Seals, sharks and shipwrecks
Team members swimming past the bow section of the Lady Darling. Image: ANMM.
Kieran Hosty, Manager of Maritime Archaeology, Seals, sharks and shipwrecks: 3D mapping the Lady Darling shipwreck, Australian National Maritime Museum Blog, 23 August 2016
New South Wales hosts a wide variety of historic shipwreck sites. These range from large, fully exposed and intact hulls to smaller, largely disarticulated, dispersed, and buried structural components and artefacts. The environments in which these sites exist also differ significantly in terms of seabed composition, water depth and water clarity.
Many historic shipwrecks in New South Wales waters are located at depths near or in excess of 20 metres (66 feet) and are characterised by moderate-to-low visibility conditions. These attributes in turn often negatively influence working conditions, particularly the amount of time available to execute an adequately comprehensive documentation program.
As Dr James Hunter recently discussed in his blog Meanderings in the Murk: Diving on the wreck of the Centennial, the use of 3D mapping software such as AgiSoft Photoscan and small compact underwater digital cameras such as the GoPro to document and analyse submerged archaeological sites is an emerging field of research in maritime archaeology.
Although digital photogrammetry has rapidly evolved into a relatively inexpensive and efficient means of documenting submerged shipwreck sites, it is still fraught with issues and in-water survey methods still need significant refinement in order to produce the most time and cost efficient results. In an effort to test the efficiency of these methods as a mapping tool maritime archaeologists at the museum’s Maritime Archaeology Research Centre (MARC) and the Silentworld Foundation have selected five shipwrecks in New South Wales waters with diverse site and environmental profiles.
These include the composite-hulled sailing ship Centurion (1887), the paddle steamer Herald (1884), the screw steamship Royal Shepherd (1890), the iron-hulled steamship Centennial (1889) and the iron-hulled steamship SS Lady Darling, which was wrecked south of Montague Island off Narooma, New South Wales, in 1880.