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19 August 2015

Identifying areas of possible risk with the ADMIRALTY Information Overlay

The ADMIRALTY Information Overlay (AIO), which is included within the ADMIRALTY Vector Chart Service, is designed to help you identify areas of possible uncertainty and risk at the crucial passage planning stage. Displayed as a digital data set over charts, the overlay contains all Temporary & Preliminary Notices to Mariners (T&P NMs) and highlights navigationally significant differences between ENCs and ADMIRALTY paper charts.​

​​In our latest blog, we take a look at how this functionality works within ECDIS and offer guidance on interpreting any T&P NMs and EP NMs that are displayed. If you would like to learn about using AIO within e-Navigator Planning Station, please click here.​​


How to use the ADMIRALTY Information Overlay

When used on compatible ECDIS, AIO can be switched on and off without changing the underlying chart.

As the user zooms in or out, the ECDIS will automatically select charts of a suitable scale and the Overlay features relevant to that selected chart. For example, a Temporary NM that applies only to a large scale chart will not be displayed when smaller scale charts of the same area are being used.

T&P NMs - All ADMIRALTY T&P NMs that are in force are included in the Overlay. Each NM is displayed as a simple red polygon (usually rectangular) with red hatched fill which indicates the area affected by the NM. Each NM carries the same NM number that is used in the ADMIRALTY Notices to Mariners Bulletin.​

The full text of the NM is included as an associated text file which can be displayed by selecting the ‘Temporary Notice to Mariners’ or ‘Preliminary Notice to Mariners’ feature in the ECDIS Pick Report. Any associated diagrams can also be viewed through the Pick Report.

EP NMs - ENC P (EP) NMs contain additional information that is specific to ENCs and cannot be published as a standard ADMIRALTY T&P NM. These NMs are displayed in the same way as T&P NMs, as a simple red polygon (usually rectangular) with red hatched fill which indicates the area affected by the NM. Each NM is allocated a unique EP NM number.​

The full text of the NM can be viewed in the ECDIS Pick Report against the Information attribute. Where additional information is needed to explain the NM an associated picture file displays an image showing the ENC superimposed over the current paper chart information.​

Compatible ECDIS and installation – You can find an up to date list of ECDIS that are compatible with AIO here. The ADMIRALTY YouTube Channel also contains a number of ECDIS specific installation Films that can guide you through installing and updating AIO. These can be accessed here.​