Hydrodynamics related to shipwreck taphonomy

When a shipwreck and objects in the associated debris field land on the seabed, they continue to be acted on by currents and benthic storms that can result in changes to the position, orientations and dispersion. In shallower waters, ocean storm waves and long period swells can cause strong oscillatory water motions to act on the objects. This paper describes a number of cases where the underwater archeological record shows evidence of these changes, and shows how such cases may be modeled using modern COTS software. The technical approach described in this paper shows how the different specialties of naval architecture, oceanography, ocean engineering, sediment transport, hydrodynamics and underwater archaeology can be usefully combined under the umbrella specialty of marine forensics. The phenomenologies associated with freefall in the water column, bottom impact, and then the impact of various post deposition events and processes are modeled for several historic wrecks and the process and results are illustrated. The differential action of storm waves and how to calculate their frequency of occurrence at a specific depth will be described. The sediment transport like action that can re-suspend objects and or tumble them across the seabed will be described and modeled for typical objects. The action of strong oscillating water motions can expedite a wreck's breakup. Scour and erosion corrosion at the water-to-sediment interface have been implicated in specific damage to some historic wrecks. Lastly, the implications to modern search and rescue and to the research of historic wrecks will be discussed.