Considerations in Conserving Wooden Ships
Archaeological excavations worldwide reveal wooden ships, usually in waterlogged conditions where a decision must be made whether to begin conservation treatments, leave in situ, or do nothing to protect the vessel. Many aspects must be considered and this usually begins with whether the find is located on public or private lands, and where in the world the archaeological site is located. Depending on the country, laws lay out the requirements for the management of shipwrecks. For example, in the United States the Abandoned Shipwreck Act of 1987 delineates government ownership and the management of most abandoned shipwrecks, while other countries have similar statutes. In fact, the UNESCO Convention on the Protection of Underwater Cultural Heritage is a treaty that was adopted in 2001 by 45 countries and was designed to protect submerged cultural objects and sites older than 100 years. In any case, each decision carries with it the positive aspects as well as negative implications.
Most wooden shipwrecks from archaeological environments are not fully excavated, conserved, and exhibited, due to the high number found, the high cost, and ongoing time requirements. The options to leave wooden shipwrecks in situ or to reinter them into their original location or another suitable environment have become favorable amongst some archaeologists and conservators. Björdal and Nilsson (2008) conducted a study in Marstrand harbor, Sweden to see how wood samples of sound oak, pine and birch decomposed above and within marine sediment. Their findings suggest that reburial of wooden shipwrecks in marine sediments is a viable option for long-term preservation of these vessels. Although there is a considerable amount of time and money required to conduct an archaeological project where the result is to leave a shipwreck in situ or to rebury it, these resources are significantly less than what is required to excavate and apply conservation treatments to them. The few wooden shipwrecks that are deemed significant enough to conserve require a lot of time planning, excavating, retrieving, and ongoing upkeep to ensure their long-term preservation. Positive outcomes related to this planning includes such as putting the find into the place and time where it originated, adding to the body of knowledge in disciplines like history, anthropology, archaeology, and other fields of study; and increasing the general public’s awareness of and involvement in their cultural heritage which sometimes leads to additional funding for further research and conservation projects. The positive outweighs the time commitment and financial impact in conserving some archaeological conservation projects, one example being the Mary Rose.
The Mary Rose is a 16th century wooden ship owned by Henry VIII and sunk in 1545. It was extracted in 1982 and continues to undergo conservation work; the Mary Rose Museum opened May 31, 2013 where the public can observe the final stages of conservation through viewing ports. Not only do visitors get to tour the museum and learn about some of 16th century in England, they have the opportunity to observe some conservation techniques in progress! In addition to public support, the raising of this vessel has contributed to researchers’ understanding of underwater archaeology and conservation techniques.
The decision whether to excavate a wooden shipwreck requires a commitment to following legislation governing archaeological, conservation, and preservation activities and there is a substantial amount of planning, resources, time, and money needed to engage in these processes. Conservators are expected to adhere to ethical guidelines that are the framework for ensuring they demonstrate the proper treatment of the objects they conserve. Sometimes a find such as the Mary Rose is deemed to be culturally and historically significant and the positive outcomes of that find outweigh the extensive resources required to save it. Not all wooden shipwrecks discovered can be excavated and the alternative options of reburial or leaving them in situ are conducted in the hopes that these vessels survive long-term until better methods for conservation and preservation are developed. In any case where an abandoned shipwreck is discovered, decisions must be carefully made and there are both negative and positive implications that result from those decisions.
American Institute for Conservation of Historic and Artistic Work (AIC) 2003 Defining the Conservator: Essential Competencies. Pp. 3-17.
Björdal, Charlotte Gjelstrup and Thomas Nilsson 2008 Reburial of shipwrecks in marine sediments: a long-term study on wood degradation. Journal of Archaeological Science 35:862-872.
National Parks Service 2014 Archaeology Program. Abandoned Shipwreck Act (ASA). http://www.nps.gov/archeology/tools/laws/ASA.htm. Retrieved on March 18, 2014.
National Parks Service N.d. Federal Historic Preservation Laws. Abandoned Shipwreck Act of 1987. http://www.cr.nps.gov/local-law/FHPL_AbndShipwreck.pdf. Retrieved on March 18, 2014.
The Mary Rose website. http://www.maryrose.org/. Retrieved on March 18, 2014.
United Nations Educational, Scientific and Cultural Organization (UNESCO) 2001 Convention on the Protection of the Underwater Cultural Heritage. http://unesdoc.unesco.org/images/0012/001260/126065e.pdf. Retrieved on March 18, 2014.
United Nations Educational, Scientific and Cultural Organization (UNESCO) 2001 Convention on the Protection of the Underwater Cultural Heritage. Paris, 2 November 2001. http://www.unesco.org/eri/la/convention.asp?KO=13520&language=E&order=alpha Retrieved on March 18, 2014.