Earliest known Mariner’s Astrolabe research published today to go in Guinness Book of Records
Guinness World Records have independently certified an astrolabe excavated from the wreck site of a Portuguese Armada Ship that was part of Vasco da Gama’s second voyage to India in 1502-1503 as the oldest in the world, and have separately certified a ship’s bell (dated 1498) recovered from the same wreck site also as the oldest in the world.
The scientific process of verifying the disc as an astrolabe by laser imaging is described in a paper published today (17/03/2019) by Mearns and Jason Warnett and Mark Williams of WMG at the University of Warwick in the International Journal of Nautical Archaeology.
The Sodré astrolabe has made it into the Guinness Book of world records is believed to have been made between 1496 and 1501 and is unique in comparison to all other mariner’s astrolabes.
Mariner’s Astrolabes were used for navigating at sea by early explorers, most notably the Portuguese and Spanish.
They are considered to be the rarest and most prized of artefacts to be found on ancient shipwrecks and only 104 examples are known to exist in the world.
They were first used at sea on a Portuguese voyage down the west coast of Africa in 1481. Thereafter, astrolabes were relied on for navigation during the most important explorations of the late 15th century, including those led by Bartolomeu Dias, Christopher Columbus and Vasco da Gama.
It is the only solid disk type astrolabe with a verifiable provenance and the only specimen decorated with a national symbol: the royal coat of arms of Portugal.
As the earliest verifiable mariner’s astrolabe it fills a chronological gap in the development of these iconic instruments and is believed to be a transitional instrument between the classic planispheric astrolabe and the open-wheel type astrolabe that came into use sometime before 1517.
The thin 175 mm diameter disk weighing 344 grams was analysed by a team from WMG who travelled to Muscat, Oman in November 2016 to collect laser scans of a selection of the most important artefacts recovered from the wreck site.
Using a portable 7-axis Nikon laser scanner, capable of collecting over 50,000 points per second at an accuracy of 60 microns, a 3D virtual model of the artefact was created.
Analysis of the results revealed a series of 18 scale marks spaced at uniform intervals along the limb of the disk.
Further analysis by WMG engineers showed that the spacing of the scale marks was equivalent to 5-degree intervals. This was critical evidence that allowed independent experts at Texas A&M University to include the disk in their global inventory as the earliest known mariner’s astrolabe discovered to date.
Prof Mark Williams from WMG, University of Warwick comments:
“Using this 3D scanning technology has enabled us to confirm the identity of the earliest known astrolabe, from this historians and scientists can determine more about history and how ships navigated.
Technology like this betters our understanding of how the disc would have worked back in the 15th century. Using technology normally applied within engineering projects to help shed insight into such a valuable artefact was a real privilege”
David Mearns of Blue Water Recoveries Ltd comments:
“Without the laser scanning work performed by WMG we would never have known that the scale marks, which were invisible to the naked eye, existed. Their analysis proved beyond doubt that the disk was a mariner’s astrolabe. This has allowed us to confidently place the Sodré astrolabe in its correct chronological position and propose it to be an important transitional instrument.”
WMG is a world leading research and education group and an academic department of the University of Warwick, established by Professor Lord Kumar Bhattacharyya in 1980 in order to reinvigorate UK manufacturing through the application of cutting edge research and effective knowledge transfer.
WMG has pioneered an international model for working with industry, commerce and public sectors and holds a unique position between academia and industry. The Group’s strength is to provide companies with the opportunity to gain a competitive edge by understanding a company’s strategy and working in partnership with them to create, through multidisciplinary research, ground-breaking products, processes and services.
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About David L. Mearns
David L. Mearns is one of the world’s most experienced deep sea search and recovery experts. He has led the research and discovery of twenty-five major shipwrecks around the world and is best known for locating the wrecks of HMS Hood in 2001, the British bulk carrier Derbyshire in 1994, and the cargo ship Lucona sunk by a time bomb as part of an Austrian insurance fraud scheme. He was awarded an Honorary Order of Australia Medal for locating the wrecks of HMAS Sydney in 2008 and AHS Centaur in 2009. In 2015 he was a member of Paul Allen’s team that successfully located the wreck of the Japanese super battleship MUSASHI and recovered the bell of HMS Hood on behalf of the UK Ministry of Defence. Most recently David led the privately funded search that located the Piper Malibu airplane carrying the Cardiff City footballer Emiliano Sala and piloted by David Ibbotson that crashed in the English Channel off the coast of Guernsey. For more information visit http://bluewater.
· A gunmetal disc excavated from the wreck site of a Portuguese Armada Ship identified as a mariner’s astrolabe – and the earliest known example – by engineers at WMG, University of Warwick is to be published in the The International Journal of Nautical Archaeology
· The astrolabe was discovered by David L. Mearns of Blue Water Recoveries Ltd, who directed the three-year archaeological project in collaboration with Oman’s Ministry of Heritage and Culture
· It has been named the Sodré astrolabe after the commander of the ship in which it was found: Vicente Sodré was the maternal uncle of Vasco da Gama and died when his ship, the Esmeralda, wrecked on the remote Omani Island of Al Hallaniyah in 1503
· It will be listed in the Guinness Book of World Records as the oldest mariner’s astrolabe from as early as 1496
Press release from the University of Warwick