UK Hydrographic Office Visit


Report and photos from Tristan Government UK Representative Chris Carnegy


The UK Hydrographic Office is a world leader in marine mapping, producing the Admiralty charts that guide an overwhelming majority of global commercial shipping. A briefing for Overseas Territory representatives at their impressive new headquarters in Taunton gave a glimpse of the data they hold about the Tristan archipelago – and of an ancient chart of the Tristan ‘top islands’.


The visit on 20th April was hosted by the National Hydrographer, Rear Admiral Rhett Hatcher. It included sessions on the legalities around islands’ Exclusive Economic Zones, the latest mapping technology, and the UKHO’s work to update OT charts (which may in future include some new analysis of Tristan waters). The UKHO helped with the recent designation the Tristan da Cunha ‘Area To Be Avoided’ that aims to keep passing vessels clear of danger.


The 1811 Admiralty Chart of the northern Tristan da Cunha Islands
orientated unconventionally with South at the top and showing the islands of Tristan da Cunha,
Inaccessible and part of Nightingale Island with its satellite islands, then not named.


In his book ‘Tristan da Cunha and the roaring forties’, Alan Crawford attributes the origin
of the chart to a survey made in 1767 by M. Donet of the French corvette L’Heure du Berger.


Crawford confirmed that it was compiled by A Dalrymple according to an Act of Parliament
of March 17th 1781. Dalrymple was official hydrographer of the East India Company
and in 1795 became Hydrographer to the British Admiralty.


The day concluded with a visit to the UKHO archives, and an encounter with a legendary chart showing the relative positions of Tristan, Nightingale and Inaccessible islands. Published by the Admiralty in 1811, it was based on a survey by a visiting ship in 1767.