09 December 2020

In May 2020, we announced, after gathering a considerable amount of user feedback, that the latest version (v4.1) of the ADMIRALTY Celestial Navigation and Astronomical Products NavPac and Compact Data will be digital-only.

Released to the market in May 2020, the digital-only ADMIRALTY NavPac and Compact Data v4.1 also comes with extended data coverage for 2021 to 2025, along with new, environmentally friendly packaging.

Alongside the new and improved version of ADMIRALTY NavPac and Compact Data, we also announced that the previous versions – v3.4 and v4.0 - will be gradually phased out before being fully retired on 31 December 2020.

What to do next


With the retirement of v3.4 and v4.0 taking place at the end of 2020, all users who are still using these versions will need to migrate to v4.1 by 31 December 2020.

From 1 January 2021, v3.4 and 4.0 will go out of service and will lose all functionality. Consequently, users will be unable to make celestial navigation calculations for any dates beyond this point as well as no longer receiving any customer or technical support from the UK Hydrographic Office or Her Majesty's Nautical Almanac Office team.

To support migration to the newest version 4.1, users are encouraged to speak to their ADMIRALTY Distributor in advance of the final retirement date on 31 December 2020.


"Between May and December 2020, we have been gradually phasing out the previous versions of ADMIRALTY NavPac and Compact Data to make way for the new, customer-led, digital-only v4.1. To ensure users do not lose any functionality of their celestial navigation tools from 31 December 2020, we recommend they immediately speak to their distributor and make plans to migrate to the new version."

Tamsin Hodge
Job title
Product Manager, UKHO

What is ADMIRALTY NavPac and Compact Data and what is it used for?


ADMIRALTY NavPac and Compact Data provides navigators and astronomers with simple and efficient methods for calculating the position of the sun, moon, navigational planets and stars with the aid of a personal computer running Microsoft Windows 8 and 10.

It allows navigators to compute their position at sea using traditional celestial navigation techniques combined with modern technology.

ADMIRALTY NavPac and Compact Data is used world-wide by the Royal Navy and other navies around the world as well as commercial navigators who use it to provide independent and reliable verification to their on-board Global Navigation Satellite System (GNSS).

If you have any questions regarding this product or the newest version, please get in touch with our customer service team at customerservices@ukho.gov.uk

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