Seaport Shipwreck

Until it was filled beginning in 1885, the site of the Seaport Shipwreck was part of the expansive South Boston Flats, a tidal mudflat that would have been dry at low tide and submerged at high tide.  Much of the land that today makes up the Seaport district of South Boston was filled in the 19th century.  The Seaport Shipwreck was found under 20 feet of fill resting directly on clay in what used to be the harbor's seabed.

During initial construction work at the site, dozens of massive H-piles (steel beams) were driven into the fill prior to it being excavated. This resulted in two piles unknowingly impacting the shipwreck well before excavations reached it.  Excavation crews removing the fill with heavy machinery found the wooden hull of the ship and stopped excavations.

Once enough fill had been removed that the hull was fully exposed, it was clear that an important archeological discovery had been made. The developer, Skanska, willingly stopped work in the area and called in professional archeologists to document the site.

The remains of the Seaport Shipwreck included a significant portion of the lowest part of the ship's hull, measuring 47 feet long by 15 feet wide.  The stern or rear of the ship was missing, but it is likely that the ship was between 60 and 80 feet long when built.

The archaeological team documented several hull components including a keel, keelson (a timber beam that runs along the interior center of the hull), three plank types (floor, ceiling, and hull), one knee timber (interior brace), two mast steps (hole in the keel and planks for the mast), and numerous futtocks (ribs).  

Plan drawing of Seaport Shipwreck remains. (Image Credit: Public Archaeology Laboratory, Inc.)

Archaeologists documenting the site found dozens of partially burned wooden casks or barrels filled with lime.  These barrels were placed on their side parallel to the keel and stacked so tightly that there were almost no spaces between each barrel.  Historic records of a similar-sized lime schooner was documented to contain over 1,200 lime barrels, and it is likely that the Seaport Shipwreck also contained a similar cargo.

Each wooden barrel measured 1.5 x 2.5 feet in size. They were made from several staves and held together by natural birch hoops.  They were remarkably well preserved in the wet conditions, with the exception of their burned portions, which had been lost while the ship was still underwater.  A barrel lid was found in the hull with a partial stenciled label "ROCKLA" indicating that the ship and its cargo originated from Rockland, Maine, the leading lime producer in America during the mid- to late-19th century.

Lime would have been an important component in mortar, which was in high demand in Boston for the booming Financial District, Back Bay, Beacon Hill, and South End neighborhoods.

Lower portions of partially burned lime barrels. One barrel excavated to show wood staves. (Image credit: Public Archaeology Laboratory, Inc. )

It is likely that the lime cargo was the source of both the fire and the reason why the boat sank. When lime gets wet, it heats up in an exothermic reaction.  In spite of it being dangerous, shipping lime via boat was still the most cost effective method.

If water managed to leak into the hull, the casks of lime would expand and heat up eventually catching fire, and burning lime schooners were frequently noted in local Boston papers in the 19th century.  It is highly likely that the cargo of the Seaport Shipwreck got wet, caught fire, and led to the burning and sinking of the ship.  The stern (rear) of the ship had burned completely and the barrels of lime were all partially burned.    

The position of the ship found with the bow pointing northeast indicates that the ship was towed to the South Boston flats and deliberately left there, likely as the ship was on fire. It was the safest place for the uncontrollable fire to burn out without catching other ships, wharves, or buildings on fire.  

With the fork not being invented until 1869 and the filling of the land in 1885, we can confidently date the sinking of the Seaport Shipwreck to sometime between 1869 and 1885.  The name of the ship is still unknown and archaeologists are actively pursuing several research leads into the various lime ships from Rockland that meet the description of the Seaport Shipwreck that are documented in historic sources as having sunk in Boston Harbor between 1869 and 1885.

The shipwreck was removed by Skanska in several large fragments after thorough archaeological documentation in order to continue work on the 121 Seaport Blvd. building.  It was stored on flatbed trucks for several months during which archaeologists had the opportunity to continue documentation of the ship's hull and construction.  The shipwreck was part of the privately-owned property of Skanska. As the timbers and overall boat were in a fragmentary state, and as complete conservation and restoration were not feasible (only the lowest portion of a very large ship hull was found intact), creative alternative uses of the ship's timber were sought.