Page 18 - TVH 2000 Anniversary Shipwreck Project

Excavation Alex Hildred Equipment The ability to have a stable platform directly above any portion of the site naturally influenced our excavation strategy. A decision was made in the early planning stages to use airlifts exclusively. We planned to use both (152mm) 6” and (100mm) 4” airlifts, the 6” primarily for the removal of overburden and the 4” for more delicate work. The two larger airlifts were connected to the surface with spoil diverted through a large sieve designed to keep the spoil from each separate (Photo10). This facilitated swift removal of the overburden throughout the tidal cycle, times of slack water were generally reserved for survey both manual and acoustic, photography and photogrammetry. Excavation tools were hands and trowels with paintbrushes used for cleaning as required. Strategy Philosophy The decision on where to position excavation trenches was based on the questions we had about the structure of the vessel formulated during an analysis of previous excavations (Figure 6). Most excavation had taken place around the transom and the junction with the port quarter, following the ribs forming the port side towards the middle of the vessel, but not further south than sector B4A, 6m south of the transom. Most of the excavation trenches had been outboard from the structure, recovering artefacts that had fallen outboard off of the port side either as the vessel sank, or as the higher starboard side collapsed over time. Although recovery of artefacts inboard had occurred, there were no recorded excavations inside the vessel. Although excavation had been undertaken outboard of the stern, there were still outstanding questions about the extent and attitude of the remaining structure. As the assumed sternpost was the most obvious obstruction on the seabed, it seemed sensible to attempt to locate this first, and to explore this structure to ascertain for certain the attitude of the hull to the vertical, and the amount of structure left buried at this point. We also wanted to nominate several key points on the structure that could be used as indicators of erosion. The sternpost is an obvious choice. As an obstruction, it is also likely to suffer from mechanical damage, in fact the quantity of trawl nets in and around it certainly verify this. It was planned from the outset to put a trench across what had been tentatively identified as the sternpost, outboard, then to move inboard in the same area. In this way we could test all the equipment and hone excavation techniques outside the ship where we knew the stratigraphy was largely disturbed and where we expected less coherency in the distribution of finds. We would attempt to answer our structural questions and then move into more delicate undisturbed areas inboard. At the outset we wanted to put a trench right across the stern to try and locate the starboard side. The aims of the first trench, (2000 Trench 1) a slot from the rudder assembly towards the junction with the port side (B1B and B1A on previous surveys), were the following: • To ascertain the amount of stern structure present and buried and the angle at which it rested in the seabed. • To ascertain the integrity of the hull at the stern. • To excavate from the stern of the vessel outwards (WNW to ENE) to define the stratigraphy. • To gather information regarding mechanical, chemical or biological degradation to structure that we know has been exposed or partially exposed since 1981. • To relocate the bench-marks RP1 to the port side of the sternpost and RP2, on the port quarter. It was expected that this would include a lot of re-deposited infill after previous excavations, we wanted to see whether we could identify this. - 16 -