Understanding Notices to Mariners

by Christopher O'Keeffe June 04, 2026

Understanding Notices to Mariners

Why nautical charts must be kept current — and how Notices to Mariners help skippers navigate with greater confidence.

A nautical chart is never truly finished.

The sea changes.

Sandbanks shift.

Channels are dredged.

Buoys are moved.

Lights are altered.

New hazards are discovered.

Wrecks are reported.

Maritime works begin.

Depth information is updated.

This is why professional mariners, serious recreational skippers, sailing schools, commercial operators, and chart users pay attention to Notices to Mariners.

A chart is only as good as the information it contains. Notices to Mariners are one of the key ways that charting authorities communicate important updates affecting navigation safety.

At Mapworld, our nautical chart collection includes official AUS charts, WA Department of Transport inshore charts, Imray cruising charts, tide tables, chart plotting tools, compasses, dividers, parallel rules, cruising guides, and marine navigation accessories. For anyone navigating Australian waters, understanding Notices to Mariners is part of understanding how charts stay reliable.

This guide explains what Notices to Mariners are, why they matter, and how they relate to the charts and navigation tools available through Mapworld.

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What Are Notices to Mariners?

Notices to Mariners, often abbreviated as NtM, are official updates issued to correct or update nautical charts and nautical publications.

They may advise mariners about:

• Changes to navigation lights

• New or moved buoys

• Removed or altered beacons

• New hazards

• Wrecks and obstructions

• Changes to depth information

• Shoaling or dredging

• Harbour works

• Marine construction

• Restricted areas

• Firing practice areas

• Changes to channels

• Updates to charted information

• Temporary hazards or events

In simple terms:

Notices to Mariners help keep charts current.

A nautical chart is a snapshot of marine information at a given time. Notices to Mariners are the update system that keeps that snapshot from becoming dangerously outdated.

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Why Notices to Mariners Matter

On land, an outdated road map can be inconvenient.

At sea, outdated chart information can be dangerous.

A navigation mark may have moved.

A light may have changed character.

A channel may have shifted.

A new obstruction may have been discovered.

A depth may no longer be reliable.

For vessels operating in shallow water, reef areas, harbours, estuaries, river entrances, ports, channels, or remote coastal regions, current chart information is essential.

Notices to Mariners help mariners answer critical questions:

• Is the chart still current?

• Have any lights or beacons changed?

• Are there temporary navigation warnings?

• Has the depth information been updated?

• Are there new hazards?

• Are there works or restricted areas in place?

• Has the official chart been corrected since publication?

Good seamanship requires more than owning a chart.

It requires using a current chart.

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Who Issues Notices to Mariners in Australia?

In Australian waters, official chart corrections are issued by the Australian Hydrographic Office.

The Australian Hydrographic Office is Australia’s national charting authority and publishes official AUS nautical charts for Australian waters.

Australian Notices to Mariners are published regularly and provide the authority for correcting Australian paper nautical charts and nautical publications.

State authorities may also issue local notices or temporary notices relevant to recreational and inshore boating. In Western Australia, for example, the Department of Transport provides detailed inshore charts and associated Notices to Mariners for WA coastal waters.

For skippers, the practical message is clear:

Use official charts and keep them corrected.

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Notices to Mariners and Official AUS Charts

Official AUS charts are the standard nautical charts for Australian waters.

They are used by:

• Commercial vessels

• Sailing schools

• Marine training organisations

• Serious recreational mariners

• Government and maritime agencies

• Professional navigators

• Offshore cruisers

Mapworld’s nautical chart collection includes official Australian Hydrographic Service AUS-numbered charts in paper and laminated formats. Mapworld’s AUS chart listings emphasise that official charts are corrected to the latest Notices to Mariners at the time of supply.

This is one of the most important reasons to buy charts from a specialist nautical chart supplier.

When you purchase an official AUS chart from Mapworld, you are not simply buying a sheet of paper.

You are buying a chart supplied with currency and correction in mind.

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Notices to Mariners and WA Department of Transport Inshore Charts

Western Australia has one of the most diverse and challenging recreational boating coastlines in the world.

From Perth waters and Rottnest Island to Jurien Bay, Shark Bay, Exmouth, the Abrolhos, the Pilbara and the Kimberley, WA skippers often operate in waters where local detail matters.

The WA Department of Transport produces detailed inshore charts for recreational and local commercial vessels.

These charts are especially useful for:

• Trailer boat owners

• Recreational fishers

• Local skippers

• Coastal cruisers

• Marine training

• Inshore navigation

• Harbour and estuary use

Mapworld’s WA inshore chart range is particularly popular because many charts are available in practical formats such as:

• Paper

• Waterproof synthetic material

• Laminated write-on/wipe-off versions

For WA boaters, Notices to Mariners and local navigational warnings are an important part of staying up to date. Even familiar waters can change, especially around channels, sandbanks, moorings, navigation marks, works and local hazards.

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Permanent, Temporary and Preliminary Notices

Not all Notices to Mariners are the same.

In general, mariners may encounter different types of notices.

Permanent Notices

These correct a chart or publication permanently.

Examples may include:

• A new buoy added to a chart

• A light characteristic changed

• A depth correction

• A wreck added

• A navigation aid removed

• A shoreline or harbour update

Permanent corrections are applied to the chart so that it reflects the updated information.

Temporary Notices

Temporary Notices advise mariners of short-term conditions or hazards.

Examples may include:

• Marine works

• temporary exclusion zones

• dredging

• events

• temporary navigation changes

• hazards expected to exist for a limited time

Temporary Notices are important because they may affect a planned trip even if the printed chart appears otherwise correct.

Preliminary Notices

Preliminary Notices advise mariners of changes that are expected or planned, but where full chart correction may not yet be finalised.

These can help navigators stay informed about developing changes in a maritime area.

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What Kind of Chart Information Gets Updated?

Notices to Mariners can affect almost every part of a nautical chart.

Common corrections include:

Depths and Soundings

Depths may be amended after new surveys, dredging, shoaling or changed seabed conditions.

Navigation Aids

Buoys, beacons, marks and lights may be added, moved, removed or altered.

Lights

Light colour, range, height or flash pattern may change.

Wrecks and Obstructions

New hazards may be discovered and charted.

Channels

Channels may be dredged, shifted, renamed, restricted or altered.

Restricted Areas

Marine parks, exclusion zones, firing areas, construction areas or port limits may change.

Harbour Works

New wharves, marinas, breakwaters, dredging works or infrastructure may affect charted information.

Chart Notes

Important cautionary notes, warnings or local instructions may be added or amended.

For a navigator, each correction is a reminder that the sea is dynamic and charts require maintenance.

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How Paper Charts Are Corrected

Paper chart correction is a traditional navigation skill.

Depending on the notice, a correction may involve:

• Adding a symbol

• Deleting a symbol

• Amending a light description

• Changing a depth

• Adding a cautionary note

• Updating a charted feature

• Applying a printed block correction

• Recording the correction in a chart correction log

Professional mariners usually maintain correction records to show that charts have been kept up to date.

For recreational users, the process may be simpler, but the principle is the same:

Know whether your chart is current and understand any changes affecting your area.

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Why Chart Currency Is Especially Important in Australia

Australia’s coastline is enormous and varied.

It includes:

• Coral reefs

• tidal flats

• shifting sandbanks

• river bars

• busy commercial ports

• remote anchorages

• offshore islands

• shallow estuaries

• exposed coastlines

• dredged channels

• strong tidal regions

• marine infrastructure

In some areas, the seabed and navigation environment can change significantly.

This is particularly important around:

• Port approaches

• river mouths

• bar crossings

• reef systems

• dredged channels

• boating harbours

• commercial shipping lanes

• cyclone-prone areas

• remote northern waters

Current chart information helps skippers understand not only where they are, but what may have changed since the chart was first published.

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Notices to Mariners and Navigational Aids

Navigational aids are essential reference points for mariners.

These include:

• Lighthouses

• buoys

• beacons

• cardinal marks

• lateral marks

• special marks

• leading lights

• sector lights

• day marks

• isolated danger marks

A chart may show the location and characteristics of these aids.

But if a navigation aid is moved, removed, altered, damaged, extinguished or temporarily replaced, the chart must be updated.

Notices to Mariners are one of the ways these changes are communicated.

For example, a notice may advise that:

• A buoy has been repositioned

• A light is temporarily extinguished

• A beacon has been destroyed

• A new marker has been established

• A channel mark has changed

• A leading light has altered its characteristics

This is why skippers should never assume that navigation marks are unchanged simply because they appear on an older chart.

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Mapworld’s Nautical Collection: Charts and Tools for Safer Planning

Mapworld’s nautical collection is built around the practical needs of Australian mariners.

It includes:

Official AUS Charts

For Australian coastal, offshore, port and passage navigation.

These are the key charts for serious marine navigation and are corrected to the latest Notices to Mariners at the time of supply.

WA Department of Transport Inshore Charts

Detailed local charts for Western Australian recreational and local commercial boating areas.

Available in practical formats including paper, waterproof and laminated versions.

Imray Cruising Charts

International cruising charts widely used by sailors and small-craft navigators.

Excellent for overseas cruising regions and passage planning.

Tide Tables

Essential for planning passages, bar crossings, anchoring, drying areas and shallow-water navigation.

Plotting Tools

Including parallel rules, dividers, chart plotters and other traditional navigation aids.

Marine Compasses

For steering, bearings and traditional navigation.

Cruising Guides

Practical regional information that complements chart use.

A chart is strongest when used as part of a complete navigation system.

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Paper, Laminated or Waterproof Charts?

Mapworld supplies many nautical charts in different formats, depending on the chart series and product.

Paper Charts

Best for:

• Traditional chart table use

• official correction practice

• plotting courses

• passage planning

• long-term storage

Paper charts remain the traditional standard for formal navigation work.

Laminated Charts

Best for:

• Cockpit use

• repeated handling

• recreational boating

• fishing trips

• training environments

• write-on/wipe-off planning

Laminated charts are especially practical for recreational skippers who want durability and the ability to mark routes, fishing spots or notes.

Waterproof Charts

Best for:

• Open boats

• wet decks

• fishing vessels

• exposed conditions

• repeated folding and handling

Waterproof charts are extremely useful where ordinary paper would quickly suffer from salt spray, rain or wet hands.

The navigational information matters, but so does the format. A chart that survives real boating conditions is far more likely to be used properly.

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Notices to Mariners and Electronic Charts

Modern vessels may use electronic chartplotters, ECDIS, apps or digital chart products.

These systems also require updating.

Electronic updates may be applied differently from paper chart corrections, but the principle is the same:

Navigation information must be kept current.

For recreational skippers using both digital and paper charts, it is worth remembering:

• Digital charts need updates.

• Paper charts need corrections.

• Apps may vary in update frequency.

• GPS position alone does not replace chart awareness.

• Notices and warnings may affect your trip even if your device shows a route.

Good seamanship means checking multiple sources before departure.

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How Skippers Should Use Notices to Mariners

A practical routine might look like this:

1. Identify Your Chart

Check the chart number and edition.

2. Check the Latest Notices

Use the relevant hydrographic or state authority source to identify Notices affecting your chart or area.

3. Review Temporary Notices

Temporary works, events, hazards and warnings can affect your passage even if the printed chart is otherwise current.

4. Correct the Chart if Required

Apply permanent corrections according to the official instructions.

5. Record Corrections

Keep a correction log if required, especially for commercial or training use.

6. Check Local Conditions

Notices to Mariners are essential, but also check weather, tides, local warnings, bar conditions, port notices and marine safety information.

7. Use Good Seamanship

A corrected chart is not a substitute for lookout, depth awareness, local knowledge, sounder use, safe speed and sound judgement.

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Notices to Mariners for Recreational Boaters

Some recreational boaters assume Notices to Mariners are only for commercial ships.

That is a mistake.

Recreational skippers also benefit from current navigation information.

This is especially true for:

• Trailer boats

• sailing yachts

• fishing vessels

• cruising boats

• jet skis

• dive boats

• club racing fleets

• training vessels

If you are navigating using a chart, then updates to that chart matter.

Even a local day trip can be affected by:

• A temporary exclusion zone

• a missing buoy

• a changed channel mark

• dredging activity

• a new obstruction

• local marine works

• a changed light

Recreational boating is safer when skippers take chart currency seriously.

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Notices to Mariners and Marine Training

For sailing schools, marine colleges, yacht clubs and navigation courses, Notices to Mariners are an important teaching topic.

Students should understand:

• Why charts are corrected

• How navigation aids are updated

• How to identify chart edition information

• How to check for current notices

• How to apply basic chart corrections

• Why temporary warnings matter

• How paper and electronic chart updates differ

Mapworld’s nautical collection supports marine education through official charts, laminated training charts, plotting tools, compasses, dividers, parallel rules and other navigation aids.

Learning to read a chart is important.

Learning to keep it current is just as important.

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Navigational Aids That Work with Charts

A chart is only one part of traditional navigation.

Useful tools include:

Dividers

Used to measure distance on charts.

Parallel Rules

Used to transfer courses and bearings across the chart.

Breton Plotters and Course Plotters

Used to plot courses, bearings and angles.

Marine Compass

Used to steer courses and take bearings.

Pencil and Eraser

Still essential at the chart table.

Tide Tables

Used to calculate water depth and tidal timing.

Cruising Guides

Provide local context and practical passage information.

Mapworld stocks a range of marine navigation tools that help turn chart information into practical navigation decisions.

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Why Buying Current Charts Matters

An old chart may still look beautiful.

It may still show coastlines, harbours and familiar place names.

But for navigation, old information can be risky.

A current chart provides:

• Updated depths

• corrected navigation aids

• current hazards

• amended channels

• revised notes

• corrected charted details

This is why Mapworld places strong emphasis on supplying official AUS charts corrected to the latest Notices to Mariners at the time of dispatch.

For historical display, old charts are wonderful.

For navigation, currency matters.

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Historical Charts vs Navigational Charts

Mapworld also offers beautiful historical nautical charts.

These are superb for:

• wall art

• education

• maritime history

• coastal homes

• boardrooms

• collectors

• gifts

But historical charts should never be confused with current navigation charts.

A historical chart may show how a harbour, reef, coast or island group was understood in the past.

A current nautical chart is designed to support present-day navigation.

Both are valuable.

But they serve very different purposes.

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The Mapworld Recommendation

If you are navigating Australian waters, use:

• The correct official chart for your area

• The latest edition available

• Charts corrected to the latest Notices to Mariners

• Relevant temporary notices and local warnings

• Tide tables

• Proper plotting tools

• A reliable compass

• Sound judgement and good seamanship

If you are boating in Western Australian inshore waters, consider WA Department of Transport inshore charts in paper, waterproof or laminated versions for detailed recreational coverage.

If you are cruising internationally, consider Imray cruising charts and relevant local Notices to Mariners.

For regular onboard use, laminated and waterproof formats can make charts easier to handle in real conditions.

For formal navigation, corrected paper charts remain central.

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Final Thoughts

Notices to Mariners may not be glamorous.

They are not the first thing most people think about when planning a day on the water.

But they are one of the quiet foundations of safe navigation.

They remind us that charts are living documents.

They change because the sea changes.

Navigation marks change.

Channels change.

Hazards change.

Harbours change.

And responsible skippers keep up.

At Mapworld, we believe a good chart is one of the most important tools aboard any vessel. But a good chart should also be current, understood and used properly.

Because safe navigation is not simply knowing where you are.

It is knowing what has changed around you.

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Frequently Asked Questions

What are Notices to Mariners?

Notices to Mariners are official updates used to correct nautical charts and publications. They may include changes to depths, navigation aids, hazards, lights, channels, restricted areas and other important marine information.

Why are Notices to Mariners important?

They help keep charts current. At sea, outdated chart information can create real navigation risk, especially in shallow water, channels, ports, reef areas and busy boating regions.

Who issues Notices to Mariners in Australia?

Australian Notices to Mariners are issued by the Australian Hydrographic Office for official Australian charts and publications. State maritime authorities may also issue local or temporary notices relevant to inshore and recreational boating.

Are Mapworld AUS charts corrected?

Mapworld supplies official AUS charts corrected to the latest Notices to Mariners at the time of dispatch.

Do recreational boaters need to check Notices to Mariners?

Yes. Recreational skippers can be affected by changed navigation marks, temporary hazards, marine works, exclusion zones, altered lights and other updates.

What is the difference between permanent and temporary notices?

Permanent notices correct chart information for ongoing use. Temporary notices advise mariners of short-term changes, hazards, events or restrictions.

Are WA inshore charts affected by Notices to Mariners?

Yes. WA Department of Transport provides chart information and notices for Western Australian inshore waters. Skippers should check current notices and warnings before boating.

Do electronic charts need Notices to Mariners?

Electronic charts also require updating. Updates may be applied differently from paper chart corrections, but the need for current navigation information remains the same.

What tools do I need for paper chart navigation?

Useful tools include dividers, parallel rules, plotters, pencils, erasers, tide tables, marine compass and current nautical charts.

Can historical charts be used for navigation?

No. Historical charts are for display, education and collecting. Modern navigation should always use current official charts and current Notices to Mariners.

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