This unidentified vessel is known as the "Portland Stone Wreck" and is most likely the remains of a sailing barge or barge-like vessel that sank in the second half of the 19th century. Little of the vessel is visible above the seabed, however the lower sections of the hull are likely to be preserved under the cargo of Portland stone, which is stacked to a height of four metres above the seabed.
 
From the available evidence, the "Portland Stone Wreck" was a carvel built, single masted sailing vessel with a fairly flat bottom, approximately 15-16m long and 5.5m wide. The wreck lies in 7.7m of water (CD), east of Selsey Bill in an area called "The Park".
Multibeam sonar image in 3DIn August 2002 Wessex Archaeology surveyed the site using a number of geophysical methods, including sidescan sonar, magnetometer and multibeam sonar. Several dive assessments were also carried out on the site, recording the visible remains of the wreck and noting their condition.
 
In June 2003, the site was revisited for further geophysical surveying, which included multibeam sonar, sub-bottom profiler and magnetometer. There was also ten dives to the site during the fieldwork, and involved completing a plan of the wreck site using offset and triangulation measurements, sketches and dimensions of vessel features together with underwater photography and video footage (which can be viewed by clicking the red spots on the multibeam image here).
 
Comparison of the geophysical and dive data from both years showed that the site was not deteriorating markedly and that no major changes were evident.
 
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