Page 20 - TVH 2000 Anniversary Shipwreck Project

width of Terschelling). We moved the vessel, thereby moving the cage and cargo basket, when we wanted to extend the trenches. The acoustic beacon was positioned on the dive cage unless in use by the diver, therefore the position of the cage could be computed for each dive. The position of the cargo basket and the line between the two could be plotted. The acoustic pole was used to plot in control points, artefacts and the edges of the trenches. The airlift was tethered to the cargo basket with a 5m arc of excavation available. Figure 7: Vessel Positions - 18 -