Wooden Shipwrecks of the Central and Western Gulf of Mexico

Abstract Shipwrecks with wooden hulls are underrepresented in the archaeological record from shallow federal waters of the central and western Gulf of Mexico (defined as less than 600 feet deep), yet they tend to be older and arguably more abundant than shipwrecks with metal hulls. This paper quantifies the extent of bias in favor of metal hulls in the archaeological record; examines its potential causes; discusses factors affecting the preservation and discovery of wooden hulls; and proposes a research strategy that might accelerate discoveries of wood-hulled shipwrecks. Introduction The waters of the central and western Gulf of Mexico have been extensively studied by archaeologists for several decades (Figure 1). This is largely due to the intensity of oil and gas production in the area. The Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) regularly sponsors archaeological studies in addition to reviewing archaeological reports submitted on behalf of oil and gas operators in connection with offshore energy leases. Figure 1 shows locations of roughly 7,000 geo-hazard surveys conducted by the oil and gas industry in the central and western Gulf of Mexico. Each of the smallest colored squares in Figure 1 represents a 3x3-mile mineral lease block. Archaeologists have reviewed geophysical data and prepared archaeological assessment reports for 3,161 lease blocks (those colored blue or purple). Green blocks have been surveyed for geo-hazards but have not been assessed by an archaeologist. Pipeline route surveys are not included in Figure 1. BOEMRE also maintains a GIS database that includes over 3,000 historic reports of vessels lost, over 6,000 Coast Guard hazards to navigation, and over 17,000 net hangs reported by fishing trawlers. As a result of such studies, a great deal is known about the archaeology of this area. The BOEMRE database (2007) contains locations for 195 shipwrecks in the central and western Gulf of Mexico, including 12 wooden shipwrecks (Table 1; 7 shallow and 5 deep) and at least 91 wrecks believed to have metal hulls (74 shallow and 17 deep). Twelve percent of shipwrecks in shallow and deep waters, combined, have wooden hulls. In shallow water the proportion of wooden shipwrecks is 9 percent, and in deep water it is 23 percent. Thirty-one wrecks, all of which are visible on sonar, are confirmed as metal by the BOEMRE database. Another 60 are presumed to be metal from their descriptions or because they have prominent ship-shaped sonar targets that clearly resemble sunken vessels. Wood does not survive exposure in shallow Gulf waters for more than a few years, thus sonar images are unlikely for any except recent wooden hulls in shallow water. Information regarding the other database entries is insufficient to suggest the composition of their hulls. Historic records summarized below indicate that prior to the mid-twentieth century shipwrecks with wooden hulls outnumbered those with metal hulls by 13 to 1. Yet metal hulls in the archaeological record appear to outnumber wooden hulls by about 8 to 1. The discrepancy between historical records and archaeological observations cannot be entirely explained by an abundance of metal shipwrecks over the past 60 years, as the modern (2010) ratio of metal to wooden hulls in the U.S. Merchant Vessel fleet is only 3 to 1. It is clear that shipwrecks with wooden hulls are underrepresented in shallow waters of the central and western Gulf of Mexico. This paper examines the extent and causes of archaeological bias away from wooden hulls; discusses factors affecting the preservation and discovery of wooden hulls; and proposes a research strategy that might accelerate discoveries of wooden shipwrecks. Wooden Versus Metal Shipwrecks from the U.S. Merchant Vessel Fleet Government statistics of losses sustained by U.S. Merchant Vessels suggest that the proportion of wooden to metal hulls in the Gulf of Mexico should be much higher than 9 percent (shallow) or even 23 percent (deep). In fact for the period from 1876 through 1947, it is estimated that 93 percent of all U.S. Merchant Vessels lost worldwide had wooden hulls (Figure 2).