AUSTRALIAN NATIONAL MARITIME MUSEUM 23 and PS Herald NEW TECHNOLOGIES HELP TO RECORD OLD WRECKS 01 Lady D arling Australian waters are the final home of thousands of shipwrecks, some of them in depths that make survey and recording difficult. Maritime Archaeology Manager Kieran Hosty profiles two 19th-century shipwreck sites and explains how 3D mapping software and compact underwater digital cameras are helping to investigate them. AUSTRALIA HOSTS SOME 11,000 shipwrecks – or roughly one shipwreck for every 3.3 kilometres of coastline. 1 They range from large, fully exposed and intact iron and steel hulls to smaller components and artefacts. The environments in which these sites exist also differ significantly in terms of water temperature, depth and clarity and seabed composition. In New South Wales many shipwrecks are located at depths of 20 metres (66 feet) or more, and where visibility is moderate to low. These factors create challenging working conditions, particularly in the amount of time available on the sea floor to execute an adequate and accurate archaeological survey. An emerging field of research in maritime archaeology is the use of 3D mapping software and small compact underwater digital cameras, such as the GoPro, to record and analyse submerged archaeological sites. 2 Although digital photogrammetry has rapidly evolved into a relatively inexpensive and efficient way to document submerged shipwreck sites, it is still fraught with issues, and in-water survey methods need significant refinement to produce the best results. To test the efficiency of these methods as a mapping tool, maritime archaeologists from the museum’s Maritime Archaeology Research Centre (MARC) and the Silentworld Foundation are currently testing a variety of photographic survey techniques on selected shipwreck sites in New South Wales waters that have diverse site and environmental profiles. Two of these sites are the paddle-steamer Herald (1884) and the iron-hulled screw- steamer Lady Darling (1880).