Archaeological site evaluation in the North Sea location Borssele Windfarm III/IV

ADC Maritiem has realized an archaeological site evaluation on a shipwreck (site D06) and investigate two cannons (site E04 and H04). The three sites are located in the windfarm area Borssele III/IV near the Southern border of the Dutch Exclusive Economic Zone and approximately 500 meters from the Belgian EEZ (figure 1). The archaeological value of the sites needed to be determined because they were situated within within a perimeter of 100 meter of the planned wind turbines and cable corridors. Dutch policy states that (possible) archaeological sites in the EEZ of the North Sea need to be left undisturbed with a buffer of 100 meters. The operation had to be executed in accordance with the Dutch quality standard KNA Waterbodems 4.1. and within limits of operational restraints and safety concerns. Usually this kind of archaeological research is executed by underwater archaeologists and divers combining archaeological field methods with geophysical data. For two reasons diving was not feasable for this project. In the first place this zone of the North Sea is unfaforable for diving operations due to strong currents, relatively large sand dunes and water depth. Secondly the safety policy of Blauwwind states that no diving should be executed within their projects. For these reasons the project is done with survey equipment and a Remotely Operated Vehicle (ROV) under supervision of maritime archaeologists of ADC. This ROV was employed for an UXO campaign in the Borssele III / IV area and archaeological fieldwork was integrated in the planning. The project is executed from the survey ship Noordhoek Pathfinder (NHP). The operation is managed by Van Oord Offshore. The ship is equiped with a range of survey tools. Basic equipment is the Triton XLX workclass ROV system, multibeam sonar, subbottom profiler, side scan sonar, magnetometer and crane or grab capable of lifting a 5 ton load or more after rewiring. A BODAC owned airlift system is also installed on board to assist the research. Last but not last a moonpool is built into the ship construction. The ship is quite flexible and can be reroled to accept a range of jobs by switching containers on the quarterdeck. The cannons were successfully recovered and brought ashore for the purpose of conservation. Cannon site E04 was inspected afterwards conform planning to check for any possible wreckage. Visual inspection as well as post survey with an electromagnetic detector and a multibeam sonar did not reveal the presence of any possible wreckage material underlying the cannon position. The results of archaeological investigation of these cannons will be reported separately. The wreck in D06 was examined by preparing a trial trench and by documenting it with the camera’s installed in the ROV. Because of the constant backfill the trial trench in site D06 could not be fully uncovered, resulting in a patchy dataset of the wreck that was positioned between one and two meter below the surface of the seabed. However a coherent image emerged after analysis. The original ship must have been around 5 meters wide and 15-20 meters long. It is assessed to have the characteristics of a coastal vessel, most likely a small freighter. The ship construction elements do not match the proportion of an ocean going vessel or inland vessel. From the construction details could be inferred that the wreck is dated in the nineteenth or early twentieth century. However, this is not corroborated by dendrochronology analysis of the recovered timber elements from wreck D06. Wreck D06 is party disintegrated in the tidal dynamics of the North Sea. Only one half of the ship’s bottom remains and one side of the hull, probably port side. The timbers were mainly joint with iron bolts consumed in the process of corrosion. As a result the construction elements lost their interconnection for most part, but are still in original structural position. Vulnerable parts of the ship structure however like the turn of the bilge and the top side of the hull show a substantial amount of disorder. Examination of the timbers retrieved from the site reveal that the conservation of the timbering is poor, as stone borers and wood worms damaged the wood structure. Additionally the timbers are moderately to severely eroded by the prevailing currents. No artifacts related to cargo, inventory or personal possessions were encountered during fieldwork.