Admiralty chart
Admiralty charts have been produced by UKHO for over 200 years, with the primary aim of saving and protecting lives at sea.
This department of the Admiralty was established under Earl Spencer by an order in council in 1795, consisting of the Hydrographer, Alexander Dalrymple, one assistant and a draughtsman.
[3] Initially charts were produced only for use by the Navy, but in 1821, Thomas Hurd, who had succeeded Dalrymple as Hydrographer in 1808, persuaded the Admiralty to allow sales to the public.
Printing was in black and white, but some charts were hand-coloured, either to emphasise water depth or terrain, or to indicate specific features such as lighthouses.
[10] Chart design gradually simplified over the years, with less detail on land, focusing on features visible to the mariner.
These were successful, and by the outbreak of World War II all chart production used this process, which was faster, and reduced wear and tear on the copper original.
There was also concern about the safety of the original printing plates in the event of air raids, and high quality baryta paper proofs were made as backups.
Llewellyn Styles Dawson was a surveyor particularly noted for his work in China (1865-1870) and a naval assistant in the department for five years (1876-1881).
[4]: 5–6 Thomas Henry Tizard published a chronological list of the officers and vessels conducting British maritime discoveries and surveys until 1900.
[8] A less formal account of British Naval Hydrography in the 19th-Century is given by Steve Ritchie, Hydrographer 1966–1971, in The Admiralty Chart.
[19] A number of major overseas surveys were completed in the years to 1855, a period dominated by Francis Beaufort, Hydrographer from 1829 to 1855.
What Robinson (1962) described as the "Grand Survey of the British Isles" began with the appointment of George Thomas as Head Maritime surveyor.
Thomas and a series of able surveyors including Michael Slater, Henry Otter, Charles Robinson, William Hewett and Frederick Beechey surveyed the coasts of Britain and Ireland over the next 30 years.
Thomas developed techniques for extending triangulation over the shallow waters of the Thames Estuary and the southern part of the North Sea, allowing the exact positions of treacherous sand banks to be determined for the first time.
By 1855, when Beaufort retired, the survey of the coasts of the United Kingdom was complete,[5]: 248 and there were about 2,000 charts in the catalogue, covering all the oceans of the world.
George Nares in HMS Newport traversed the canal in both directions taking soundings and making measurements, and also surveyed the approaches.
As well as increasing productivity, it enabled continuous monitoring along a sounding line, reducing the chance of a hazard being missed.
When navigating over longer distances the difference becomes important, and charts using the gnomonic projection, on which all great circles are shown as straight lines, are used for course planning.
[28] Alongside its paper charts, UKHO produces an expanding range of digital products to fulfil the impending compulsory carriage requirements of ECDIS/ENCs, as issued by the International Maritime Organization (IMO).
This is ensured by UKHO continually assessing hydrographic data for vital safety information, with urgent updates issued via weekly Notices to Mariners (NMs)
