About Australian Notices to Mariners


Australian Notices to Mariners Editions

Australian Notices to Mariners are the authority for correcting paper navigational charts and paper nautical publications published by the Australian Hydrographic Office (AHO).

Australian Notices to Mariners are published by the AHO in 25 fortnightly editions each calendar year and are numbered from 1 onwards. They are issued to correct and maintain the following AHO published products:

  • AUS paper charts (coverage includes Australian, Papua New Guinea, Timor Leste and Australian Antarctic Territory waters)
  • SLB paper charts (coverage includes Solomon Islands)
  • Australian National Tide Tables (AHP11)
  • Mariner's Handbook for Australian Waters (AHP20)
It also notifies mariners of the release and withdrawal of AHO published navigational products.


eNotices is a free subscription service from the Australian Hydrographic Office which enables mariners to receive Notices to Mariners for charts and nautical publications by email. Users must subscribe to use the service on this web site. Users create their portfolio of charts and nautical publications by selecting from a scrollable list at subscription time. Then as Australian Notices to Mariners are published, subscribed users are automatically emailed only the Notices to Mariners that affect their portfolio of charts and publications.

It should be noted that eNotices do not include blocks, tracings or Part 1 of the Australian Notices to Mariners (charts and publications published or withdrawn). This allows eNotices email file sizes to remain small compared to the full fortnightly Australian Notice to Mariners, and therefore is more easily downloaded at sea.

To subscribe to this service go to the eNotices section of this web site.

Notices to Mariners for Electronic Hydrographic Products

AusENC has its own update service. For details see the AusENC section of this web site.

AusTides is occasionally updated by software updates. To download the latest updates see the ANTT & AusTides Updates section of this web site.

Types of Notices of Mariners

Australian Notices to Mariners are divided into the following sub-types:

  • Notices to Mariners (NTM) updates
  • Notices to Mariners Blocks and Notes
  • Preliminary Notices to Mariners (P)
  • Temporary Notices to Mariners (T)

Notices to Mariners Updates

A Notice to Mariners (NTM) is issued for the prompt dissemination of textual permanent navigational information considered important to safe navigation and which is not of a complex nature. These notices to mariners are also called Permanent Notices to Mariners.

Notices to Mariners Blocks and Notes

A Notice to Mariners Block is produced to assist the mariner to update their chart where there is significant new data important to safe navigation in a relatively small area, or where the volume of changes would clutter the chart unacceptably if amended by hand. Blocks are small sections of printed chart that are designed to be cut out and manually pasted onto the relevant chart.

Notes are also produced to assist the mariner to update their charts. Notes are printed versions of new or amended chart notes designed to be cut out and manually pasted on the relevant charts.

Preliminary Notices to Mariners (P)

A Preliminary Notice to Mariners (P) is issued where early promulgation to mariners is needed and:

  • Work will soon be taking place (such as a change to a navigation aid). A permanent NTM will be promulgated when the change is completed.
  • Information has been received, but is too complex or intensive to be promulgated by a permanent NTM. A precis of the overall changes together with information important to safe navigation is given in the (P) notice. Full details will be included in a new chart or new edition.

Temporary Notices to Mariners (T)

A Temporary Notice to Mariners (T) is issued where the information will remain valid only for a limited period. A (T) notice will not be initiated where the information will be valid for less than one month. In such circumstances this information may be promulgated as a Radio Navigation Warning or as a local notice to mariners.

Notices to Mariners Tracings

Notices to Mariners Tracings are produced to assist the mariner to update their charts. They are diagrams that provide guidance on how to apply Notices to Mariners updates that require accuracy in positioning them. They are overlaid on the chart and the position of each feature can be pricked through to the chart with a pin to enable the feature to be drawn in position. A set of tracings is available for each of the 25 published Australian Notices to Mariners Editions.

Cumulative Lists

A Cumulative List is produced to assist mariners to update their charts. It is published twice a year (in April and October) and lists the current edition date and all the Notices to Mariners updates that have affected each Australian Navigational Chart in the last two years. If a chart has not been affected by a notice during that period then the most recent notice, if any is shown. For more information or to view the latest list see the View Cumulative List section of this web site.

Note that mariners can look up the current edition date of a chart at any time of the year by accessing the Paper Chart List on the Australian Chart Index on this website. By selecting the ‘View’ option from this page, a list of applicable Notices to Mariner updates will be displayed.

Notices to Mariners as they relate to New Editions and New Charts

A New Edition of a chart is produced when there is a large amount of new information or a significant amount of accumulated information for a chart that is non-safety critical. New Editions incorporate all NTMs issued for the previous edition. New editions are promulgated by NTMs and supersede previous editions of the chart that should be replaced. NTMs issued after a New Edition is released should not be applied to the previous edition as they are applicable only to the New Edition ’s datum and imbedded information.

A New Chart is issued if it covers an area not previously charted to the scale shown, or it covers a different area to the existing chart, or it introduces new depth units (for example a conversion from imperial to metric units). New Charts will also be produced when converting an existing chart to a modern datum (to the WGS84 horizontal datum and LAT vertical datum).

Charts superseded by New Editions and New Charts are promulgated by NTMs. Superseded charts are not maintained by NTMs and should not be used for navigation.

How do I obtain Australian Notices to Mariners

If you are want access to Notices to Mariners on a casual basis and know the chart number you are after, you can use our Australian Chart Index for both paper charts and ENC cells to find your chart, then access a cumulative list of Notices for that chart via the view option. This option is recommended if you wish to correct a small number of charts and need to know which notices are applicable to these specific charts.

If you want to automatically receive Notices to Mariners via email for the charts you hold in your portfolio you can register for our eNotices service. Then as Australian Notices to Mariners are published you will be automatically emailed only the Notices to Mariners that affect your portfolio of charts. For more information or to register for the service see the eNotices section of this web site.

Alternatively Australian Notices to Mariners editions are also available from the following sources:

  • The View Australian Notices to Mariners section of this web site.

  • Note:
    Notices to Mariners Editions are available from 1997 to current year.
    Notices to Mariners Blocks, Notes are available from 1999 to current year
    Notices to Mariners Tracings are available from 2001 to current year
  • From Distribution Agents who provide a paper Notices to Mariners service. For details see the Distribution Agents section of this web site.

Why do I need to update my charts and publications for Notices to Mariners?

Notices to Mariners (NtMs) are the means by which all national hydrographic offices provide the latest safety-critical information to mariners.  It is therefore imperative for all mariners to update their charts and nautical publications for NtMs to ensure that they continue to be safe to use.

Types of safety-critical information that may be issued as an NtM or NtM block to update a paper chart or nautical publication include but are not restricted to:

  • Reports of new dangers significant to surface navigation eg shoals, obstructions and wrecks,
  • Changes in general charted depths,
  • Changes in vertical clearances of bridges,
  • Changes in cables and pipelines both overhead and on the sea floor,
  • Significant changes to navigational marks and lights
  • Changes in prohibited/restricted areas, anchorages etc
  • Additions and deletions of conspicuous landmarks
  • Changes to port infrastructure eg changes to wharves, reclaimed areas, available depths, works in progress and new port developments
  • Changes in pilotage areas etc

About Printing Tracings and Blocks

It is important that tracings and blocks are printed at the correct size so that they will ‘fit’ the corresponding chart. To ensure correct fit, mariners should note the following:

  1.  Some printer settings may distort the size of the tracing or block being printed. Tracings and blocks should be printed at 100% size. Any printer setting that implies the size or scale of the image will be changed (such as ‘fit to’, ‘reduce to’, ‘shrink’ or ‘expand’) should not be selected.
  2. Editions of Australian Notices to Mariners are ‘pdf’ files that are best viewed with the latest version of Adobe Acrobat Reader.
  3. When printing blocks and tracings using Adobe Acrobat Reader, ensure that the ‘Page Scaling’ setting is changed to ‘None’.
  4. Blocks published from Notices to Mariners Edition 16/2008 (15 August 2008 onwards) have block dimensions written on them. Mariners can therefore check the printed size of these blocks with a ruler.
  5. The appropriate check of print accuracy is how well the printed block or tracing fits the corresponding chart. For tracings this is a matter of how well the static information and graticule lines drawn on the tracing matches the corresponding underlying chart. For blocks it is a matter of how well the information at the edges of the block match up with the corresponding underlying chart for example, do the contours meet?
  6. Variations in size of up to 1mm can be expected. Mariners should also note that tracings should only be used as a guide when applying Notices to Mariners updates.
  7. Mariners experiencing difficulties with printing blocks and tracings to correct size should contact the AHO Notices to Mariners department.


How do I apply Notices to Mariners to my charts

Please refer to AHP24 - Australian Chart and Publication Maintenance Handbook for detailed information regarding application of Notices to Mariners to your charts.

Are my charts and publications up to date for Notices to Mariners when I purchase them?

AHO Paper Charts: 

If you have purchased your AUS and SLB paper navigational charts from an authorised AHO ‘Correcting Agent’, your charts should be up-to-date for NtMs at the time you purchased them.   However you will need to update them yourself from this point forward until a new edition is released.

If you have purchased your AUS and SLB paper navigational charts from another source such as an AHO authorised ‘Non Correcting Agent’ or a retail outlet of one of our authorised agents, it is unlikely that your charts will be up-to-date. You should therefore update them yourself before you use them and then keep them up-to-date until a new edition is released.

Authorised agents are listed as ‘Correcting Agent’ or ‘Non-correcting Agent’ on our Distribution Agents list.

Nautical Publications

Unless you have purchased a brand new edition or reprint of a nautical publication it is unlikely that it will be up-to-date for Notices to Mariners. You will therefore need to check that your copy contains the latest NtMs and it will be up to you to transpose corrected information onto the pages of your book.

How do I determiNe how up-to-date my PAPER chart is?

  • To determine the update status of your copy of a chart you should conduct the following checks in the following order:
  • Identify the chart number of our chart.The chart number can be found on the top left or bottom right corner of your chart. In the example below the chart number is ‘Aus 821’

  • Identify the edition of your chart.  The edition date can be located at the bottom of a chart.  If a number of edition dates are listed, the edition of your copy is chronologically the most recent date listed.  In the example below, the edition date is ‘17 March 2006’.

  • Check the last NtM to be applied to your chart.The NtMs that have been applied to your chart are listed on the chart’s bottom left corner.  NtMs are numbered from ‘1’ onwards each calendar year and are therefore unique and specific to a particular piece of safety critical information.   The numbers written in the larger text represent the calendar year a NtM was issued.  The numbers written in the smaller text are the Notice numbers.  In the example below, 4 NtMs have been applied to this copy of Aus 821 and the last NtM applied is NtM ‘559’ of the year ‘2007’.

Note that if the NtM numbers are written in black type (like in the example) then the NtMs have most likely been incorporated into the chart base prior to printing your copy.  If the NtM numbers are written in magenta ink or appear hand written, then the NtMs have been applied to the chart by hand correction. 

How do I determine how up-to-date my PAPER chart should be?

  • There are a number of ways you can check whether your paper chart is up-to-date for NtMs. However, one of the simplest ways is to use this website and select the ‘Australia Chart Index’ then select ‘Paper Chart List ’ and scroll down to find the chart that matches your chart number as identified in step 1a above – in our example Aus 821.  Once found click ‘view’. A similar page to the one below will appear. You should then conduct the following checks:

  • Check that your copy is the latest edition.  You should note that there may be very significant differences in information contained on one edition of a chart and the next.  Therefore you should compare the edition date of your chart copy with the edition date listed on the corresponding chart details page.  The dates should be the same.  In our example we have a match - 17 March 2006 – so our copy is the latest edition of the chart.

It is very important that your chart copy is the latest edition as NtMs only apply to the edition that they were issued for.  It would be unsafe to continue to use an out of date edition and extremely foolish to continue to apply NtMs to one.

If the edition date on your chart is chronologically earlier than the edition date listed on the website then your copy is an old edition and should not be used.  If this is the case and you were sold your copy after the edition date shown you should contact your distributor for a replacement.  There is no point progressing to step 2b.


  • Check that your copy is up to date to the latest NtM.  Compare the last listed NtM on your chart copy with the largest number listed against the latest calendar year on the corresponding chart details page.  If your chart is fully up-to-date to the latest fortnightly NtM Edition, these NtM numbers will be the same.  In our example we have a match 559/2007 – so our copy is fully up to date for NtMs.  However, unless you have recently purchased your chart from an AHO authorised Correcting Agent, this is unlikely to be the case and your chart will need updating.

  • Apply any outstanding NtMs.  If your chart copy is the latest edition but the website lists NtMs that have been issued after the last NtM number listed on your chart, you will need to apply all the ‘missing NtMs’ to your chart by hand.  It is important to apply NtMs in numerical order.  For example, if NtMs 559 and 470 were missing from our chart copy we would need to apply these NtMs to our chart in numerical order (eg NtM 470 first). 

Information contained within a NtM can be viewed by selecting the NtM number from the Chart Details page. For example by selecting ‘NtM 559’ as above, a page similar to the one below would be displayed.

Above you can also see the previous correction number, NtM 470/2007, is again referenced as can be seen in square brackets after the chart number. In our example, you would open NtM 470/2007 and apply this first, then return to NtM559/2007 and apply this next.

How do I apply NtMs to my PAPER chart?

For instructions on how to apply Notices to Mariners to update your charts we recommend the use of the Australian Chart and Publications Maintenance Handbook (AHP24) and Admiralty publication ‘Symbols and Abbreviations Used On Admiralty Paper Charts (Chart 5011)’.  These publications are useful for updating charts published by the Australian Hydrographic Service and those published by other countries. Click here for details.

In addition, the AHO publishes Notices to Mariners Tracings for each NtM edition. Tracings are diagrams that provide instruction on how to apply NtMs that require accuracy positioning them.  Click here for details.

However, at the simplistic level, normal practise is to apply the change, detailed in the NtM, to the face of the chart and then record the NtM number as the next number in the ‘Notices to Mariners inclusive to’ list at the bottom left corner of the chart.  If the year has changed since the last NtM was applied then you will need to record the year as well. In our example below, we have applied NtM number 1999 of the year 2008.

It’s very important that you record NtM numbers and the year that the NtM was issued.  If you don’t, record the NtM number, the next time you use the chart you, or another users, will not know that the chart has been updated.   NtM numbers start from ‘1’ each calendar year.  So if you don’t record the year (if the year is different to the last NtM listed) confusion will reign when you next update your chart.