Master of vessels less than 24mtrs & Master 5 Navigation

(Includes extracts courtesy of A.N.T.A, Ranger Hope © 2008-2016)

 

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Charts and Publications

 

Navigational Equipment

 

Application of Compass Errors

 

Vessel Positioning Techniques

 

Distance off

 

Tide Calculations

 

Planning Safe Courses

 

Electronic Aids to Navigation

 

Amplitudes, Azimuths and Plane Sailing

 

 

 

 

 

 

 

 

 

 

Charts and Publications

Position and Direction on the Earth Surface

Chartwork

Latitude

Longitude

Direction

Distance

Properties of a Mercator

Locating and Identifying Navigational Charts and publications

Sailing Directions

Admiralty list of lights

Tide Tables

Notices to Mariners

Navigational Warnings

Chart Catalogues

Types of Charts and information provided

Chart Categories

Chart Information

Defining Position

Symbols and Abbreviations

 

 

Position and direction on the Earth’s surface

In order to define the exact position on the Earth’s surface it is necessary to have two co-ordinates.  Those customarily used are Latitude and Longitude.  Position may also be expressed in relation to a known geographical position.

Example 15 miles East of Burnett Head Lighthouse.

Both Latitude and Longitude are given in the units

DEGREES (°) MINUTES ( ¢  ) SECONDS ( ²  )

 

Latitude

There is one plane which perfectly bisects the earth midway between the two poles.  The line formed where this place meets the surface of the earth is called the equator.

All lines on the earth’s surface which run parallel to the equator are called parallels of latitude.  They are named north or south depending on which side of the equator they lie.

Latitude is measured by the angle at the earth’s centre between the place in question and the equator.  Latitude is therefore between 0° and 90°, north or south.

Angle BAC (or arc BC) is the latitude of C

 

 

Figure 1.1:  Definition of Latitude

 

 

 

 

 

Longitude

There are a great number of circles which pass through both poles and form circles on the earth’s surface.  These circles cut the equator and all parallels of latitude at 90 degrees.  They are called meridians.  Unlike the measurement of

latitude there is no natural reference point.  The reference meridian selected is that which passes through the old observatory at Greenwich in England.  It is called the Greenwich, or Prime meridian.

 

All other meridians are named east or west, from 0° to 180°, depending on the angle at the earth’s centre between the prime meridian and the one in question.  This provides the second co-ordinate, called longitude.

 

The longitude of X and Y is the same, as is

the longitude of A and B.  (Note that the

angle could be measured at any point on the

earth’s axis, including either pole).

 

 

 

 

 

 

 

 Figure 1.2: Definition of Longitude

 

 

Direction

Direction is the position of one point relative to another, customarily expressed as the angular difference in degrees, usually from NORTH or the SHIP’S HEAD, without reference to the distance between them.

 

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Figure 1.3:  Definition of Direction

 

On the navigational chart the direction in which a place or object lies from the vessel is called the true bearing and is measured from NORTH (0°) in a clockwise direction through 360°.

 

 

Distance

Distance on the earth is customarily expressed in Nautical miles by Mariners, and is the spatial separation of two points, in this case A and B.

 

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Figure 1.4:  Definition of Distance

 

For most navigational purposes the nautical mile is considered to be the length of 1 minute of Latitude and this is the scale one should use.

 

NEVER use the Longitude scale to measure distance.


Properties of a Mercator Chart.

The navigator is required to find the following characteristics in a chart:

Coast lines should retain the same shape as they have on the Earth’s sphere.

The lines of Latitude and Longitude should be east - north and west - south respectively.  They should cross at right angles as on the sphere.

A straight line drawn on a chart between any two places should give the distance and direction between them.  The angle at which this line cuts any meridian should give the TRUE course to steer.

 

The chartmaker has the problem of representing the rounded surface of the earth on a flat piece of paper.  To some extent this is satisfied in the Mercator projection, but not without distortion of Land Mass sizes, unless they are near the Equator.

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Figure 1.5:  World Mercator Projection


 

Example    Greenland is smaller than Australia on the Globe, but appears on the Mercator projection as the same size.

 

The main feature of the Mercator projection is that both meridians and parallels are expanded at the same ratio with increased latitude.  Expansion is the same in all directions and angles are correctly shown.  Rhumb lines appear as straight lines, the directions of which can be measured directly on the chart (angle 2°).

Bearing and course lines are Rhumb lines.

Distances can be measured directly, for practical accuracy, but not by a single distance scale over the entire chart.

The latitude scale is customarily used to measure distances, the expansion of the scale being the same as that of distances at the same latitude.

 

 

 

 

 

Locating and Identifying Navigational Charts and Publications.

 

We will first consider the various publications.

Certain publications are necessary to supplement the information a navigator can obtain from the chart.

 

 

 

Sailing Directions (Pilots)

These are intended to be read in conjunction with the charts quoted in the text.  They are published by the Hydrographer of the Navy or by Local Government.  The latter generally being more up to date.

They need to be kept up to date by the latest supplement and Notice to Mariners.

An example of the title and contents is shown on the following page.


Sailing Directions (Pilots)

 

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Admiralty List of Lights

These give full details of all official navigational lights and are available from Hydrographic Office.

They are corrected from Australian Notices to Mariners issued fortnightly.  See an example of a cover sheet on the following page.

Each light within the book is given a number, Latitude and Longitude etc.

 

List of Lights

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Tide Tables

 

These are published annually by the Hydrographic Office covering all Australian Ports, Papua New Guinea and Solomon Islands.

Locally published tables are published by State Governments and often give       other useful information.

(Example)   Queensland Transport produce annually ‘The Official Tide Tables and Boating Safety Guide’

This covers tidal predictions, the weather, fishing guide etc.

Tidal calculations will be explained later in Outcome 5.

 

 

Notices to Mariners

 

These are issued in fortnightly editions, numbered consecutively, by the RAN Hydrographic Service.

They contain corrections for the following.

Charts

Sailing Directions (Pilots)

List of Lights

Admiralty List of Radio Signals

 

The following pages give examples of corrections from Edition 30 (1996.)

They can be obtained free of charge from the Custom House or Shipping Offices.

 

 


Australian Notices to Mariners

 

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Chart Correction

 

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List of Lights

 

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Admiralty List of Radio Signals

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Navigational Warnings

 

Contained within the Notices to Mariners are navigational warnings.

Two types of navigation warnings are originated by the Federal Sea Safety Centre and broadcast by Telstra Coast Radio Stations.

The first are NAVAREA which are long range warnings.

The second type is the AUSCOAST warning.

Examples of these are given on the following page.

 

Chart Catalogues

 

In Australian waters charts can be identified using 2 catalogue sheets.

Northern sheet covers from Port Clinton in Queensland to N.W. Cape in Western Australia.

Covered on the above sheet is Papua New Guinea and the Solomon Islands.

The Southern sheet covers the rest of Australia including Tasmania.

The sheets give the Chart Number, Title, Scale and Current Edition Date.

On the back of each sheet are various miscellaneous charts and publications.

 

Their numbers are:                                 Southern    AUS 5020B

                                                                Northern    AUS 5020A

 

The catalogue charts should not be used for navigation but are invaluable for planning a voyage and ordering charts and publications required.

 


Navigational Warnings

 

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Types of Charts and Information Provided

 

A nautical chart is a graphic representation, on a plane surface, of a navigable area on the earth’s surface. They are available both as paper charts and as electronic charts. They differ from a map in recording both position and elevations from survey with a reliability statement (zones of confidence). There will be an updating service provided for government charts to maintain their high accuracy. It is an essential tool of the navigator and without it a position cannot be fixed relative to navigation aids, the coastline or hidden dangers.

A chart will show the depth of water by soundings and depth contours, shoreline, topographic features, nature of the bottom, tidal streams, magnetic variation etc. for the area.

Chart categories.

 

World Charts

These are the smallest scales and are used to show Ocean Routes, Ocean Currents, Magnetic Variation.

Ocean Charts

These are the next scale and are typically 1=10,000,000, covering large areas such as the Indian Ocean, North Pacific etc.  The shoreline and topography is not shown in great detail.  Used for planning and position fixing on long ocean passages.

General Charts

Used for navigation where courses lie outside outlying reefs and shoals.  Typically 1:1,000,000 AUS423 Eddystone Point to Port Jackson.

Coastal Charts

Used for inshore navigation where courses lie inside outlying reefs and shoals.  Typically 1:150,000  AUS701 Vrilya Pt. to Duyfken Pt.

Plan Charts

Used for harbours and rivers giving great detail.  Typically AUS32 Cambridge Gulf 1:75,000 with insets of 1:37,500 Wyndham Approaches

1:7,500 Wyndham Wharf

 


Chart Information

 

Find a chart and identify the following information while reading the text.

Chart Number

The catalogue number of the issuing authority is shown in the lower right and upper left margins.

The number will be preceded by letters

Examples being           AUS........... Australian

                                     NZ.............  New Zealand

                                      B.A............ British Admiralty

                                     INT........... . International

 

 

 

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Figure 1.6:  Chart Number

 

 

Printing Date

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Figure 1.7:  Chart Printing Date

 

Appears in the upper right margin.


 

 

Dimensions

Appear in brackets in the lower right margin.

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Figure 1.8 Chart Dimensions

 

Title or Legend

This is placed in a position on the chart so that no essential navigational information is obscured often over land areas.

It usually includes.

Area Depicted

Survey Dates

Units of Sounding   -  Fathoms or Metres

Notes on Heights

Natural Scale

Projection                -  Mercator, Gnomonic

                                  -  Transverse Mercator

Frequently found under the tide, but may appear elsewhere if space so requires in Tidal information and Caution notes.

 

 

Publication

This appears in the centre bottom margin.  It may include new edition and large corrections.


 

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Figure 1.9:  Chart Title and Date of Publishing


Small Corrections

The year and correction number are placed in the lower left margin as they are entered on the chart from ‘Notices to Mariners’, a small section of which is shown in Figure 1.10.

Temporary and provisional notices should only be entered in pencil on the chart and their number never entered in the small correction area.

 

 

Before purchase you should ensure that the chart is corrected to the latest ‘Notices to Mariners’.

 

Charts need to be kept up to date by the Australian Notices to Mariners issued fortnightly.  Copies can be sighted free of charge from official Chart Agents and Custom Houses in major Queensland centres.

 

 

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 Figure 1.10:  Small Corrections


 

Defining Positions

 

Chart positions are defined by Latitude and Longitude or Bearing and Distance.

The Latitude scale is on the sides of the chart and used for distance measurement.

One minute of Latitude is equal to 1 nautical mile.  It also defines the position North or South of the equator.

 

 

 


Figure 1.11:  Latitude Scale

 

The Longitude scale is across the top and bottom of the chart and defines the position East or West of Greenwich.

 

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Figure 1.12:  Longitude Scale


To define position by bearing and distance we use the compass rose, Figure 1.13 for true bearing and the Latitude scale, Figure 1.14 for measuring distance. 

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Figure 1.13:  Compass Rose

 

 

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Figure 1.14:  Latitude Scale

 


Symbols and Abbreviations

 

All lines and symbols on a chart mean something and are contained in publication (5011 Symbols and Abbreviations). However, certain symbols and abbreviations the student should be able to recognise without reference to 5011.

 

Notably    Rocks, Wrecks and Obstructions

                IALA Buoys and Beacons

                Light Characteristics

The more common natural features to your area and certain areas of limitations.

 

The questions at the end of this outcome give an indication of the type of symbols and abbreviations the student should be able to recognise.

 

Particular attention should be paid to water depths and nature of the bottom.