Giant freeze dryer to preserve famous shipwreck

La Belle hull on the dry seabed, taken from the cofferdamTexas A&M University has been working to preserve the shipwreck of La Belle, 1 of 4 ships carrying French explorer Robert de La Salle and 300 other souls in his ill-fated 1684 mission to the Gulf of Mexico. The shipwreck was discovered in 1995 by researchers from the Texas Historical Commission. Its excavation was a huge production requiring a very expensive cofferdam, dozens of archaeologists and 2 years of on-site work.

The hull of the ship was salvaged from the sea floor and sent to Texas A&M’s Nautical Archaeology Program where they kicked off its conservation with a decade-long soaking in polyethylene glycol (PEG), a polymer that replaces the water in wood ensuring it doesn’t warp or shrink when it dries.

The problem with this method, which has been used to preserve ships from the Mary Rose to the Vasa, is that it takes a long time to work. More recently, a new problem has arisen: the price of petroleum-based products like PEG has skyrocketed. The original estimate for La Belle’s wood stabilization was $330,000. They had to increase it to $1.4 million solely because of the rising cost of PEG.

That’s when a little ingenuity and Texan affinity for a) large things, and b) cattle came to the rescue. Texas A&M is going to use a gigantic freeze dryer more commonly used to freeze dry several whole cows at a time to freeze dry the hull all at once.

The entrance to the giant freeze dryerThe massive freeze dryer, at 40 feet long with an 8-foot internal diameter, is the largest such machine for conservation use in the hemisphere, says Peter Fix, the maritime center’s assistant director and project conservator for the La Belle.[…]

“We will take a piece of the ship, make a mold for each piece of timber to accurately mimic the curvature of the hull, put it in the freeze dryer and in four to six months, the freeze-drying process will slowly sublimate the water from the timber,” says Fix. “It’s a much gentler process than straight dehydration, and it is slightly revolutionary in that no one has tried it before. An awful lot of engineering and understanding of the complex shapes of the ship have to be compensated for in advance of freeze-drying.”

Donny Hamilton, head of the university’s anthropology department, says the new method will reduce the preservation time by about three years and cut the costs by more than a half million dollars.

The university hopes to amortize the half million dollar cost of the freeze drier by using it for future preservation projects, both historical and in response to disasters like floods. Once the ship comes out of the freeze dryer, it will be kept in storage until the museum’s reconstruction in 2013. The new museum will not only have La Belle on display, but also many of the million or so individual artifacts recovered from the wreck site.

La Salle wanted to start a French colony at the mouth of the Mississippi which would be well-positioned to steal Spanish silver. (It’s amazing how many Europeans came to North America specifically to pirate Spanish loot.) Unfortunately, he had no real idea of where the mouth of the Mississippi actually was, and he didn’t know how to navigate the tricky Gulf currents or the restless natives. When he arrived at what is now Matagorda Bay on the southeast Texas coast in 1685, he was 400 miles west of the Mississippi.

First his storeship, L’Aimable, ran aground, then La Belle (onto which they had transferred all the contents of L’Aimable they could salvage) sank. La Salle and the few remaining colonists founded what is now Victoria, Texas. They went North several times, still looking for the mouth of the Mississippi until finally La Salle’s 36 men mutinied and killed him in 1687. The mutineers stayed where they were, in present-day Navasota, Texas, for a year. In 1688, the 20 adults still surviving were killed by Indians.

6 thoughts on “Giant freeze dryer to preserve famous shipwreck

  1. What is with these mysterious homework assignments I see in the comment sections every once in a while? :confused:

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