The Wreck Site, Facilities & Conditions – Artefact Recording – Excavation Seasons 1 & 2 – Excavation Seasons 3 & 4
Excavation of the Batavia Wreck Site (cont...)
4. Artefact Recording
General Recording
The record of the progress of the excavation, wind, weather, sea state, diving-log and other associated matters, were recorded in a daily diary. Archaeological notes were kept on the page opposite the record of the day, together with photographic data, survey information and technical notes. The artefacts were recorded in finds books and were designated an arbitrary prefix number to identify material type, thus:
1. Stone
2. Ceramic
3. Non-ferrous
4. Miscellaneous
5. Coin
6. Timber
8. Ferrous
The location of the find-spot of the object and the date of recovery, together with any other relevant information was also recorded. Where possible, identifiable objects were photographed and drawn on plastic drafting film with Indian ink at a 1:1 scale.
Studying the artefacts immediately at the field station was useful, particularly with ceramic material, as it was then possible to return to the find spot to search for missing pieces.
Underwater Recording
It was difficult to make accurate taped measurements because of the strong surge. Therefore a simple system was adopted consisting of a taut wire base-line run out over the long axis of the site with a sliding right angle frame constructed to run through the base-line. Objects were coordinated by sighting along the arm of the frame at right angles to the wire. By measuring the distances along the wire and along the right angle arm to the object, it was possible to determine its position.
Additionally, a contour map of the wreck site was made by running a series of seven parallel lines three metres apart, along the long axis of the site. Depth measurements were made at 1m intervals along each line with a Bourdon type depth gauge. The results were transferred to the plan of the wreck site, from which contours at 1m intervals were constructed.
Timber Recording
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Each piece of the ship’s structure was tagged in situ. The tagging system used a coded number, with a prefix letter to identify the type of component. Six basic layers were distinguished in the side of the ship and these were coded alphabetically from the top to bottom, corresponding to the inside (top) to the outside (bottom). The numbers differentiated timbers in particular layers. Thus:
A. Knees, decking, deck beams and everything on top of the ceiling
B. Ceiling
B. Thin skin on top of B
C. Frames
D. Inner layer of strakes
D1. Thin skin on top of D
E. Second layer of strakes, lying below or on the outside of D.
F. Sheathing
T. Stern structure.
As each layer of timber was uncovered, it was tagged, photographed, raised and returned to the base camp. Here, each individual piece of timber was given a registration number, identified, and then stored in sea water tanks. During bad weather periods, the timbers were removed from the tanks, drawn, photographed, and then returned to storage.
Drawings of the timbers were made by tracing the surface shape and features onto thin gauge polythene sheeting. Where necessary, drawings were supplemented by photographs. Speed was essential in this process, as there was a danger that the timber might warp or crack with exposure or during transport.
Underwater Photographic Recording
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Three types of photographic recording were carried out on this site: site photomosaic, timber photomosaic, and stereo recording.
Site Photomosaic:
A photomosaic of the whole wreck site was made at the start of the first season, to supplement the site plan. Seven taut parallel lines 1m apart and 46m long were taped with black PVC tape at 1/2m intervals to form a scale and laid along the long axis of the wreck site. Photographs were taken at 1m intervals along each of the lines.
Timber Photomosaic:
As areas of the ship’s structure were uncovered, individual timbers were labeled and photographs were made of all exposed areas of each timber. The surface layer of timber was then removed and the underlying layer was re-tagged where necessary and a second mosaic was made. In this way, a series of photomosaics of the individual layers of the structure were obtained over the entire area of the site.
Stereophotography
was employed to aid in interpreting the photographs of the structure in complex areas of the site. The additional dimension this provided meant that an apparently featureless area of seaweed and concretion, when viewed with stereoscopy, immediately revealed the position of cannon balls under concretion and other three dimensional features.
Photographic Recording on Land
At base camp during the bad weather periods, each individual timber was brought out of the sea water tanks for drawing and photography. Indirect light was the best type of lighting for photographic recording of surface details of the almost black timber. An open-ended shed provided shade from direct sunlight. In the roof of the shed, 2 m above the ground, a Nikon F reflex camera was mounted and levelled with a spirit level. The timbers were wheeled in on a trolley and positioned directly below the camera, using a spirit level to ensure the plane of the timber was uniform over the whole object. With large or long timbers, a series of overlapping photographs were taken by moving the trolley under the camera to make up composite images.
The Wreck Site, Facilities & Conditions – Artefact Recording – Excavation Seasons 1 & 2 – Excavation Seasons 3 & 4
