introtonavigationweb-110119151222-phpapp02

7/30/2019 introtonavigationweb-110119151222-phpapp02

http://slidepdf.com/reader/full/introtonavigationweb-110119151222-phpapp02 1/269

CHAPTER 1INTRODUCTION TO NAVIGATION



• Locate their position

• Travel from one place to another

Navigation enables mariners to:



Terrestrial Sphere or Globe

A sphere on which is depicted a map

of the Earth (terrestrial globe)



North Pole

South Pole

The north and south poles are

located at the ends of the axis on

which Earth rotates.



Meridians

Lines running through the poles and

around the Earth are called meridians.

North Pole

South Pole



The great circle of the Earth that isequidistant from the North Pole and

South Pole

(Cuts every meridian in half)

Equator



EQUATOR

60°

30°

0° 0°

60°

30°

60°

30°

60°

30°Northern Hemisphere

Southern Hemisphere



South Pole

North Pole

Eastern

Hemisphere

WesternHemisphere

South Pole

North Pole

NorthernHemisphere

SouthernHemisphere



Half of a globe

Hemisphere



Meridians and the equator are called

great circles because they divide the

globe into two halves.

EQUATOR

S pole

N pole

LONGITUDE

W E

GreenwichEngland



Any circle formed by the intersectionof a plane passing through the Earth’s

center, with the Earth’s surface

Great Circle



The equator is the only great circlegoing around the globe from east to

west. The other lines are called parallels,

since they go around the globe parallel

to, and north and south of the equator.

Parallels

Equator

PrimeMeridian



One exampleof a great circle

N

S

Greenwich meridian

(longitude 0°)

Equator(latitude 0°)

A great circle is any circle whose

plane passes through the Earth’s

center, no matter what direction.



What is the significance of the

great circle in navigation?



What is the significance of the

great circle in navigation?

The shortest distance between

two points on the Earth lies along

the path of a great circle passingthrough those two points.



Any unbroken part of thecircumference of a circle or

other curved line

Arc



The distance around a circular area

Circumference


http://slidepdf.com/reader/full/introtonavigationweb-110119151222-phpapp02 18/269What is the circumference of the Equator?



One exampleof a great circle

N

S

Greenwich meridian(longitude 0°)

Equator(latitude 0°)

Center ofThe Earth

360°360°

Regardless of the

size of the circle,the circumference

has 360°.



1°= 60 minutes

1 minute = 60 seconds

360°



Measurement along a meridianor parallel is expressed in termsof degrees, minutes, and seconds

of arc (the curve of the circle).



0°

0°

The Greenwich meridian is numbered0, or 0°, and is called the prime

meridian.

Greenwich RoyalObservatory



The meridian running throughGreenwich, England, from which

longitude east and west is measured

Prime Meridian



NORTH

POLE

INTERNATIONAL DATE LINE

PRIME MERIDIAN



International Date Line

180°InternationalDate Line

Old Date

New Date

New Day

Old Day

Noon

Midnight

International

Date Line

0°PrimeMeridian

Eastern



Equator

Western Hemisphere

Eastern

Hemisphere International

Date Line

PacificOcean

Prime



Meridians (longitude lines) between the

prime meridian and 180th meridian are

numbered 0°to 180°east (E) or west (W).

Meridians

PrimeMeridian

0°Longitude



Measurement of position east or westfrom the prime meridian

Longitude



The distance of arc east (E) or west (W)

of the prime meridian, measured along

a parallel

Longitude

PrimeMeridian

Greenwich

W E



Longitude Lines



Measurement of position north orsouth of the equator

Latitude

Latitude



Latitude

The distance of arc north (N) orsouth (S) of the equator, measured

along a meridian

Latitude Longitude



Grid system of latitude and longitude

lines

Latitude Longitude

Primemeridian

Equator



LATITUDE LONGITUDE

EARTH’S

GRID

90°90°

Remember!



NorthLatitude

SouthPole

NorthPole

WestLongitude

EastLongitude

Remember!

SouthLatitude

• Latitude is always measured north

or south from 0°through 90°

• Longitude is always measured eastor west from 0°through 180°





Express latitudeand longitude in

degrees, minutes,

and seconds.

Washington, D.C.

38°58'52"Nlatitude

77°01'12"Wlongitude

W hi gt D C



Washington, D.C.

38°59'N latitude

77°01'W longitude

This is spoken

as thirty-eightdegrees,

fifty-nine

minutes north,seventy-seven

degrees, one

minute west.

W hi D C



Washington, D.C.

38°58'52"Nlatitude

77°01'12"Wlongitude

Seconds are usedonly if very exactlocations are

required.



One minute of arc measured alongthe equator, or any other great

circle

Nautical Mile

6 865 Nautical Miles



6,865 Nautical Miles

6,888Nautical Miles

Equatorial Diameter - 6,888 Nautical Miles

Polar Diameter - 6,865 Nautical Miles



Comparison of a Statute Mileto a Nautical Mile

NAUTICAL MILE = 6,076 FEET OR 2,000 YARDS

STATUTE MILE = 5,280 FEET OR 1760 YARDS

0 500 1000 1500 2000

YARDS



Dividers

Distance on a chart is measured along

the meridian, using a tool called dividers.



Measuring Distance

P



30 NauticalMiles

52 NauticalMiles

60 Nautical

Miles

60°

30°

0°

P

Length of a Degree of Longitude at

Various Latitudes

Parallel



Distances are notmeasured on

parallels of latitude,

because one minuteequals one nautical

mile only along the

equator.

Dividers

Remember!



1 knot = 1 nautical mile per hour



Origin of the term knot

An old sailing day’s log for measuring

the speed of a vessel

Chip Log

True Nautical Direction



True Nautical Direction

Measured from true north (North Pole)

as located on a globe



32-point Compass



The four primary directions of thecompass; the north, south, east,

and west points

Cardinal Points

Cardinal Directions



North, South, East, West:

the four primary directions

of the compass

Cardinal Directions



On the compass rose above, only northis filled in. Fill in the rest of the points

on the compass, going clockwise, using

the standard abbreviations.



On the compass rose above, only northis filled in. Fill in the rest of the points

on the compass, going clockwise, using

the standard abbreviations.



Express nautical directions in

three digits:

065°(Zero six five degrees)

090°(Zero nine zero degrees)



Course – Direction the ship is steered

through the water

Heading – Direction the ship is facing



MAGNETIC COMPASS

Magnetic compassesgive direction relativeto magnetic north.

GYROCOMPASS

Gyrocompassesreference truenorth.



Navigational compass containing agyroscope, that, when adjusted forlatitude and speed, shows true northor communicates this information

to one or more gyro repeaters.

Gyrocompass

TRUEMAGNETIC



TRUENORTH

MAGNETICNORTH

Magnetic Compass



g p

A compass having a magnetizedneedle generally in line with the

magnetic poles of the Earth

NORTHMAGNETIC



United States

Canada

MAGNETICPOLE

Magnetic compasses point to theEarth’s northernmost magnetic pole,

located in northern Canada.

V i i A l



Difference between magnetic and truenorth in degrees

Variation Angle

How Variation Affects the Compass



VariationNorth Pole

Remember, variation changesdepending on your position relative

to magnetic north.

o a at o ects t e Co passMagnetic North



To convert from magnetic to true,

just add or subtract the variation

at your location to the magneticbearing.

Remember — Westerly variationsare subtracted, and easterly

variations are added.

Converting Direction

Example of Converting Direction



p g

If your ship was heading 080°magneticin a region where the variation was10°East, what is the true heading?




p g

If your ship was heading 080°magneticin a region where the variation was10°East, the true heading would be

080°+ 10°, or 090°true.




If your ship was heading 270°true in aregion where the variation was 10°East,

what is the magnetic heading?





If your ship was heading 270°true in aregion where the variation was 10°East,

the true heading would be 270° – 10°,

or 260°magnetic heading.


B i



The direction of an object from anobserver, measured clockwise in one

of three standard ways:

• True bearing

• Magnetic bearing• Relative bearing

Bearing



TN

True Bearing

090°TRUE

BEARING

Light

House

True Bearing



Bearing using true north as thereference

True Bearing

TRUE NORTHMAGNETIC



Difference between true and magnetic bearing

TRUE NORTHNORTH

Light

House

Magnetic Bearing



The direction of an object measuredclockwise from magnetic north

Magnetic Bearing



TN

Relative Bearing

RELATIVE

BEARING030°

Light

House

Relative Bearing



The direction of an object measuredclockwise from the ship’s head (bow)

Relative Bearing



When recording a bearing, assume it to

be a true bearing unless followed by theletters M or R.

030°M means 30°right of magnetic north

030°R means 30°off the starboard bow



Objects seen by lookouts are reported

in terms of relative bearing by degrees.

Relative Bearings



• Dead ahead, or bow – 000°R• Starboard beam – 090°R• Dead astern – 180°R

• Port beam – 270°R



To emphasize that it is a true bearing,the letter T (for example 030°T) follows

the three-digit true bearing, spoken

―030 degrees true.‖

TN



True Bearing = Relative Bearing + True Heading

(Subtract 360°if sum is greater than 360°)

090°TRUE

BEARING

RELATIVEBEARING

030°

LightHouse

Nautical Chart



Type of map used to navigate onwater

Nautical Chart



Hydrography



Science of measurement, description,and mapping of the Earth’s surfacewaters, with special reference to their

use for navigation

Hydrographic informationgiven on a chart includes:



• Water depths• Nature of bottom• Overhead obstructions• Navigation aids; buoys,

lights, and anchorages

given on a chart includes:



Globe

Impossible to

work navigation

problems orchart courses

Chart

Necessary to

work navigationproblems



Makers of maps and charts who use

math to work out chart projection

techniques

Cartographers

It is necessary



It is necessary

to convert the

round surface ofthe globe to one

that is flat and

two-dimensional(having only

length andwidth)—to

a flat piece of

paper on which achart is drawn.



Chart projections

C y l i n

d r i c a l

M e r

c a t o r

C o n i c a l

P e r s p e c t i v e C

o n i c

P l a n a r

O

r t h o g r a p h i c

Chart Projection



Flat surface representative of theEarth

Chart Projection



Mercator Projection

The best-known map or chart projection

Mercator Projection



Earth is projected onto acylinder-shaped piece of paper,

wrapped around the globe at theequator

Mercator Projection





A projection on which any rhumb line is shownas a straight line, used chiefly in navigation,though the scale varies with latitude and aerialsize and the shape of large areas are greatly

distorted

Conformal Projection

Great Circle

Track Rhumb Line

Rhumb Line



A curve on the surface of a spherethat cuts all meridians at the same

angle; the path taken by a vessel oraircraft that maintains a constantcompass direction

Rhumb Line





Small scales

are used todepict largeareas on a

chart, andlarge scales

are used to

depict smallareas.

Measuring distance on a chart



If an inch on the chart represents 50 miles,

what would five inches represent?

Measuring distance on a chart



If an inch on the chart represents 50 miles,

what would five inches represent?

250 Miles



Nautical Sailing



Types of Charts

Harbor

Nautical charts have information forsafe navigation, such as:



• Symbols, figures, and abbreviations• Depth of water • Type of bottom

• Navigational aids

g ,



Harbor charts are large-scale charts thatshow harbors and their approaches in

detail

Coastalcharts are



charts areintermediate-

scale chartsused tonavigate a

vessel whoseposition maybe determinedby landmarks

and lights,buoys, orsoundings

offshore

Sounding



The act of measuring the depth of anarea of water

Sounding



General

ocean sailingcharts aresmall-scalechartsshowing theapproachesto large

areas of thecoast.



INTRODUCTION TO NAVIGATION

End of Part 1



INTRODUCTION TO NAVIGATION

Part 2



Depths ofwater may

be given infeet, fathoms,or meters.

Fathom (of depth)



A unit of length equal to six feet(1.8 meters); used chiefly in nautical

measurements

( p )

Plotting



g

Plotting



In order to use the nautical chart for

navigating, you must know somethingabout how courses, bearings, andlines of position are plotted on it.



Parallel Rulers

Parallel Rulers



A pair of straightedges connected bytwo pivoted crosspieces of equal

length so as to be parallel at all times;used for various navigationalpurposes, especially for transferring

the bearing of a plotted course to acompass rose



Protractor

An instrument having a graduated arcfor plotting or measuring angles



Three-Arm

Protractor

Parallel Motion

Protractor (PMP)



Measuring

Distance on aMercator Chart

Fix (position)



Accurate position determined withoutuse of any previous position, using

visual, electronic, or celestialobservation

(p )



A line indicating

a series of possiblepositions of a ship

as a result of

observation ormeasurement

Line of Position

(LOP)

SPIRE



Lines of Position

CAPE

RANGE BEARING

TANGENT

DISTANCE ARC

Bearing Lines of Position



Lines corresponding to the bearingsare plotted on the chart. They are

labeled with the 4-digit time of

observation above the line

Visual Range



Two landmarks or navigation aids areobserved in line, one behind the other

RearMarker



Visual RangeRear Marker

Front Marker

Front

Marker



A circular line of position

Distance Arc



Devices used to

measure distanceto a landmark

Radar Stadimeter

Sextant

Stadimeter



Optical distance-measuring device

that measures angles to determinedistance to an object using as a

reference the distance to an object ofknown height



Stadimeter

Sextant



An astronomical instrument used todetermine latitude and longitude at

sea by measuring angular distances,especially the altitudes of Sun, Moon,and stars

Sextant





Most commonly used

Obtain a fix with these combinations

of lines of position:

• Two or more lines of bearing

• A distance arc and a line of bearing• Two or more distance arcs

• A visual range and a distance arc

• A visual range and a line of bearing• Two simultaneous visual ranges



A fix from twocrossed bearings

TOWER

1545

DOUBLE POINT



A fix by a

bearing and

distance fromthe same object

1314

LIGHT

SMITHPOINT



A fix from three

intersectingbearings

HALL REEF LIGHT

JONES

BLUFF

LIGHTW



A fix from twovisual ranges

LIGHT

X

LIGHTW2152

Visual Fix



Electronic/Celestial Fix

Dead Reckoning Position

Estimated Position

Plotting Symbols

LIGHTHOUSE



1300 FIX

1245 FIX

TOWER

Marking Ship’s Fix

FACTORY

LIGHTHOUSE



The determinationof position by

visual means

Piloting

Piloting



The determination of the course or

position of a ship or airplane by anyof various navigational methods or

devices

CompassNavigation Aids



Fathometer

Stadimeter

Radar

Buoy

Lighthouse

Bearing Circle

Chart

Echo sounder (Fathometer)



Sonic device used to measure waterdepth

Fathometer





Echo Sounder

Sound Ranging



SONAR (S0und NAvigation

and Ranging)

A method for determining the distancebetween a point and the position of a

sound source by measuring the timelapse between the origin of the soundand its arrival at the point



D=1/2 t x 4,800 feet per second

In piloting, soundings are usuallytaken every 5 minutes.

A f h



A fathometer may

establish a fixwhen a navigatorhas a chart

showing accuratebottom contours,

but in practice it

usually serves asa check.



Electronic navigation is

a form of piloting

Electronic Navigation



• Equipment malfunction

• Insufficient coverage

Disadvantages

• Unaffected by weather

• Determines ship position electronically

Advantages

RADAR



RAdio Detection And Ranging

RADAR



Navigation system using reflectedpulses of energy







Disadvantage of radar, as a navigationalaid, is that maximum range is currently

limited to slightly more than line of sight



Use Reliable Radar Targets

Lighthouse



Radar System

PIPS



Targets appear on the scope as

bright spots of light called pips



The most common scope used is a planposition indicator (PPI), which gives abird’s eye view of the radar coverage

area the transmitting ship in the center





• Very accurate and rapid

• Used to locate and track storms

• Very important for ship safety

Loran



Long Range Navigation

Loran



Long range navigation system usingradio signals



Loran is a systemof radio signals

broadcast bystations of known

position.



GPS Satellites



The newest electronic navigation system

is the Global Positioning System (GPS)

Satellite Navigation



GPS Navigation





GPS is used for a wide variety of land

navigation purposes, including positionand direction-finding in many new cars

and golf carts.



Differential GPS



Enhancement by to basic GPS: corrections topositioning information is determined by land-based receivers and transmitted to users.Capable of accuracy to within + 1 meter.

Ship’s Inertial NavigationSystem (SINS)



Provides accurate and continuous

dead reckoning (DR) positions



SINS gives ships an accurate and

continuous dead reckoning positionusing three gyroscopes to determinelatitude, vertical, and longitude with

great accuracy







The widespread availability of GPS is

fast making celestial navigation at sea

a vanishing art





HORIZONMIRROR

INDEX MIRROR

TELESCOPE

LENSHOODINDEX ARM



VERNIERSCALE

MICROMETERSCREWDRUM SCALE

ARCSCALE

Reading the Vernier Scale

Sextant — Nomenclature

Dead Reckoning



Calculation of one's position on thebasis of distance run on various

headings since the last preciselyobserved position, with as accurateallowance as possible being made for

wind, currents, compass errors

Visual Fix



Electronic/Celestial Fix

Dead Reckoning Position

Estimated Position

Plotting Symbols

FIXDR POSITION

DESTINATION



DEAD RECKONING TRACK1200

S d D if



Set and Drift

Set – The direction in which a ship

is forced by wind and current

Drift – The speed of that force in

knots





A line is drawn from the fix on the

ship’s course of 073°. Course is

l b l d b th li d th



labeled above the line, and thespeed of 15 knots is labeled below

the line.







Th t i l b l d ―1300DR ‖



The spot is labeled ―1300DR.‖



Using dividers, mark a spot 7½

miles from the 1300 DR position



along the direction the ship issteaming.



Label position 1330DR, anddraw a new course line in thedirection of 117°.











At sea, the navigator will use celestial or

electronic means to get positive fixes atleast every morning, noon, and evening.





Currently, electronic plotters incorporate

continuous fix updates received fromGPS, then project current ship’s positionand the DR track onto an electronic chartprojection on a computer screen.

Define navigation.

Q.1.



Define navigation.

Q.1.



The art and science by whichmariners find their ship'sposition and guide it safely

from one point to another

A.1.



What is a chart?

Q.2.



A type of map used to navigateon water

A.2.

What are the imaginary linesthat run through the poles andaround the Earth?

Q.3.



around the Earth?

What are the imaginary linesthat run through the poles andaround the Earth?

Q.3.



around the Earth?

Meridians or lines of longitudeA.3.

What divides the Earth into thenorthern and southernhemispheres?

Q.4.



hemispheres?

What divides the Earth into thenorthern and southernhemispheres?

Q.4.



hemispheres?

The EquatorA.4.





Are all meridians great circles?

Q.6.



Are all meridians great circles?

Q.6.



YesA.6.



What is the name given to themeridian on which the RoyalObservatory at Greenwich

Q.7.



Observatory at Greenwich,England, is located?

The Prime MeridianA.7.

Do parallel and latitudinal linesrun in the same direction?

Q.8.



Do parallel and latitudinal linesrun in the same direction?

Q.8.



YesA.8.

Navigators determine theirship's position using whatcoordinate system?

Q.9.



coordinate system?

Navigators determine theirship's position using whatcoordinate system?

Q.9.



coordinate system?

Latitude and LongitudeA.9.

If the latitude of the equator is0 degrees, what is the latitudeof the North Pole?

Q.10.



of the North Pole?



Latitude and longitude areexpressed in what units?

Q.11.







How many degrees are there ina circle?

Q.12.



360A.12.



Approximately how manyyards are in a nautical mile?

Q.13.



2000 yds.A.13.

What are meridians?

Q.14.



What are meridians?

Q.14.



Great Circles which passthrough the Earth’s poles

A.14.

In navigation what is a ―knot?‖

Q.15.



In navigation what is a ―knot?‖

Q.15.



A seagoing term meaning onenautical mile per hour

A.15.

How is direction expressed?

Q.16.



How is direction expressed?

Q.16.



As an angle between 000degrees and 359 degrees

A.16.

What are the cardinal points?

Q.17.



What are the cardinal points?

Q.17.



North, East, South, and WestA.17.

Define ―true bearing.‖

Q.18.



Define ―true bearing.‖

Q.18.



The direction of an objectmeasured clockwise from truenorth

A.18.

What does chart projectionentail?

Q.19.



What does chart projectionentail?

Q.19.



Projecting a three-dimensionalobject on a two-dimensional

plane

A.19.

What is the best-known map orchart projection called?

Q.20.



What is the best-known map orchart projection called?

Q.20.



Mercator projectionA.20.

What are the three basic typesof charts used by the Navy?

Q.21.



What are the three basic typesof charts used by the Navy?

Q.21.



a. Navigationalb. Harbor

c. General ocean sailing charts

A.21.

What is a cartographer?

Q.22.



What is a cartographer?

Q.22.



One who makes maps andcharts

A.22.

What is a fix?

Q.23.



What is a fix?

Q.23.



An accurate positiondetermined without referenceto any previous position. The

intersection of 2 or more linesof position.

A.23.

What is the difference betweendirections measured on agyrocompass and those

Q.24.



measured on a magneticcompass?

What is the difference betweendirections measured on agyrocompass and those

Q.24.



measured on a magneticcompass?

Directions measured on agyrocompass are relative to

true north, whereas directionsmeasured on a magneticcompass are relative tomagnetic north.

A.24.

How is distance on a Mercatorchart measured?

Q.25.



How is distance on a Mercatorchart measured?

Q.25.



On a flat surface along anymeridian where one minute of

latitude equals one nauticalmile

A.25.

If a half-inch on a chartrepresents 10 miles, how manyinches would represent 100

il ?

Q.26.



miles?

If a half-inch on a chartrepresents 10 miles, how manyinches would represent 100

il ?

Q.26.



miles?

Five inchesA.26.

What is the shortest distancebetween two points on aglobe?

Q.27.



What is the shortest distancebetween two points on aglobe?

Q.27.



An arc of a great circleA.27.

How many feet are in onefathom?

Q.28.



How many feet are in onefathom?

Q.28.



Six feetA.28.

What is a line of position(LOP)?

Q.29.



What is a line of position(LOP)?

Q.29.



A line drawn on a chart alongwhich a ship must be located,

based on a bearing or distancefrom an object or landmark

A.29.

A ship that is traveling southobserves another ship on arelative bearing of 041 degrees.

Wh t i th t b i t th t

Q.30.



What is the true bearing to thatship?

A ship that is traveling southobserves another ship on arelative bearing of 041 degrees.

Wh t i th t b i t th t

Q.30.



What is the true bearing to thatship?

221 degrees true(180 degrees + 041 degrees)

A.30.

A ship that is traveling northobserves another ship on arelative bearing of 041 degrees.

Wh ld th t hi

Q.31.



Where would you see that shipin relation to your ship?

A ship that is traveling northobserves another ship on arelative bearing of 041 degrees.

Where o ld o see that ship

Q.31.



Where would you see that shipin relation to your ship?

Off the starboard bowA.31.

A round body whose surface is at all

Sphere



A round body whose surface is at allpoints equidistant from the center

A great circle of the Earth passing

Meridian



A great circle of the Earth passingthrough the poles and any givenpoint on the Earth's surface

Lines of latitude with only the equator

Parallel



Lines of latitude with only the equatorbeing a great circle

A two pointed compass used for

Dividers



A two –pointed compass used fordividing lines and measuring

Compass Card



A circular card with magnets attachedto its underside, the face divided on its

rim into points of the compass, degreesclockwise from north, or both, andfloating or suspended from a pivot soas to rotate freely

Directional instrument that points to

Magnetic Compass



Directional instrument that points tothe north magnetic pole

Aligned with true north by means of aspinning gyroscope

Gyrocompass

The state of being misrepresented

Distortion



The state of being misrepresenteda false

Developmentof a Mercator

Projection





Sounding

LORAN CHART



Electronic navigation system using

Global Positioning System (GPS)



Electronic navigation system usingsatellites

Documents

introtonavigationweb-110119151222-phpapp02