Function 1-Navigetion Oral Notes Page|1

FUNCTION 1
NAUTICAL PUBLICATIONS
WHAT ALLPUBLICATIONS ARE REQUIRED BY AVESSEL TO CARRY ONBOARD?
The Camege of Nautical Publication listis found in Annual Summary of admiralty notices to
mariner

UST OF OFFICIAL PUBLICATIONS

International code of signals
The Mariner Hand Book
MSN, MGN, MIN (M NOTICES)
NTM (NOTICES TO MARINERS)
ALRS
ALLFS
Sailing Directions
Nautical Almanac
Navigation Tables
Admiralty Tide Table
Tidal Stream Atlases
Operation and Maintenance Instructions for navigational aids carried.

1) ADMIRALITYUST OF NOTICES TO MARINERS (NTMS)

U
a)Weekly notices to mariners
b) Annual notices to mariners

c)Cumulative notices to mariners

a)WEEKLYNOTICES TO MARINERS
I t contains information that enables the
mariner to keep his charts and publications
to date with latest reports. up

Total weekly notices to mariners in a

year: 52
They should be retained onboard until the next
MARINERSis received. ANNUAL SUMMARY TO NOTICES TO

Pulkit Nande
Function 1-NavigationOral Notes Page 12

However weekly editions dating as far back as 18 MONTHS may be required to be kept
onboard.

Weekly notices to mariners are divided into 8sections:

Section-
Explenatory notes &Index to use ofcharts & otherpublications
Section l -Admiralty NTM, Corrections to charts
Section lHiM- Reprints to radio navigational wamings
Section V-Corrections toASD
Section V- Corections to ALLFS

Section V- Corrections to ALRS

Section V-Updates to miscellaneous nautical publications

Section vl-Updates to digital publicetions

b)ANNUALNOTICES TOMARINERS-NE 247(1)&NP247/2)

I t is published annualy
I t contains all the corrections for the particular year.

Contents of NP 247(1:
1. Sectiont - contains important topics which are likely to remain valid for some time (ex.
List of TSS)

2 Section 2- temporary &preliminary notices

Contents of NP 247(2
1. Section 1 list of current editions ofallASD with their supplements
2 Section 2- amendments to ASD which have been published in Sec IV of weekiy NTM

of time but will not be initiated

Temporary notlce; Information valid for a limited period3-6
permanently if the duration of validity is less, between months.

Preliminary notice; Early promulgation to mariner about some work and action/work shortly
will
be taking place example: harbour developments

Nav.Waming: Early information of important incident which may constitute to be a danger to

navigation.

Pulkit Nande
Function 1-Navigation OralNotes Page 13

)CUMULATIVE NOTICESTO MARINERS-NP234/A)&NP234B)

Published twice in an year JANUARY &JULY
I t contains information affecting various charts

January &July both edition contains information of last 2 vears (weekly NTM's)
Contents of both parts are the same

INDIAN)
a) Fort Nightly edition
b) Annual edition

c) Special edition

a)FORTNIGHTLY EDITION
Published every fortnightly (15 days) i.e. 01" and 15h of every month.
Published by NAVAL HYDROGRAPHICOFFICE DEHRADUN
Itis divided into
10Section
Section-- Index of charts affected

Section ll- Permanent notices

Section IHm- Temporary& Preliminary notices
Section V- Marine Information
Section V- Reprint of radio nav. Wamings
Section VI- Corrections to ASD

Section VIl -

Corections to ALLFS
Section VIl- Corrections to ALRS
Section IX -Use of GPS for navigation using local datum charts
Section X- Reporting of nav. Danger

b)ANNUAL EDITION
Function 1-Navigation Oral Notes Pagel4

Same as UKHO
Published every year

cSPECIALEDITION
Itis published at an interval of 4YEARS
The information published contains
a) Temporary &preliminary notices annual summary
b) Amendments to ASD- annualsummary

c)Amendments to ALRS-publishedquartery
d) NAVAREA, Hydroplant messages weektredition

HYDROGRAPHIC NOTE
Hydrographic note allows the mariner to infom the UKHO about any navigationally
significant information. This information could include new or suspected dangers,
changes to navigational aids, amendments to details included in publications and
suspected charts and publications that could be counterfeit.

1)H102:trdroaraphienatefor Generalinfomnaton
2)H102 A:rographicnote for Portinfometion
3) H102:Hrdrographicnotefor CPS/Chartdetumobservetions
2)CHARTCATALOGUE(NP 131)
I t has 39 sections and 10 parts
Revised andre-published on 01 DECEMBER ofevery year(Indian chart catalogue
published on 01 JANUARY of every year)

I t gives information like:

a) Date of publication

b) Title of chart

c)BAchart number
d)Date of new edition

e) Natural scale for all charts

9 Diagrammatic representation of limits of navigational charts

Pulkit Nanda
Function 1-Navigation Oral Notes Pagel5

cORRECTION OF CHART CATALOGUE:

WEEKLY NTM-SECTION

3)PAPER CHART MAINTENANCE RECORD (NP 133A)

Contains list of all paper charts onboard

Corrections to paper charts are mentioned in this record

4)ADMIRALTY SAILING DIRECTIONS (ASD) (NP 1-NP 75)

I t ' s another is
name
"PILOT BOOK
Applicable to ships 2150 GRT
Itis essential for PASSAGE PLANNING
Covers various navigable areas of the world

TOTAL vOLUMES: Z5
ASD gives the following information to the mariners:
a) Local regulations

b) Climate conditions

c) Navigational hazards
d) Port facilities

e) Harbour approaches

Buoyage system
9Weathercondition
New volume published every 12 YEARS
Kept updated by supplement every: 18 MONITHS
F o r INDIA: BAY OF BENGAL PILOT- NP 21

INDIAN WEST COAST PILOT NP 38

cORRECTION TO ASD:
WEEKLYNTM-SECTIONIV, ANNUAL NTM-NP247(2)
Function 1-Navigation Oral Notes Pagel6

5)OCEAN PASSAGES OFTHE WORLD

Published by HYDROGRAPHIC OFFICE OF NAVY

Contains notes on meteorological factors affecting the passage

I t guides the mariners to follow the best passage in a particular month through a
particular track.

I t also provides information such as wind, sea, curent, Ice, and load line rules.
I t is divided into 4 PARTS

a) Part1-powerdriven vessels (chapter 1-8)

b) Part 2- sailing vessels (chapter 9-11)

c) Part 3-a comprehensive

generalindex
d) Part 4-cherts anddiagrems
CORRECTION TO OCEAN PASSAGES OF THE WORLD: WEEKLYNTM- SECTION VI

6) GUIDE TO PORT ENTTRY

I t is published in 2 volumes (AK)&L2
I t covers the ports of entire world and gives information regarding port and harbor
approaches to various other parties concerned with shipping like masters, charterers,
agents, etc.

It has 2 parts:
PART 1- Information about Ports & its approaches

PART 2- List plan of Important ports

7) ADMIRALTY LIST OF LIGHT &FOG sIGNALS (ALLFS) (NP 74-NP87)

I t has total 14 volumes (4HJN&P
Volumel&0 are omitted

V o l u m e Fis for INDIA - NP 79

I t covers all the world geographically

Function 1-Navigstion Oral Note Page17
Published every 12 MONTHS
I t gives information about the lights with following characteristics:

a) Location name

b) Lat&Long
c)Characteristics (ex: f1Y 4sec)
d) Elevation

e) Range
Height
9) Remarks

h) Luminous range diagram

cORRECTION TO ALLFS: WEEKLY NTM-SECTIONY

8) ADMIRALTY LIST OFRADIO SIGNALS (ALRS)(NP 281-NP 286)

I t has total 6 volumes
A l l volumes published: ANNUALLY(except VoL4or NP 284)
Volume 4 published: 18 MONTHS
a)NP 281-Coast Radio Stations
b) NP282-Radio NavigationalAids
e)NP283- Maritime SafetyInformation Services
d)NP284-Meteorological Observation Stations
e) NP 285 GMDSS

NP 286-Pilot Services, Vessel Trafic Services & Port Operations

cORRECTION TO ALRS: WEEKLY NTM-SECTIONV

9)TIDAL STREAM ATLASS

Tidal stream atlas (TSA) gives the tidal prediction for every hour including RATE&
Function 1 Navigation Oral Notes age 18

f the springs and neap of each 6 hrs before and after high water for the
DIRECTION
particular place.
I t has no
COMPASS ROSE
Measures by PARALLELRULER FLOOD TIDE EBB TIDE

Direction oftidal streamis indicated byan arow

TIDAL DIAMOND indicates the geographical position. TIDAL DIAMOND

10)CHART SYMBOL &ABBREVIATIONS

CHART 5011(UK - Itis a nautical publication published by British Admiralty that covers

an entire range of symbols and abbreviations used in BA charts.

CHART 5020(INDIAN) - It is alsoa nautical publication published by NAVAL

DEHRADUN that contains symbols used in charts

HYDROGRAPHIC DEPARTMENT,
published by the naval hydrographic office.

11)ADMIRALTY TIDE TABLES(NP 201-NP208)

I t details the time & height of high and low waters for various standard and secondary
ports of the world.

I t is published ANNUALLY,

Total volumes:
8volumes
1) NP 201- UK & Ireland

2) NP 202- Europe, Mediterranean Sea &Atlantic ocean

3) NP 203- Indian ocean
4) NP 204-South Pacific ocean
5) NP 205-South China sea &Indonesia
6 NP 206-North Pacific ocean
7) NP 207-South West Atlantic ocean &South America
8) NP 208-South East Atlantic ocean, West Africa &Mediterranean
I t has 3 parts:

Pulkit Nanda
Function 1-Navigation Oral Notes Page 19

Part 1- predictions of time & height of high & low waters at standard ports
Part 2-predictions for secondary ports
Part 3 list of principal harmonic constants
coTTECTION TO ATT:
ANNUAL NTM

12)MARINERS HANDBOOK(NP 100)

I t i s a comprehensive guide to seamanship and gives information about navigation to
mariners.

I t gives information about charts, nav. Infomation, supply ofcharts,nav. Waminge

buoyagesystem, light & fog signals, lceberge, meteorology, observation &reporting of
hydro infommation, etc.

13)ADMIRALTY DISTANCE TABLES(NP 350)

The tables give shortest navigable distance between important positions & chief ports of
the world without considering the effect of current and weather.

I t is published in 3VOLUMES
1) Vol 1 (NP 350-1) - Atlantic ocean, Mediterranean sea, Canibbean sea, W Europe

&Gulf of Mexico
2) Vol 2 (NP 350-2) - Indian ocean, Red Sea, Persian Gulf, Easten Archipelago, 2

parts of Southern Ocean from South Africe to New Zealand

3) Vol3 (NP 350-3)- Pacific ocean & its sea boundary

14) ROUTEING CHARTS

These charts are also called PILOT CHARTS
Very useful for planning of ocean voyages Publishedfor each.month ofthe year
These charts give prominent sea routes & distance between major ports for a particular
month.
nformationregarding-prevalingcurents,atmospherlc pressure via isobars, alr
& sea temperature, ioed ine zones, ice limits, annual variation, etc

Pulkit Nanda
 Page l 10
Function 1-Navigation Oral Notes
Total chartspublished8x12-96charte
&REGIONS ARE
1) North Atlantic

2) South Atlantic

3) North Pacifc

4) South Pacific

5) Indian Ocean

6) Malacce Strait to Marshallslends

7) Caribbean Sea & Gulf of Mexico

&)Mediterranean & Black sea

15) NAUTICAL ALMANAC

I t contains all the data required for the practice of Astronomical navigation at sea
Data for the whole year is provided in the almanac

Published - ANNUALLY

16)STARFINDER AND IDENTIFIER (NP 323)

Consists of diagrams, on which are plotted, the 57 stars listed on the pages of Nautical
Almanac.

17)M-NOTICES& MS NOTICES
These notices contain essential information for the safety of ships & seaman

These notices can get suppressed, cancelled or new pages inserted

These notices are issued for the safety of navigation and accidents which have occurred
earlier.

a) MNOTICES
M notices are the notioes that are
printedbytheUK MARINEDEPARTMENT on
Function 1- Navigation Oral Notes Page 111

accidents that had occurred earlier, their causes and recommendations for
prevention.
These notices are issued as:

1) MARINESHIPPING NOTICES(MSN) These contain mandatory

information that must be complied with respect to the legislation they
refer to.

2) MARINEGUIDANCE NOTICE MGN) These give information about

guidance to mariners about safety of shipping and of life at sea and to
prevent or minimize pollution from shipping.

3) MARINEINFORMATION NOTICE(MIN) These give information that is

valid for a short duration of time and is relevant for a smalil group of
people.

b)MS NOTICES
MS notices are lssued by GOVT.OF INDIA(DGSHIPING) on occured accident causes
and recommendations on prevention.

18) INTERNATIONAL AERONAUTICAL AND MARITIMESEARCH AND

RESCUE MANUAL(IAMSAR MANUAL)
Published byIMO & ICAO (nternational Clvil Aviation Organization)
t i s a combined search &rescue system by civil aviation & marine organizations to
provide assistance to people in distress while travelling by sea & air

I t has 3Volumes

1. Vol
1-Organisetion&Managemen
2 Vol2-Mission Co-ordination

3. Vol3-Moble Facilites(Compulsorytobecaried onboard)

Volume 3is dvided Into4Sectlong
1) Sec 1-Overview

2) Sec2-Rendering Assistance
3) Sec 3-Onscene co-ordination
4) Sec 4-Onboard Enmergencies
Function 1-Navigation Oral Notes Page 112
Various Search patterns in IAMSAR are:

1)BXPANDING SOUARESEARCH
Most effective when the location of the search objet is known within relatively close
limits

Commence position is always DATUM position

Appropriate for vessels or smal boats to use when searching for distressed person or
object with little or no leeway

Due to small area involved, this must not be used by multiple aircrafts or vessels

Accurate navigation is required, first leg is oriented directly INTO THE WIND to minimize
error

Difficult for fixed-wing aircraft to fly legs close to datum if S is less than 2NM.

2
st DATUM2S 4S 6S

Expanding square search (SS)

2) SECTOR SEARCH
Most effective when the position of search object is known, search area is small.

Used to search a circular area centered on a datum point.

Due to small area involved, this must not be used by multiple aircrafts or vessels.

A n aircraft & a vessel may not be used together for independent sector searches
Asuitable marker like a smoke float or radio beacon may be dropped at datum position
and used as reference for centre.

For aircraft, search pattern radius is between 5NM & 20NM.

Function 1-NaviaetionOral Notes Pagel13
For vessels, search pattern radius is between 2NM & SNM, each turn is 120 degrees,
normally turned to starboard.

n Cc Viy

dLEG
DATUM

1s LEG

rd Crossleg
LEG

d LEG

ndLEG\
Search

Second Search

Sector pattern: single-unit (VS)

3) TRACKLINE SEARCH
Nomally used when an aircraft or vessel has disappeared without a trace along a known
route

Often used as initial search effort due o ease of planning & implementation

Search may be along one side of the track line & retum in opposite direction on the other
side

Aircraft are frequently used due to their high speed

Aircraft search height: 300m 600m during day, 600m 900m during night

1/2 S
TRACK OFMISSING
AIRCRAFT
1/2 S

Treck line search, return (TSR)

 Page l 14
Function 1-Nevigation OralNotes

TRACK OF MISSING AIRCRAFT

Track line search, nonreturn (TSN)

4 PARALLEL TRACK SEARCH

Used to search a large area when survivor location is uncertain

Most effective on water surface or flat terain

individual
Usually used when large area is to be divided into sub areas for assignment
to

search facility

Search legs are parallel to each other & to the long sides of the sub area
Can be used by multiple vessels

Trech
PATTERN2 PATTERN 3
Parallel track search -3 ships
Parallel track search 2 ships
Function 1- Navigetion Oral Notes Page l15

PATTERN4
Parallel track search-4 ship

PAT1ERN5
elpackngarch5ormoros

cONTOUR SEARCH
Used around mountains &valleys where sharp change in elevation make other patterns
not practical

Search is started from the highest point & goes top to bottom

Search altitudeintervals: 150m-300m

If the mountain cannot be circled, successive sweeps are made

Pulkit Nanda
Function 1-Nevigation OralNotes Page l16

Contour search (OS)

6)Co-ORDINATED VESSELAIRCRAFTSEARCH/CREEPING LINESEARC

Normally used when an on scene coordinator is present to give directions & provide
communications with the participating craft

The aircra most of the searching, while the ship steams along a course at a
speed directed by the on scene coordinator so that aircraft can use it as a
checkpoint
Gives a higher probability of detection
Ship speed varies according to the speed of the aircraft & size of the paten

UUU Creeping line search, co-ordinated (CSC)

Dullit
Function 1-NavigationOreal Notes Page 117

WILLIAMSON TURN
Rudder hard over (in an Timmediate action' situation, only to the side of casualty)
After deviation from the original course by 60", rudder hard over to the opposite side
When heading is 20" short of the opposite course, rudder to midship position and ship to
be turned to opposite course.

Williamson Turn:
1) Makes good original track line
2) Good in reduced visibility

3) Simple
4) Takes the vessel farther away from spot of incident

5) Slow procedure

ANDERSON TURN (ONE/SINGLE TURN

Single tun (270" manoeuvre)
Rudder hard over (in an "immediate action' situation, only to the side of casualty)

After deviation from the initial course by 250", rudder to midship position and stopping
manoeuvre to be initiated.

Anderson Tum:

Pulkit Nanda
Function 1- Navigation OralNotes Pagel18

1) Fastest recovery method

2) Good for vessels with tight turning characteristics

3) Used most by vessels with considerable power

4) Very difficult for a single screw vessel

5) Difficult because approach to person is not straight

250

SCHARNOV TURN
(Not to be used in an inmmediate action" situation)

Rudder hard over

After deviation from the original course by 240, rudder hard over to opposite side

When heading 20short of opposite course, rudder to midship position so that ship will
tun to opposite course

Scharnov turn:
1) Will take vessel back into her wake
2) Less distance is covered, saving time

3) Cannot be carried out effectively unless the time elapsed between occurrence of
incident and commencement of manoeuvre is known.

Pulkit Nanda
Function 1-Navigation Oral Notes Pagel19

240

20

19)MERCHANTSHIPSEARCH AND RESCUE MANUAL (MERSAR)

This manual was replaced by IAMSAR manual.
I t was published by IMO0
I t was so designed to aid the master of any vessel who was called upon to conduct SAR
operation

Contents of MERSAR:
Chap 1 Co-ordination of search & rescue operation

Chap 2 Action by a ship in distress

Chap 3 Action by assisting ships

Chap 4 Action by SAR aircraft

Chap 5 Planning &conducting the search

Chap 6 Conclusion of search

Chap 7 Communications

Chap 8 Aircraft casualties at sea

Annex 1 Standard format for search&rescue situation report (SITREP)

Annex 2 Man overboard manoeuvres

Annex 3 Requlation V/10 of SOLAS 74

Difference between1AMSAR&MERSAR
 Page 120
Function 1-Navigation Oral Notes
)IAMSAR is published by IMO & ICAO whereas MERSAR was published by IMO
b) IAMSAR contains added search patterns wherein compared to MERSAR which had
limited search patterns

c)IAMSAR has 3 volumes whereas, MERSAR had only 1 volume

INSPIRES(ndian Ship Positioning&InformationReporting System

4 types of messages are required:
1) SALING PLAN few hours before &after departure
2) POSITION REPORTING within 24 hrs before departure
3) DEVATION REPORT if any change in saliling plan

4) EINALREPORT immediately prior reaching destination

AMVERAutomated MutualAssistanceVesselReportingSystem)
Itis a wordwide reporting system managed bythe US
coast guard
Any vessel of 1000 GT &above or any vessel with voyage of 24 hrs or more can
participate in AMVER.

1) SAILING PLAN 5 days or a week before sailing

2) DEPARTUREREPORT as soon as possible
3) POSITION REPORT within 24 &48 hrs
4) ARRIVAL REPORT just prior to arrival port

5) DEVIATION REPORT if any change in sailing plan

IMOSAR(IMO Search &Rescue Manua

It gives guidelines to the government in implementing objectives of International
Convention of Maritime SAR 1979

2 parts are

1) Part 1- deals with the organisation of existing services

2) Part 2- contains infomation to assist all personnel

20) BRIDGE PROCEDURE GUIDELINES(BPG)

Function 1-Navigation Oral Notes Page l21

This is the book that provides guidelines, various checklists for safe navigation and
checklists used in cases of emergencies

Published by:INTERNATIONAL CHAMBER OF SHIPPING

It has 3 sections
Part A-Guldance for Mastere&WetchkeepinaOffcers
1) Bridge organisation
2) Passage Planning
3) Duties of Officer on watch

4) Operation &maintenance of bridge equipments

Annex 1 Pilot card

Annex 2 Wheelhouse poster

Annex 3 Guidance on steering gear test routine

Annex 4 Notice on the correct use of VHF channels

Annex 5 Required boarding arrangements for pilot

Part B-Bridae Checklste

1) Familiarisation with bridge equipment

2) Daily tests & checks

3) Preparation for sea

4) Embarkation/ Disembarkation of pilot

5) Master/ pilot information exchange

6) Navigation Deep sea

7) Navigation Coastal waters / traffic separation schemes

8) Changing over the watch

9) Preparation for arrival in port

10) Anchoring and anchor watch

11) Restricted visibility

12) Navigating in heavy weather or tropical storm areas

Pulkit Nanda
Function 1- Navigation OralNotes P age 122

13) Navigating in ice

PartC-EmeraencyChecklsts
1) Main engine failure

2) Steering failure

3) Gyro failure / Compass failure

4) Bridge control/Telegraph failure

5) Imminent collision /Collision

6) Stranding
7) Fire

8) Flooding
9) Boat / liferaft stations

10) Man overboard

11) Search & Rescue

BRIDGE EQUIPMENTS
1)BRIDGENAVIGATIONAL WATCH ALARM SYSTEM (BNWAS)
Vessel more than 150GT should have BNWAS latest by July 2014.

The purpose of BNWAS is to monitor bridge activity &detect operatordisability which

could lead to marine accidents.

System monitors the awareness of the 00W& automatically alerts the master or
another qualified 0OW if for any reason the 0OW becomes incapable of performing the
duties
OPERATIONAL SEQUENCEOFINDICATIONS&ALARMS
1) Once operational, the alarm should remain DORMANT for period between 3-12 seconds

Pulkit Nanda
Function 1-Nevigetilon Oral Notes Page 123
2) At the end of this period, the system should initiate a VISUAL INDICATION on bridge

3) If not reset, the system should sound an audible alam on the bridge 15 sec after the
visual indication is indicated.

4) If not reset, the system should sound a second audible alarm in the back up OOW's
location or master's location 15 sec after the first audible alarm is initiated on the bridge.

5) If still not reset then it should sound an alarm at location of further crew members
capable of taking action 90 sec after the second audible alarm.

2)GYROCOMPASS
I t has an electrically driven GYROSCOPE.

A heavy well balanced wheel spinning at more than 20,000 rpm.

It does not depend on EARTH'S MAGNETISM.

Itis free from variation&deviation of magneticeffect.
I t has freedom of movement on 3 axes:

1) SPIN AXIs

2) HORIZONTAL AXIS
3) VERTICAL AXIS

PRINCIPLE
Itwillworks on the principle of GYROSCOPIC INERTIA wherein afreely suspended magnet
point towards N - S direction cotinuously unless acted upon by an external force.

ERRORS

1) SPEED ERROR When the vessel is moving, the speed &course affects the gyro

Error maximum: N-S direction

Error minimum: E - W direction

I n northerly course error is WEST and in southerly course error is EAST.

Pulkit Nende
Function 1-Navigation Oral Notes Page 124

2) LATITUDE ERROR Also known as DAMPING error. (Damping is the tilt in the SPIN axis)
Error is proportional to tangent of latitude i.e. it increases with latitude

Higher the latitude, smaller the Earth's rotational speed

3)EIRSTROLLINGERROR
4) INTERCARDINAL ROLLINGERROR
5) BALLISTIC DEFLECTION
6) BALLISTICTILI
AQVANTAGES
1) It always shows TRUE NORTH
2) It has number of repeaters

3) The input can be fed to RADAR/ARPA/AUTOPILOT etc.

4) Does not use earth's magnetic field as reference

DISADVANTAGES
1) Itis electronic equipment. If power is hindered, the gyro stops
2) If the axle is out by several degrees then it might take some time to setle down.

PRECESSION
the angular displacement
tis ofthe spin axis when a torque is applied to the gyroscope. When
this torque is applied the resulting movement will be in a direction at right angle to the torque
applied
TILT
It is the angle of elevation or depression of the spin axis above or below the horizontal.

Rate oftiting=15/deg)xSin AzimuthxCos Lat=perminuteoftime

DRIFT
It is the movement of spin axis in the direction of azimuth.

Rate ofdrift 15(deg)xSinLat=perminute oftime

A t the equator, only tilt & no drift

Pulkit Nanda
Function 1-Navigation Oral Notes Page 125
A t the pole, only drift & no tilt

HOW TO MAKE GYRO NORTH SEEKING?

T h e requirement of gyro is that it must settle down and maintain a fixed direction with
respect to earth. This setling position should be such as that if the gyro is disturbed, it
must return back to the direction. To have this we must control the gyro and make it
north seeking.

I n general, it is done by creatinga torque about the horizontal East-West axis, which
produces a precession in Azimuth, and causes the spin axis to seek the meridian.

The control weight (Top/Bottom Heavy Effect) causes the spin axis to precess north
end to westwards when that end is tilted above the horizontal and north end to eastward
when tilted below the horizontal.

What heppens to Groiftisbrought to thepoles?

a) If the gyro is placed at the poles with its axis pointing eastwards, it will experience only
drift and not tilt.

b) Ifit is placed on the poles with axis pointing northerly, there will be no tilt or drift with the
rotation of the earth, but it will exhibit tum able effect (WANDERING) with its axis
pointing towards the celestial pole.

Why does Gyrofl athigheraltitude?

a)This is due to speed and dampina/lat eror
b) When ship travels in a northerly course the gyro settles to tit in west and for southerly
course towards east.

c)In an easterly or westerly course the error is added or subtracted.

3) MAGNETICCOMPASS
I t i s the primary means of direction indication of the vessel

I t i s the ships' STANDARD COMPASS

Itis fitted above the bridge on the monkey island at the centre line of the ship.

TYPESOFMAGNETIC COMPASS
DRYCARD cOMPASS
1) Made of rice paper