(Extracts courtesy of A.N.T.A. publications, Ranger Hope © 2022

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Links to Study Workbooks:

Charts and Publications

Navigational Equipment

Compass Error

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






Mercator charts

Locating and Identifying Navigational Charts and publications

Sailing Directions

Admiralty list of lights

Tide Tables

Notices to Mariners

Maritime Safety Information


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 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




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: Definition of Latitude



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 2: Definition of Longitude



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 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 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 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 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 digitally and 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.




Notices to Mariners

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

They contain corrections for the following.


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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Maritime Safety Information

AMSA and the Bureau of Meteorology provide vessels with maritime safety information (MSI) about hazards and foreseeable dangers to safe navigation through Australia's marine environment. MSI is designed to give mariners information relating to:

navigational safety warnings
meteorological warnings
meteorological forecasts relevant to vessels within specified coastal areas
search and rescue information
other urgent safety related messages.
Most MSI is temporary, while others may remain relevant for several weeks and superseded by notices to mariners.

In Australia, MSI is provided via long range warnings (NAVAREA X and METAREA X warnings) and coastal warnings (AUSCOAST warnings, sea safety messages, and coastal wind warnings).

AUSCOAST warnings are broadcast to the relevant coastal areas as shown:


The primary method for promulgation of navigational warnings is via the Inmarsat SafetyNET system supplemented by HF radiotelephone broadcasts.

It is the responsibility of masters to ensure their Enhanced Group Call (EGC) and HF receivers are correctly configured, even while in port (if needed), to receive MSI appropriate to their intended voyage.

HF radiotelephone broadcasts are promulgated on the following schedule and frequencies from sites at Wiluna, WA and Charleville, QLD. It is important to test which frequencies and broadcast site (Charleville, QLD or Wiluna, WA) suit your listening requirements for time of day, month and season.

More at Maritime safety Information.





MASTREP Ship Reporting for the Australian Area
The Modernised Australian Ship Tracking and Reporting System (MASTREP) as described in Marine Order 63 Vessel
Reporting Systems, effective 1 January 2016, is used to track the location of vessels. Under this system:
• positional reporting for vessels is sourced from the vessel’s Automatic Identification System (AIS);
• Sailing Plans, Deviation Reports and Final Reports are not required;
• communications with vessels continue to be available through Inmarsat, HF, satellite telephony and other means;
• Special Reports are required to support AMSA’s role in shipping oversight and incident reporting management.
MASTREP is operated by the Australian Maritime Safety Authority (AMSA) as part of the services offered by the Joint
Rescue Coordination Centre (JRCC Australia). JRCC Australia is staffed 24 hours per day


More about MASTREP at AMSA.




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.


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 6:  Chart Number




Printing Date

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Figure 7: Chart Printing Date



Appears in the upper right margin.


Appear in brackets in the lower right margin.


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Figure 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.




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


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Figure 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 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 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 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 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 13: Compass Rose


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Figure 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.



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.