Restoring Old Ironsides - frigate USS Constitution
A wonderful mixture of tomorrow's gadgetry and yesterday's workmanship is helping to refurbish this "floating forest," the most famous fighting ship in American history.
Charlie Deans is playing detective again. He motions for me to follow him into a darkened room, where he turns on a lightbox, wipes from the screen a gauzy layer of wood dust, and places on it a large piece of film. Taking a step back, he examines the image like a doctor analyzing an X-ray.
"Look at that," he says, grinning. "Thanks to four million volts of power, you're looking at wood that's buried 2 1/2 feet deep in the hull of Old Ironsides."
"Old Ironsides" is, of course, the USS Constitution, the most famous fighting ship in American history. Permanently docked at Boston's Charlestown Navy Yard, the ship draws a million visitors each year. As director of the Naval Historical Center Detachment Boston, Deans oversees the maintenance of the legendary 204-foot-long craft. These days, however, he is smiling because he's in charge of a once-in-a-lifetime project, the top-to-bottom refurbishing of Old Ironsides herself.
Every few decades the famous frigate must undergo a "D&I," which in official U.S. Navy parlance stands for "Drydocking & Inspection." Her masts, rigging, and guns removed and hull covered with scaffolds, Constitution has been drydocked since last July, resting on keel blocks and supported by shoring timbers. For nearly two years the ship will be thoroughly inspected. All rigging, copper-hull sheathing, and weak and rotten wood will be replaced and new mast sections made and refitted. The ship will "un-dock" early next year, and the $3.75-million project should be completed by mid-1994.
This D&I is particularly important, for not only is the work more detailed due to the upcoming 1997 bicentennial of her launching, but new technologies have given Deans and company new ways to inspect the ship's complex wood components. Using radiography and sonic and ultrasonic testing methods, workers are now able to peer deep into the ship's 21-inch-thick hull, even through three and four feet of planking and timbers, without boring a single hole or removing a single piece of wood. In addition, new emphasis is being placed on stockpiling the enormous timbers the ship requires for upkeep, an effort aided, ironically, by destruction caused in 1989 by Hurricane Hugo.
All of which gives Deans the chance to play detective.
"See this?" he asks, pointing to the radiograph of a joint in the ship's stem. Light flecks on the film are the remnants of nails, while other checks denote grain patterns. A long cylindrical shape is a metal fastener, one of some 25,000 copper pins--some up to 12 feet long--that hold the ship together. On the radiograph, crevice corrosion on the pin is clearly evident where the two pieces of wood meet, a natural funnel for saltwater intrusion.
Originally, Deans explains, the radiographs were designed to test the condition of the metal pins and fasteners that hold the timbers together. However, the clarity of the radiographs was exceptional, and a careful reading of the film brought added surprises.
"Look closer," Deans says. "Now, this is interesting." He points to a dark shadow on the film. Lighter areas mean the wood is more dense, for it takes longer for the radiation to pass through the fibers, he explains. Darker bands, therefore, denote wood of lesser density. "And if it's less dense," he says, "that means something is wrong; that something is fungus."
Five or 10 years ago, Deans says, the only way to find rotten wood so deep in the hull would have been through destructive methods of testing, such as boring holes and analyzing the cores. But with the radiography, new windows have been opened on wood that hasn't been seen in up to 199 years. All told, some 300 radiographs have been taken of the ship's hull planking and timbers.
In another breakthrough, the U.S. Forest Service's Forest Products Laboratory in Wisconsin used sonic testing to determine rotting characteristics of wood fibers far below the surface. In that process, Deans explains, sensors are placed on both sides of the wood to be tested, an "accelerator" is tapped with a hammer, and the time it takes for the sound to pass through the wood is measured.
Technicians from Wisconsin have come to Boston to test their equipment on the Constitution, and the Navy has sent the laboratory examples of live oak and white oak that exhibited deterioration. Using data from those initial tests as a baseline, Deans explains, they now have some very good ideas about the time it takes sonic waves to pass through various kinds of wood at various stages of deterioration.
"A lot of times," he says, "wood begins to rot from the center--it appears to be perfectly sound on the surface, but the core is rotted. With this method, we went through every one of the beams on this ship and the stem in the stern area, and found several deteriorated that we thought were OK. So we're replacing those."
Wood doesn't have to be ancient to rot, he explains. Perhaps the timbers were installed 20 years ago, but the wood was wet and green. That would be enough to start the destructive process. And unless boring samples had by chance been taken of specific affected areas, Deans says, there would be no way of uncovering the wood rot without this new technology.
Although the ship is undergoing a complete inspection, including the replacement of all 4.1 miles of standing rigging and much of the below-water-line copper-hull sheathing, wood plays the most prominent role in the preservation of Old Ironsides. In fact, the first problem to receive attention was a sagging in the ship's keel, a malady known as a "hog."
In the bottom of the drydock, Don Turner, the Center's production manager, taps the ship's keel with the metal tip of his measuring tape. The keel, a full 160 feet long, is comprised of the original four white oak timbers, each one 30 inches deep by 18 inches wide. Over time, the ship developed a "hog," an inevitable sagging of the bow and stern. The hog's stress is felt throughout the ship; large knee supports had pulled away from deck planking, doors no longer fit their frames, and water seeped through a hull whose ribs had loosened.
To fix the hog, Old Ironsides was settled in the bottom of the drydock on 31 concrete keel blocks, each topped with a metal frame filled with sand. Bit by bit, Turner says, sand is let out of those blocks and the ship's own weight--even stripped she's a prodigious 3.6 million pounds--forces the keel into its proper shape. According to Turner, more than 14 inches of hog have been removed. "She's settled completely now," he says.
But if working with existing wood on the ship poses special problems, the task of finding replacement wood can be even more exasperating--and require more detective work. Enormous timbers and planks are required during each Constitution D&I, and because technology allows an inspection of even more of the ship's fabric, more and more wood will be required during this drydocking.
All told, wood for the original construction came from all parts of the young country. Today, finding the right sizes and shapes of timbers to use in the maintenance and restoration of the ship requires forethought and imagination. When ships were routinely constructed of wood, the Navy stockpiled timbers. But with the advent of steel-hulled ships, the Navy let its stores of ship timbers become depleted. It takes a decade to dry out timbers with the huge dimensions required by Constitution, says Dean, and his crew is stockpiling live oak, white oak, and other woods in an Air Force hanger for the preservationists of tomorrow.
White oak used on Old Ironsides most often comes from Constitution Grove in Crane, Indiana, but it is live oak that is the most difficult wood to find in the sizes required for the ship. The stately live oaks grow short, squat, and gnarly, with lots of limbs, Turner says. Because the trees grow in such odd patterns, little strength is lost by cutting against or across the grain. While the long, straight-grained white-oak planks are used for hull planking, the live oak's large branch sections and odd shapes are required for knee supports, breasthooks in the prow, and curving "compass timbers."
The majority of the trees large enough to be used for those purposes are upwards of 200 years old, Deans explains, and are difficult to come by. For this most recent work, the city of Charleston, South Carolina, donated live oaks felled in 1989 by Hurricane Hugo, and other timbers have come from construction projects throughout the Southeast.
International Paper Company donated white and live oak from property it owns near Bainbridge, Georgia, after an employee read an article describing how oaks from Georgia's barrier islands were used in the original construction and an accompanying piece describing restoration needs. The trees were cut free of charge by a tree-harvesting firm working in the area, and the logs were stored temporarily at the Marine Corps Logistics Base in Albany, Georgia, before being hauled north.
It's a major undertaking, Deans says. "If we needed to replace a frame section today, we couldn't just go out and cut a piece of live oak." To air-dry a 12-inch timber to the required 12-percent water content takes approximately 10 years. "That's roughly a year per inch of wood," Deans says. "So we need to be gathering wood now for any work that may need to be done a decade away."
While planning for future preservation work is crucial, Deans, Turner, and company are also undoing historically inaccurate maintenance of the past. Much glue-laminated wood is being replaced with solid timbers, and, just as in the 1790s, joints of simple end-butting are now being lock-scarphed, a means of connecting two large timbers. "When the requirement to sail went away," says Turner, "a lot of these old techniques went away as well."
More and more of the preservation work will have to take place onsite as related industries fade out of existence.
Which means the docks at Charlestown's Pier No. 2 will showcase both new and old technology for several months. Onboard, Iridiumxx 192, a radioactive material used to get radiographs, is beamed through wood that has turned aside cannonballs from Barbary pirates and British warships. Inside the shop, yardarms and masts are hand-formed as if the past two centuries suddenly rolled away.
It's an exciting time for the Old Ironsides crew.
"We don't have many true icons of American history like Constitution," Deans says, his voice echoing in the concrete canyon of the drydock. "Because we were a young country in their day, prior generations probably did not have as much interest in history as we're seeing now. This ship is the oldest active navy vessel floating in the world today, and I think the farther we get from 1797, the more interested we'll be in 1797. And the new technologies of 1993 have been an incredible bonus."
He reaches up to knock on the original keel of the ship, a white-oak timber that has steered the vessel through 42 victories at sea.
"But you know, you still can't beat the old preservation methods," he says with a grin. "Salt water on wood--that's the best preservation technique around."
Watching new preservation techniques being used to solve old problems is a bonus for visitors to Old Ironsides. Each year nearly a million visitors come to walk the decks "once red with heroes' blood," as the poet Oliver Wendell Holmes wrote. They imagine themselves manning the cannons during a skirmish with Barbary pirates, or firing rifles on British warships from the fighting tops far up the masts. These days they find themselves watching history being preserved.
For the first time ever, the ship has remained open to visitors throughout the drydocking. A raised ramp with clear acrylic fencing puts visitors to the ship right on the edge of the dry dock, with a view of workers removing the starboard-quarter galley for repairs or replacing pin and fife railing with live oak from trees blown down by Hurricane Hugo. Inside an outdoor gazebo, closed-circuit televisions broadcast images of interior-restoration efforts.
"Now you can see more of the ship than ever before," says Commander Richard A. Amirault. With hull planks removed, the frigate's famous live-oak framing is visible; out of the water, you can actually see the original four-piece white-oak keel, laid in 1794 in the Edmund Hartt Shipyard in Boston's North End neighborhood. As you wander the open spar deck, workers pull copper pins that might date to the 18th century; nearby, huge hull planks are steamed and bent to match the tuck in the frigate's stern. "Normally, with the yardarms and her masts rigged, your eyes were brought up," Amirault says. "You didn't think about the 2 1/2 stories of ship below the waterline. Now you can see all of her. And she is beautiful."
WOOD FOR WAR
Because she was designed to sail into battle against superior forces, no expense was spared during the construction of Old Ironsides. The hull is nearly two feet thick, and constructed in three layers: The outer frame of white oak, laid horizontally from bow to stern, ranges from 4 1/2 to seven inches thick; the inner frame of live oak, laid vertically from keelson to bulwark, ranges from eight to 18 inches thick; and the inside frame, laid horizontally, of Douglas-fir 4 1/2 to seven inches thick, and white oak approximately 4 1/2 inches thick.
The ship's sails were made in Rhode Island, the copper sheathing in Boston. Nearly every state in the fledgling Union contributed something to the ship's original construction.
Woods used in the construction and preservation of Old Ironsides constitute a virtual forest. Among them are:
These trees grow with a gnarly grain pattern and many limbs, a response to the harsh environment of the southeastern coast.
How it's used: Framing, "compass timbers" or curved beams, breasthooks in the cutwater area, pin rails, and fife rails.
Where it comes from: Live oak is increasingly difficult to find in the sizes required for Old Ironsides, but trees have come from the wake of Hurricane Hugo in Charleston, South Carolina; as a result of land cleared for construction throughout the Southeast; and as a donation from a forest-products company.
The long, straight grain of white oak makes it superb for long planking; when cannonballs bounced off the hull of the ship, white oak provided the shield. A closed-cell structure renders it decay-resistant; white oak won't even absorb wood preservatives.
How it's used: Longitudinal exterior-hull planking,
inside planking wherever wood must be severely bent, and near the keelson,
due to its decay-resistant nature.
Where it comes from: Most white oak comes from the Naval Weapon Station in Crane, Indiana, where Constitution Grove was established in 1976 specifically to supply wood for Old Ironsides.
Many of the ship's original locust treenails, or trunnels, are still working fasteners.
How it's used: Treenails hold together many of the ship's wooden parts, such as the exterior planking to the ribs, or futtocks.
Where it comes from: The original locust treenails were from Massachusetts; today's are from wood grown locally.
Its relative abundance makes Doug-fir the wood of choice for the ship's masts, which were originally made of white pine from Unity, Maine.
How it's used: Each of the ship's three masts is made from four separate pieces of Douglas-fir, trunneled together with locust pins.
Where it comes from: West Coast.
This extremely hard wood is even more durable than live oak.
How it's used: The ship's sheaves, wooden blocks, belaying pins, and dead-eyes, all components of the rigging, are made of lignumvitae.
Where it comes from: South America.
In the last century, sugar pine has been used for cabinetry.
How it's used: In partitions, doors, etc.
Where it comes from: Grows locally.
Today longleaf pine has been supplemented by the more readily available Douglas-fir.
How it's used: The ship's original beams and decks were made from South Carolina longleaf pine.
Where it comes from: The longleaf used today grows in the Carolinas.
Bibliography for "Restoring Old Ironsides - frigate USS Constitution"
Eddie Nickens "Restoring Old Ironsides - frigate USS Constitution". American Forests. . FindArticles.com. 27 Dec. 2008. http://findarticles.com/p/articles/mi_m1016/is_n11-12_v99/ai_14795513