Page 287 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

266 Maritime Archaeology: A Technical Handbook, Second Edition
Figure 9.18 Using a thermal lance (oxy-cutting equipment) to separate the engine from the boiler on the steamship Xantho. (Courtesy of Jon Carpenter, Department of Materials Con- servation, Western Australian Maritime Museum.)
point away from an artifact. Never force the point down between objects because, as the point is driven in, it will tend to produce an expansion and thus a crushing effect. A lot of skill and patience is required to extract del- icate objects from a concretion, and at times this can present a consider- able challenge to the excavator.
Where it is necessary to lever concretions from the seabed, a crowbar can be used with caution. In some cases the concretion may be firmly attached so that it is beyond the power of the excavator and the crowbar to free it. In such cases, it may be possible to utilize a small car jack or a hydraulic ram (Figure 9.19).
D. CHAINSAW
During the excavation of the Batavia (Baker and Green, 1976; Green, 1975), large ship timbers were uncovered. The timbers were too long to recover in one piece, so they had to be cut into sections. Because the wood was so hard, the only effective way of cutting the timbers was with a pneu- matic chainsaw (Figure 9.20). This proved to be extremely efficient and quick and made the operation, which would otherwise have been virtually impossible, an easy task.