Page 237 - Manual for Activities directed at the Underwater Cultural Heritage

offshore technology has the dual effect of reducing rental, shipment and purchase rates with technology becoming more versatile for some of the tasks related to archaeological documentation.
In choosing efficient documentation techniques, one should be prepared to combine different systems. It is quite clear that simple offset measurements and sketches are the most efficient in limited excavation trenches. In setting up a grid for measurements, a Direct Survey Method including computer- processing of simply measured direct distances is to be preferred. There are several simple and readily available computer programmes that can process such data with the help of non-parametric statistics. In documenting complex structures, long periods of underwater work can be avoided by combining simple triangulation with voice-recording of the measurements and processing in the dry. Direct distances, measured with tape measures, should not as a rule exceed 20 or 30 meters, especially not if visibility is low. Therefore, if measurements need to be taken over larger distances, the tracking devices of the offshore industry might be an efficient answer, especially if their deployment can be focused and concentrated on a few days. For shallow sites, GPS– positioning with the antenna on a long pole may
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© National Museum of Underwater Archaeology. ARQUA. A Remotely Operated Vehicle (ROV), Spain.
The ROV is part of the remote- sensing equipment that can be employed to help uncover hidden archaeological sites and artefacts. The term ROV stands for Remotely Operated Vehicle
and designates an underwater robot that is used in underwater environments too dangerous or deep for human divers to operate within.This makes them a useful tool in the field of Maritime Archaeology when surveying wrecks and other underwater archaeological sites.
The ROV can vary in size from small vehicles with TVs for simple observation up to complex
work systems, which can have several manipulators,TVs, video cameras, robotic grips, tools and other equipment.The vehicle is powered and operated from the surface through an umbilical line that runs out the back of the robot. Depending on the size of the ROV the working depth may reach a maximum of 7,000 m. There are many examples of ROVs being used in Maritime Archaeology.The Mary Rose fieldwork in 2003 included using an excavation ROV to remove the top layer of silt that had covered the wreck leaving the delicate excavation to be done by divers with airlifts.
Documentation