Searching for sunken 16th century ship
Photo Michelle Le/The Almanac
By Dave Boyce - Almanac News
Inductive reasoning. It's what detectives use to work backwards from evidence at a crime scene to develop a chronology of events that, with luck and diligence, will lead to a suspect.
It's also the modus operandi for Portola Valley resident and geophysicist Sheldon Breiner and a team of archaeologists and a historian who meet periodically along the Mexican coast of Baja California.
They're investigating the disappearance of a Spanish galleon believed to be the San Felipe.
The San Felipe left China in 1576 headed for Acapulco by way of Manila with a cargo that included silk, beeswax and tons of Ming Dynasty porcelain.
Records show the details of the cargo but not the San Felipe's arrival at its destination, and the Spanish were meticulous with their records, Mr. Breiner says in an interview.
Mr. Breiner spoke about this exploratory adventure at Portola Valley's Historic Schoolhouse on Nov. 16. The town's Nature & Science Committee sponsored the free event and about 20 people showed up.
Shipments of porcelain left China for Spain twice a year for some 250 years starting in 1565, Mr. Breiner says. There is debris indicating that the 100-foot, 400-ton San Felipe may have run aground off the desert coast of Baja.
Lying on and under the shifting sands of this corner of Mexico's Sonoran Desert are about 1,000 artifacts. While the researchers haven't yet found any silk, which would have been encased in wax, they have found beeswax, some lead sheeting used on the hulls of 16th century ships to discourage underwater pests, and a great many pieces of porcelain scattered along a two-mile-long line in the sand, Mr. Breiner says.
Why might the ship have grounded ? Strong prevailing winds, scurvy among the crew of 200, a need for food or water, or a new mast or spar -- the reasons are not known. Had the ship reached Acapulco, its cargo would have been offloaded and hauled overland to the Gulf of Mexico and then shipped to Spain, a two-year to three-year trip altogether, Mr. Breiner says.
With hundreds of thousands of years of predictable winds, waves and depositions of sand as reference points, the line of debris is readable.
The team has worked backward from the locations of these artifacts to place the likely remains of the sunken hull. After scanning the area with an ultra sensitive magnetometer, the team now has tracking data showing magnetic anomalies consistent with a buried hull. In short, they have a strong suspicion as to where it is.
If this anomaly is a sunken galleon, it may never be known for certain whether it is the San Felipe. Ship owners back then did not paint names on hulls, Mr. Breiner says.
The porcelain can be dated by experts skilled at matching a design with the year in which that design was current.
Mr. Breiner says he plans to return to the site in February to survey the wreckage in detail and create a grid-based map of the debris field.
The magnetometer can detect ballast stones, cannon barrels, and iron spikes used to hold the ship's ribs to its keel.
Other items with a smaller footprint but still detectable include weapons, tools, boxes, furniture parts and personal effects of the crew. The lack of oxygen under the sediment inhibits corrosion.