The Wreck Site, Facilities & Conditions – Artefact Recording – Excavation Seasons 1 & 2 – Excavation Seasons 3 & 4
Excavation of the Batavia Wreck Site (cont...)
5. Excavation
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The First Season
The prevailing direction of the swell and surge is along the axis of the site, driving loose material north towards the reef. Before the excavation started, the surface of the site was loosely concreted together with coraline algae to form a crust. Once this crust was broken there was a tendency for the loose material below to be scoured out during storms. Thus the excavation had to be carefully planned to take this into consideration. The stern area was selected as the most obvious starting point, particularly as this was the easiest area to work; the bow area was more turbulent and less often suitable for diving. As the complex of anchors and cannon 10, 11 and 12, in the middle of the site formed a barrier to scouring, it was decided that this would be the northern-most limit of excavation.
Digging a trench on this site was out of the question, since any resemblances to trench walls were rapidly scoured out. It proved most feasible to clear an area systematically, gradually lowering the level by removing the coral lumps and building blocks in the area. As the cleaning operations progressed westwards across the site, the number and quality of the artefacts increased, and several complete stoneware jugs were found around cannon 5. Cannon 5 was removed from on top of the timber, which then showed the structure sloped downhill towards the aft area of the wreck site.
At this point, because of the danger of storms destroying the uncovered timbers, it was decided to dismantle the structure and raise it. The ribs were removed and raised in the lifting tray, after thirty had been tagged and recorded. The strakes were then tagged and photographed. It was found that the outer planking consisted of two layers of strakes, with a further outer layer of thin pine sheathing.
Towards the end of the first season, the area around cannon 1 and 2 was cleared of coral and cannon 3 was raised. The last of the timber was recorded and raised. At this point, 5.5m of timber had been recovered. The rest of the timber was covered with plastic sheeting and several hundred bags of coral, and the excavation was wound up for the winter.
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The Second Season
The first phase of this season was to clear the concretion overlying the timbers. This proved to be extremely difficult, because the concretion contained a large number of iron cannon balls, and as they were cleared further aft, the concretion became thicker. From a series of experiments it was found that the use of small explosive charges (circ. 10 grams) was the most satisfactory technique. Following each charge, the loose cannon-balls were excavated and the broken concretion spoil was airlifted off the site. Many delicate iron artefacts were recovered from this concretion, including bar shot and iron spoons. The ceiling planking was sawn through, and raised. The ribs were then removed, and finally the outer strakes were cut through with the chain saw and raised.
The excavation then proceeded further aft, and cannon 1 and 2 were raised. Once these were clear, five large lodging knees were uncovered running at a slight angle to the strakes. The cannon ball concretion lay over and in between these knees, which made extraction difficult. The western-most knee and thus the highest on the side of the ship, lay directly under cannon 2. The cannon ball concretion started east of the next knee, as it was assumed that this was some sort of stern shot locker. Complex decking in this area was noted, presumably the floor of the gun deck. The cannon balls had therefore spilled across the side of the ship when it rolled over on its port side. The deck acted as a barrier, preventing the cannon balls rolling further west.
Progress during this season was very slow, mainly due to the enormous quantity of coral and concretion that had to be cleared in the stern section. A systematic programme of collecting pottery and bricks on the inside reef site was started and quite a large collection of mainly stoneware was made from this area. This work was carried out during times when it was not possible to dive on the main site.
The Wreck Site, Facilities & Conditions – Artefact Recording – Excavation Seasons 1 & 2 – Excavation Seasons 3 & 4
