely operated
- Each orbital plane is spaced apart by 60 deg
- Each satellite remains above horizon for 5 hours and coverage of 4500 nm
- At any given time 6 satellite are always available for transmission and reception
- The orbital period half of sidereal day 11 h 58 m so that each satellite is seen twice a day
Ground segment
- A master station
- An alternate master station
- 4 dedicated ground antenna station ( 2 in Atlantic, each in indian ocean and pacific ocean)
- 6 dedicated monitoring station ( 1 for each master station and 4 for ground antenna station)
User segment
- It consists of antenna, receiver built in computer with display unit
- It records and intercepts signals from satellite
- Initially locks down to a satellite then extract almanac then select 4 most suitable satellite
- Track these 4 satellite and obtain their ephemeris data
- Calculate the time taken to receive the signal from the satellite and hence calculate the
distance to each satellite.
- Calculates and display the fix
- Generally able to store programmed routes and waypoint etc.
Geodetic Datum
- Geodetic datum is a tool used to define the shape and size of the earth, and also used as a
reference point for the various coordinate system used in mapping the earth
- GPS error
1. Clock bias error
- The receiver clock is not as accurate as of the clock fitted on the GPS satellites. the time is
updated every subframe (6 sec). The range obtained for the fix will not be accurate and thus
these ranges are called Pseudo ranges.
- The accurate fix can be obtained when 3 satellite is used to determine the range
VDR
- Date, time, position
- Heading
- Depth
- Bridge and VHF audio
- Speed
- Status of hull opening
- Engine order
- Rudder order
- Bridge Mandatory Alarms
- Course
- Radar image
- ECDIS image
- AIS data
- Watertight and fire door status
- Wind speed and direction
- Rolling motion
S-VDR
- Date, time and position – GPS
- Speed
- Depth
- Heading
- Bridge and VHF audio
- Radar Display image
A master station
An alternate master
4 dedicated ground antenna station ( 2 in Atlantic, 1 each in indian and pacific)
6 dedicated monitoring station
Ground segment
- A master station
- An alternate master station
- 4 dedicated ground antenna station ( 2 for atlantic ocean , one each for indian ocean and
pacific)
- 6 dedicated monitoring station ( 2 each for master station, one each for dedicated ground
antenna station)
-
Echo sounder working
The oscillator generates high frequency electrical signal and send it to the transducer fitted on the
keel which converts it into that acoustic waves and transmit it to the seabed at rate of 600 acoustic
pules per min having the beam width of 12 to 25 degrees.
Now after reaching to the seabed these acoustic waves get reflected back in the form echoes
towards the ships hull and captured by the transducer and then it converts these echoes into
electrical signal which is relatively weak as compare to the transmitted signal
To increase the power of these signal, it goes to the Amplifier unit, which amplifies these signal and
then it sends to the recorder, where stylus, which burns the thin coating of aluminium powder and
black marking made on the paper and hence depth under the ship keel is recorded on the paper.
D = V x T/2 (D = Depth of the seabed, V = velocity of the waves in sea water 1500 m/s and T = time
taken by waves to reach back to the transducer)
Errors in Echo sounder
1. Propagation Error – speed of sound waves varies with change in temperature and density of
water
2. Stylus speed error – stylus speed is constant but due to some issue with power supply of
voltage fluctuation
3. Pythagoras error – when two transducers are used and spacing between them is more than
2 m. This error can be calculated by simple Pythagoras theorem
4. Aeration – due to rough weather and pitching of vessel air bubble are formed and they can
reflect the sound waves as false echoes
5. Multiple Echo error – this occur when single echoes reflect back and forth between hull and
seabed because of being a very strong echo
6. Cross Noise error - due to sensitity of the transducer the transmitted waves gets received
there only before reach the ground so it gets amplified and zero reading will be shown on
recorder
7. 2nd trace echoes
8. Thermal error
9. Zero Error / Draft Error
Aeration
Stylus speed error
Propagation error
Stylus speed error
Multiple echo error
Cross noise
2nd trace echo error
Pythagoras error
Zero/ adjustment error
Zero/ draft error
Thermal error
Expanding square search –
- Used when location of the search object is known
- Used when the search area is small
- Used when concentrated search is required
- Due to small area, this procedure must not be used by simultaneously multiple aircrafts or
multiple ships
- Datum must be known in the proximity
- The starting leg must always be in the windward direction from there 90 degree alteration
must be done with increasing distance according to search pattern
- As soon as you have made your first alteration in either stbd or port the rest of the alteration
must be in same direction as of your initial alteration
- CSP – commenced search point
-
Sector search
Used when
- Search area location is known accurately
- CSP is the point from where the vessel or aircraft start the search
- Every alteration 120 degree
- Must carried by individual vessel or aircraft
- This type of search pattern when the datum position is known in the vicinity
- This search is carried as keeping the datum as centre of the search pattern
AIS
- As per solas requirement,
- Every vessel of 300 GT and above which are on international voyage must be equipped with
operational AIS
- Every vessel of 500 GT and above which are on Coastal voyage must be equipped with
operational AIS
- All passenger vessel irrespective of size must be equipped with operational AIS.
-
-
- Automatic Identification System is an instrument which works on principle of line of sight
same as VHF and used very high frequency to transmit and receive data.
- Range of AIS is same as VHF around 20-25 nm.
- used as aid to navigation, it broadcast data of a ship among ships in vicinity.
- It gives data of ship such as name of ship, identification, position, course, speed, ETA etc.
- Ais system has one vhf transmitter and two vhf receiver which works on STDMA self
organised time division multiple access
- Channel 87 B – 161.975 MHz
- Channel 88 B – 162.025 MHz
- It uses STDMA in which 2250 slots are allocated every min for transmission of data, where it
takes 26.67 millisecond, where rate of transmission or reception is 9600 bits/second. The
maximum size of data that can be transmitted is 256 bits, so because of two channel 87 b
88b therefore the number of slots will be double that is 4500 slots.
-
Type of message or data
1. Static Data
- Name of Ship
- Call Sign
- IMO number
- Type of ship
- Dimension of ship (LOA, Breadth, Depth of ship)
- Port of registry
2. Dynamic Data
- Utc
- Position of ship
- Navigational status
- CMG and COG
- Heading
- ROT
- CPA & TCPA
This dynamic data is sent as per navigational status
When at anchor – every 3 min
When 0-14 kts – every 12 sec
When 14-23 kts – every 6 sec and 2 sec changing course
When more than 23 kts – every 2 sec
3. Voyage data
- Ship’s draft
- Type of cargo
- Person on board
- Next port of call
- Last port of call
- ETA
4. Safety related data
- This data is text message sent only when safety of life at sea, safety of environment and
safety of navigation
Every 6 min all data i.e. Static, Voyage and Safety related data transmit except dynamic data
LRIT
- Long Range Identification and Tracking system
- It works as identification, tracking and monitoring of the ships
- It works through satellite system which sends signal to land earth station received from the
ship via satellites
- It automatically sends data which are Identity of ship, position of ship with UTC time without
any human intervention in every maximum 6 hours interval.
LRIT system
1. Shipboard LRIT information transmitting equipment
2. CSP Communication Service Provider
3. ASP Application Service Provider
4. LRIT data centre
5. LRIT Data Distribution Plan
6. IDE International Data Exchange
BNWAS
Requirement
- Ships which are 150 GT or above shall be equipped with BNWAS
- Passenger ships irrespective of size shall be equipped with BNWAS
- Bridge Navigational Watch Alarm System
- It is an equipment which is designed to monitor bridge activity and operator disability which
can lead to marine accidents
- It alerts the OOW in a fixed interval min 3 and max 12 of time to keep safe a bridge
watch.
- It is an essential equipment on bridge in active manning of bridge therefore the
equipment is password and key or password is only with the master
Modes of BNWAS
1. Auto – when auto pilot is engaged then BNWAS is in operation automatically and if hand
steering is engaged then BNWAS is not in operation or off.
2. Manual OFF – in this BNWAS is always in operational
3. Manual ON – in this BNWAS is completely OFF.
Procedure of BNWAS
- As per SOLAS requirement, the minimum time interval at which it should give alarm is 3 min
and maximum time interval is 12 min.
- There are three stages of alarm
- Stage 1 = At this stage, alarm is only visible, this visible alarm will go on for 15 sec, if the
OOW is not able to acknowledge this alarm then it will give both audible and visual alarm for
next 15 sec.
- Stage 2 – If stage 1 alarm is not acknowledged within the 30 sec, then alarm will
automatically move on to stage 2.
- This stage is prohibited for all passenger ships and optional for cargo ships.
- This stage alarm then triggered on to the backup officer cabin and a visual and audible alarm
will be sounded then backup officer have around 90 - 180 second to acknowledge the alarm
- This alarm is always be acknowledged from the bridge
- If not acknowledged within 90 -180 sec then it goes to next stage.
- Stage 3 – In this stage, a visual and audible alarm is activated in master’s cabin and
throughout the ship
VTS
- It is a vessel traffic service which is used by shore people to offer assistance to ship
navigation in congested water
- It monitors the vessel movement and regulates traffic
- It ensures that all vessel follows appropriate traffic lanes and do not end up in close quarter
situation or collision
- It enhances safety of navigation
- It also ensures that no vessel is doing any smuggling or malpractice by close monitoring
- It also suggests vessel best route to manoeuvre in confined waters
Surveilled – in this monitoring of vessel is done remotely by adopting modern methods
- In this sensors are used to monitor the traffic of vessel
- These sensors are land based like RADAR, AIS and CCTV which give important marine
information.
Non-Surveilled –
- In this vessel has to report to the VTS operator their information regarding ship
- The vessel report to the VTS operator about their Identity, Last port of call, Draft, Next port
of call, type of cargo carried, no of crew onboard
- By using these information VTS regulates and manages the traffic movement
-
Ship reporting system elements
- To provide up to date information related to search and rescue
- For effective vessel traffic management service
- For weather monitoring and forecasting
- For prevention of pollution of marine environment
Types report sent by vessels
- Sailing plan
- Position report
- Deviation report
- Final report
- Dangerous goods report
- Marine Pollutant report
- Any other report
Sailing plan
Position report
Deviation report
Final report
Dangerous goods report
Marine pollutant report
Other report
Squat –
- Due to motion of ship, the bow displaces water and when water fills up this place then high
pressure is formed in fwd and low pressure in aft due to which streamline flow of water
occurs from fwd to aft and causes a vertical sinkage of ship
- And this Overall reduction of under keel clearance is called squat
The factor which affect the squat are
- Speed of vessel
- Block coefficient
Squat directly proportional to the block coefficient
And square to the speed of the vessel
- Depth of water
- Blockage factor
- Passing another ship in a river or canal
Pivot point
- It is the point about which ship turns in any rudder order is given.
- It is the point about which the vessel is assumed to swing when taking a turn by giving a
rudder order.
- The position of pivot point is not fixed and it depend upon the following factors
- When ship is moving forward
- When ship is moving astern
- When ship is stopped
- When ship is trimmed by head or stern
- When ship is stopped
It lies on COG
- When ship is at anchor
It lies on the outer edge of hawse pipe
- When ship moving ahead but at constant speed
The pivot point lies ¼ of the distance from fwd
- When ship is moving ahead with accelerating speed
The pivot point lies 1/8 of the distance from fwd
- When ship is trimmed by head or stern
It lies to the part of the ship where the ship is more submerged in case of trim by head it is
on fwd and in case of trim stern it lies in aft part
Transverse thrust
- It is the movement of stern in port or stbd direction due to the movement of propeller in
right handed propeller.
- when moving astern or ahead, prominently when moving astern
- When moving astern, the propeller rotates, in stbd side the water is pushed in upward
direction, displacing the water towards stbd side, and in port side of propeller the water
pushed downward where water also displaced in the stbd direction
- Thus causing the ship’s stern to move in port side and bow in stbd side
- When ship goes in astern then it can be seen the vessel swings in stbd side in forward part
and port side in stern side.
- This movement of stern in transverse direction port or stbd direction is called transverse
thrust
- This effect also happens in case of ship move ahead but due to vessel move away from
propeller wash this effect is very less.
Bow cushion effect
- In shallow water narrow channel, bank, canal, river, when ship approach towards a bank, the
bow pushes away from the bank, this called Bow cushion effect.
- In forward part positive pressure formed which cause the bow to move away from the bank
Bank cushion effect
- In shallow water, narrow channel, bank, canal, river when ship approaches towards a bank,
the stern part of vessel get attracted and move towards the bank, this effect called bank
suction effect.
- the low pressure is formed at the stern part of the vessel which cause the stern to move
towards the bank
Wheelhouse poster
1. General particular
- Name of ship
- Call sign
- IMO number
- Draft at which trials conducted
- LOA
- LBP
- Moulded Breadth
- Moulded Depth
- Extreme Breadth
- Extreme Depth
- Deadweight,
- Load Displacement
- Lightweight displacement
- Service speed
- Parallel body of the ship
2. Propulsion and manoeuvring equipment
- Main engine particular
- Main engine power
- RPM
- Speed at loaded and ballast
- Speed at Full/Half/Slow/D. Slow at Ahead and Astern
- Critical RPM
- Crash stern
- Rudder type
- Time for hard over to hard
- Bow thruster
- Propeller type
- Number of propeller
- CPP and Right or left handed propeller
- Turning circle test in loaded and ballast in shallow/deep water
- Emergency stopping manoeuvre at full sea speed and full astern speed
- Estimated squat in deep, shallow water, unrestricted and confined water
Pilot card 1st and 2nd same
But last one other navigational equipment
- RADAR
- ARPA
- ECDIS
- ROT Indicator
- AIS
- VDR
- VHF
- ECHO Sounder
- Gyro
- Speed log
- Anchor
- Whistle
- Signal Light
Any deficiencies regarding manoeuvring or special requirement
Turning Circle
1. Advance
It is the perpendicular distance travelled between Execution (start) Point and to the point
where the heading is changed by 90 degrees from the initial heading.
2. Transfer
It is the perpendicular distance from the original course line to the point where the heading
is changed by 90 degrees from the original heading.
3. Tactical diameter
It is the perpendicular distance from the original course line to the point where the heading
is changed by 180 degrees from the original heading.
4. Turning radius
It is the radius of the turning circle made when ship has swung by 180 degree from initial
heading.
5. Final diameter
The diameter of the turning circle when ship has swung by 180 degree from its original
heading
6. Drift angle
- It is the angle made between the ship heading and ship cog ( tangent to the path).
- Drift angle is larger then turning circle will less and ship will turn faster
- If drift angle is smaller then turning circle will be large and ship will take more time to turn.
Contents of BPG
1. Bridge Organisation
2. Passage Planning
3. Duties of the officer of the watch
4. Operation and maintenance of bridge equipment
5. Pilotage
Annexes
1. Dynamic Positioning
2. ECDIS Carriage Requirement
3. Checklist
a. Pilotage
b. Bridge
c. Emergencies
1. Bridge Organisation
2. Passage planning
3. Duties of the officer of the watch
4. Maintenance and operation of the bridge equipment
5. Pilotage
Annexes
- Dynamic positioning
- ECDIS carriage requirement
- Checlists
Pilotage
Emergencies
Bridge
Dynamic positioning
ECDIS carriage requirement
Checklist
Pilotage
Bridge
Emergencies
Annexes
1. Dynamic Positioning
2. ECIDS Carriage requirement
3. Checklist
- Pilotage
- Bridge
- Emergencies
Annexes
1. Dynamic positioning
2. Ecdis carriage requirement
3. Checklists
- Pilotage
- Bridge
- Emergencies
Bridge organisation
Passage planing
Duties of the officer of the watch
Operation and maintenance of bridge equipment
Pilotage
Bridge Organisation
Passage Planning
Duties of OOW
Operation and Maintenance of Bridge equipment
Pilotage
annexes
