Analysis of naturally etched surface of brass sheathing from a nineteenth-century shipwreck

The Akko Tower Wreck is ently the remains of a 25-m-long merchant brig, dated to the first half of the nineteenth century. During the 2015 underwater excavation, a piece of brass sheet was retrieved from the shipwreck and its surface and bulk were examined by metallurgical analyses. The examinations revealed a unique example of almost two hundred years’ natural etching, which took place in the sea underwater environment. The surface of the sheet was covered with different copper and zinc oxides, which were identified by XRD analysis. Observation of the naturally etched surface with multi-focal light microscopy and SEM-EDS analysis indicated a microstructure of annealed α-brass, similar to that of its bulk. S-OES chemical analysis of the bulk revealed a composition of 65.0 wt% Cu, 34.4 wt% Zn and 0.6 wt% Pb. Based on the thickness of the sheet and its good state of preservation, it is suggested that it was used as sheathing to protect the hull against marine organisms, and to improve the sailing qualities of the ship. The results provide further information about the Akko Tower shipwreck; and expand our knowledge regarding the corrosion processes and preservation of brass during a long burial period in marine environments

Casting techniques of cannonballs from the Akko 1 shipwreck: Archaeometallurgical investigation

Eleven cannonballs were found in the Akko 1 shipwreck; two of them, a 9-pdr and a 24-pdr, were retrieved and studied using archaeometallurgical methods. Findings are reported in the present work. The aim of this research was to study the manufacturing technologies of the two cannonballs, and if possible to determine their date and manufacturing location according to the detailed technological analysis. The examination used optical microscopy, scanning electron microscopy, including energy dispersive spectroscopy, and hardness tests. The results show that the two cannonballs were casted by sand moulds, in two dissimilar processes and were made of different types of cast-iron. The non-uniformity of the 24-pdr cannonball could be the outcome of using a feeder of gray cast-iron in order to complete the casting process and compensating for the shrinkage of the metal. Based on their manufacturing process, it is suggested that the cannonballs were manufactured about the end of the first half of the nineteenth century. Combined with the archaeological and historical background, this supports the possibility that Akko 1 was a naval auxiliary vessel, which was in Akko harbour circa 1840

Under the Mediterranean I, Studies in Maritime Archaeology

International audienc

Detection and mapping of shipwrecks embedded in sea-floor sediments

The paper discusses the detection of shipwrecks embedded in sea-floor sediments using a Chirp sub-bottom profiler. From a methodological-historical perspective it presents four examples of recent chirp recordings of verified shipwrecks embedded in different types of sediment environments, from different geographical and geological areas and from different periods. The effects of shallow water depths, different sediment types, recording speed and different (2D and 3D) sub-bottom profiler systems are briefly discussed. It is concluded that Chirps are well suited for survey purposes, producing high quality 2D profiles of good resolution and satisfactory penetration depth. Furthermore, the equipment is easy to handle from a small boat and allows flexible sailing. This type of 2D data is cheaper and faster to acquire and is easier to interpret and apparently also provides better resolution and detail than present 3D systems. Chirp data are therefore of great value in identifying and outlining shipwrecks hidden in the sea floor in survey situations where larger areas must be covered. The overall conclusion is that there are grounds for optimism with regard to this method of detection of maritime archaeological targets.SCOPUS: ar.jinfo:eu-repo/semantics/publishe