Secrets of WTC Shipwreck Sleuthed Out
From Christina Reed - Discovery News
Unraveling the mystery surrounding the shipwreck found last year during excavations of the World Trade Center site has resulted in several facts as well as theories.
The 18th century vessel, likely a single-masted sloop, measured approximately 50 feet long, and had a shallow, double-ended draft aided by a small, tapered keel built of squared-off hickory that that ran from stem-to-stern.
The hull was built from Philadelphia oak trees -- one of which had lived for at least 111 years and was still growing in 1773, its youngest sapwood preserved in one of the boat's timbers.
Maritime historian Norman Brouwer had suggested that the unusually crafted sailboat was from a small rural shipyard and the trees for its timber from the same forest. "The data we see suggest something very similar," says Neil Pederson of the Lamont-Doherty Earth Observatory's Tree Ring Lab in Palisades, NY.
"It's an interesting intersection in experts," he told Discovery News. He was part of a four-person dendrochronology team from the Tree Ring Lab working on samples of the vessel's white oak planks and its hickory keel.
Other tree species used in the boat's construction included spruce and southern yellow pine, reported wood deterioration researcher Robert Blanchette of the University of Maine.
Looking up tree ring patterns for white oak timber samples is like hunting down a family's genealogy. To get the most accurate result, teams of people around the world need to have already done the manual labor of counting rings and entering forest timber chronologies into a database.
Then it's a matter of sleuthing through generations of tree life-cycles to find a pattern that fits: where the timber samples and the trees share the same local climate of wet and dry years allowing them to make matching patterns of wide rings and skinny rings. So where to start ?