`Old Ironsides' Gets a Modern Overhaul
WHEN Joshua Humphreys designed the United States frigate Constitution during George Washington's presidency, he probably didn't envision a celebration for her 200th birthday.
But with that date approaching in a little more than three years, the 18th-century ship is getting a taste of state-of-the-art technology as she undergoes a scheduled dry-docking for maintenance and repairs.
Although ``Old Ironsides'' had been overhauled routinely before she was dry-docked this time in 1992, never before has the US Navy so extensively combined the ship's historical attributes with 20th-century inspection techniques.
Original live-oak framing and copper fasteners possibly forged by Paul Revere are suddenly in close quarters with sonic testing, ultrasonic testing, and X-rays.
Charles Deans, director of the Naval Historical Center Detachment Boston at the USS Constitution facility, has overseen this high-tech testing. He notes that ``with our inspections and with the help of the technology, we've determined that we won't need a major repair period [that was scheduled] at the turn of the century.''
Sonic testing, Mr. Deans says, has evaluated the condition of every major timber on the ship. By measuring the amount of time it takes for sound to travel through a piece of timber, rotting areas - which slow down the speed of sound - have been identified. This method has identified an additional 10 or 11 timbers needing replacement that wouldn't have been caught otherwise.
Ultrasonic testing - a technique similar to sonic testing, except that the sound travels much faster - has eliminated the need to remove 600 copper fasteners for samples of their overall condition, Deans says. Removing the fasteners disturbed timbers and other elements on the ship and risked missing fasteners that needed to be replaced. Ultrasonic testing, on the other hand, has enabled every fastener on Old Ironsides to undergo inspection.
But this technique has not been completely accurate in identifying problems with fasteners, Deans says. In at least one case, ultrasonic tests indicated a fastener in good condition, when in fact it was broken.
To overcome these inaccuracies, technicians are using a third technique: X-rays. Deans says that this method not only reveals exceptional detail in the fasteners, but also shows a great deal about the wood quality. The method has given the Navy a permanent record of the condition of the keel, stem, and stern post.
Each of these techniques, Deans admits, has its drawbacks and potential for error. But he is confident that together, the tests produce a 100 percent accuracy rate in evaluating the ship. ``We haven't found a flaw in them yet,'' he says.
Even with the availability of such advanced technology, some maintenance on Old Ironsides is only possible using centuries-old techniques.
Replacing and repairing the ship's rigging, for example, requires some tools and methods that have remained unchanged for 600 years.
Dave Mullin, one of the ship's riggers, emphasizes that all the rigging must be ``historically correct'' and be able to withstand hurricane-force winds.
Richard Amirault, the ship's commanding officer, also notes the attention paid to the ship's historical attributes: ``Our philosophy is we are not going to repair it unless we repair it historically accurately,'' he says.
In some cases, emphasis on authenticity can become complicated. Commander Amirault indicates one such challenge when he describes replacement of the ship's live-oak planks, which constitute a large part of the ship's framing.
Since live oak has no commercial value, it cannot be obtained commercially; the Navy thus accepts donations of large pieces of the wood, mostly from private individuals who have the trees on their property.
Obtaining the live oak is only half of the challenge. The wood must dry for about 10 years before it can used on the ship. Wood obtained now, therefore, will be used in a subsequent overhaul of the Constitution.
Although at times adhering to authentic materials and methods may be difficult, at other times it has revealed hidden benefits.
In thoroughly researching the structure and history of the ship, for example, the Navy has realized that Joshua Humphreys originally designed the ship with a unique feature: 16 diagonal riders, wooden planks that form a sort of rib cage in the hull's interior.
With additional research, Deans says, the Navy learned that the diagonal riders were at least partially designed to combat hogging, a common problem in which the keel bends upward at midships and sags at the bow and stern.
Following the original specifications and hoping to reduce the Constitution's hogging problems, the Navy is installing eight diagonal riders on each side of the ship.
What's interesting to note, though, is that this 200-year-old architecture closely resembles a composite space-frame system, which Deans says has recently been conceived and designed to lessen hogging problems. The composite space frame is so recent, in fact, that its so-called new technology is still unproven - and the Navy decided against implementing it in the Constitution.
Utilizing all this high technology - along with some more classic methods - has brought the ship to about the halfway mark in its overhaul.
Even while it is in dry dock, Old Ironsides has remained open to visitors, Amirault notes; now, in fact, may be the time to tour the ship, since more of it is actually visible in dry dock than will be when the ship returns to its watery home in Boston harbor.
Although the Constitution remains a commissioned warship, all this maintenance work is certainly not just for the Navy's benefit.
As the ship approaches a milestone, Amirault reflects, it ``has reached a point where it's not the Navy's ship. It's everyone's ship.'' And he expresses his hope that all the high-tech maintenance work will not only see Old Ironsides through her 200th birthday, but through her 300th as well.