3D documentation of shipwrecks embedded in sea-floor sediments

Abstract

3D documentation of shipwrecks embedded in sea-floor sediments, and not visible above it, is potentially an important aspect of maritime archaeological survey and management. Known shipwrecks embedded in the sea floor have been registered in 3D as part of 3D chirp-system research, which focussed on these specific features. But this method is expensive, time-consuming and complicated to handle. This presentation will discuss a development in the direction of a faster, cheaper and less complicated method, consisting of Chirp acquisition in a rather dense 2D grid that need not be regular. The presentation is based on the results of ongoing survey work in the Akko Harbour area, off the Carmel Coast, Israel. The results show that the hull of the detected shipwreck, and its shape, can be nicely identified and that sedimentary units bounding the hull can be outlined and interpreted. Based on an interpretation of the outline of the curved hull, the depth was measured, and a 3D image of the shipwreck produced. Samples of the subsea floor have been obtained from the area, and the one located with the extent of the mapped shipwreck contained wood fragments. The presentation shows that 2D surveying is an alternative to 3D surveying, as it is cheaper, faster, less complicated to operate, less sensitive to weather conditions and can produce good results.