Point of Beginning

Requiem for a Schooner

April 26, 2008
Scanning the DNA of a national treasure.

Using the reflectorless mode in his Leica Geosystems TPS700 total station, Todd Croteau picks up details of the Wawona’s house.


When I showed up at the waterfront in the shadow of the Space Needle one freezing November day in 2007, I was collared by an onlooker. “Thank God she’s been saved!” he said. “We’ve been watching her go downhill for years. At last, somebody’s come to her rescue.” But those of us on the job were not so sure of her reprieve.

The Wawona, a 156-foot three-masted lumber schooner built in 1897 and moored on the south end of Seattle’s Lake Union for the last 20 years was clearly on the way out. While small details persisted as survivors of the Wawona’s launch 110 years ago, such as the Turks head on the king post of her steel wheel and the bronze sheet metal tacked on the threshold of her companionway, her hull was rotting, entire planks were missing and she had a gaping hole at her bow where the port planking had parted from the upper stem. Her vast deck of gray-checked fir 2x4s leaking oakum and tar was covered haphazardly with random plywood shapes. Having outweighed their decaying partners long ago, her masts were floating in the water and had been replaced onboard by utility pole stubs. Her house was covered in flaking white paint, and the elegant crowned oak panels of her salon and cabins dipped their lower moldings in an inch of standing water.

We were at once struck by the grand mass of her floating presence and the colossal time, money and skill demands that any serious restoration would take. She was occupying prime waterfront real estate in a very happening section of 21st-century Seattle: an old lady in fast company where her welcome was quickly wearing out. She was soon to be dry-docked, cut apart and her pieces supposedly stored away for possible reconstruction as a maritime memorial. Our team set out with digital photography, a total station and a 3D laser scanner to preserve a virtual Wawona while the real one was still on the scene. Our technology choices skipped a generation--we had no use for GPS as precision was crucial but accurate positions were not.

Framed by one of the vessel’s masts and Seattle’s Space Needle, Croteau braves a gale on the afterdeck of the Wawona.

Foundering

Despite the valiant efforts of the Wawona’s sponsors at the Northwest Seaport, Seattle provided no appropriate ransom for her preservation. Her destruction seemed imminent. But how could present-day technology preserve her essence for future generations? One could measure her and create a set of line drawings. In fact, in 1985, the Northwest Seaport measured the Wawona’s lines, hand-drafted them on mylar and generated a table of offsets that would enable a shipbuilder to re-create the outside surface of her hull, but no construction details or plans of the deckhouse were drawn. With our modern digital tools, we would be the ones to fill in those and other details. Our digitally photographed records and scanned surface file, with a resolution that captured the scars on her decaying planks and the carving inside her house, would enable future viewers and data miners to re-create a virtual Wawona.

The Wawona in happier days--when she was maintained in drydock with a cover fitted over her deck.

All Hands on Deck

Funded by the Seattle Parks and Recreation Department, our crew had the task of taking the Wawona’s measurements for the United States National Archives. Overseeing the entire archiving process was Todd Croteau, maritime program coordinator for the Historic American Engineering Record (HAER), a division of the U.S. National Park Service. Along with Chris Payne, a New York historic structures photographer, Croteau sketched and photographed structural and mechanical details throughout the vessel. On behalf of Informed Land Survey of Tacoma, I provided the survey control on and off the vessel using a Leica Geosystems ( www.leica-geosystems.us ) TPS700 total station. Armed with a Leica ScanStation, Scott Roed from Kuker-Ranken’s Seattle office scanned the deck, hold and cabins. And Tacoma’s Bates Technical College provided us with four good-humored and stalwart volunteers, Mike Medford, Erick Hensel, James Wingate and Zack Malloy, who worked tirelessly and without complaint in the cold. Not only did they keep the rest of us amused and free from heavy lifting, their questions and comments made us think about best practices for the project, including the repeating of angles and checking of backsights religiously as well as keeping track of the deflections of shipboard control.

The main cabin shows that the ship’s joiners were capable of elegant work.

Unsteady As She Goes

Those in the geodesy game know that we’re floating around on loose tectonic plates on a seething sea of magma. But when you’re on a 156-foot schooner free-floating in the waters of Lake Union, you really begin to notice everything moving relative to everything else--and it all happens in real time. For one thing, the boat is translating and rotating relative to the shore, more so in wakes and winds. For another, the hogged structure of the schooner is not a rigid body and moves with a wringing motion along the fore and aft axis, which shows up as random error in the control. The overall rolling motion tended to trip level monitors in both the total station and the laser scanner. Therefore, work was far easier in the mornings and evenings after sunset when winds were calmer.

Kuker-Ranken’s Roed, our master scanner, had the toughest duty of all: putting the 65-pound scanner--sometimes on a tripod and sometimes not as clearances would allow--into tight, slippery and highly sloped spaces inside the hull. It was awkward and marginally hazardous, and we thanked our good fortune for having the Bates volunteers on hand to help. Further, uncertain orientation from ambient motion left Roed with a number of scan ambiguities that needed to be post processed.

A scan of the Wawona’s transom.

I set a dozen mutually visible control points the length of the deck on the centerline and on both port and starboard sides, then dove down into the hold and shot another dozen below. Paul Mabry, PLS, owner of Informed Land Survey, adjusted my control network using Carlson ( www.carlsonsw.com ) Survey 2007. Roed used these positions as control and wrote the following about post processing:

“After all the scans were taken on the ship, the next step was to geospatially reference all of the individual setups into one model. This was done off-site where there was power, lights--and heat. With the Leica ScanStation, this process took no time at all for three separate registrations thanks to the ScanStation’s ability to setup and backsight over known control points. This was done by creating a registration in Leica’s Cyclone suite of software and then adding the wanted setups and known coordinates. Then, just by pushing the “Register” button, all selected point clouds were geospatially referenced together on the datum established by the control point coordinate system.

“After evaluating the residual errors for each coordinate pair and determining that all were within project specifications, we just needed to accept or “freeze” the registration. After opening the newly created “Scanworld,” we cleaned up the final model by deleting all unwanted points. In this project, that was all that was needed because the client was going to go through the model, set points and draw polylines in their drafting software. This combined dimensionally accurate model was saved electronically for archival purposes and is available if any new data extractions are needed at a later date.”

Our efforts have resulted in enough scans and photos of the Wawona’s deck, cabins and the inside of the hull to produce a total virtual model, which will be housed in the Prints and Photographs Department at the Library of Congress and available to the public through its “Built in America” Web site at http://memory.loc.gov/ammem/collections/habs_haer/

The finished scan--millions of points stitched together.

Uncharted Waters

As of last month, the Wawona still floats at her mooring in south Lake Union, a nautical white elephant with an uncertain future. Yet through the efforts of a few surveying professionals and some modern technology, her essence will abide so long as hard disks spin and Internet nodes send packets. Perhaps plutocrats in the 22nd or 23rd century will amuse themselves by having her built again, no doubt with carbon fiber sails and bioengineered bamboo planking. If they do, our efforts from last November will make her the ship she once was--imposing, graceful and altogether magnificent.

The Wawona in November 2007 with the Center for Wooden Boats, Seattle’s hands-on maritime heritage museum, in the background. The freshwater of Lake Union has not been kind to the vessel.

Sidebar: About the Vessel

The three-masted Wawona is the largest sailing schooner built in North America. Constructed by Hans Bendixen at Fairhaven, California, she began her career in 1897 as a lumber ship, making quick runs up and down the Pacific Coast. In 1914, after 17 years of carrying lumber, she became part of the codfishing fleet that operated in the Bering Sea. By 1940, her crews had caught 6,830,400 codfish, a world record for a catch by a single vessel. Conscripted during World War II for government use as a barge, she was re-rigged in 1946 and had two last seasons of codfishing. The Wawona then sat in port for nine years. In 1952, Capt. Ralph E. Petersen sought to turn Wawona into a South Seas cruise ship, but this plan ended due to a lack of funds. Even her 1953 purchase by cattle rancher William Studdart and film star Gary Cooper failed to return her to the sea. The pair had planned to export beef cattle to the Soviet Union, but the deal fell apart during negotiations with the Russians. Fortunately, California’s new maritime museum sparked public interest in rapidly disappearing historic ships and the public raised the money to save the Wawona from demolition. In 1964, Seattle’s Northwest Seaport purchased her in order to create a maritime museum for Puget Sound. The last member of the Northwest’s commercial sailing fleet, the Wawona is associated with an industry that shaped the growth and history of the Northwest.



Source: National Park Service, www.nps.gov/history/nr/travel/seattle/s4.htm .

Sidebar: Broadening Horizons

“I never thought when I started at Bates we’d be doing anything like this,” said student Zack Malloy. I wasn’t sure if Zack was excited about the project or just very cold. Clearly, working on the digital archiving of the Wawona was not the meat and potatoes of the average surveying firm or the type of job you would study for the LSIT. However, it represented the new world that is opening up for young surveyors. Professionals work on more interesting jobs these days--more interesting than just section, township and range projects--which should be shared with students. Today’s surveyors use CAD and road layout software to map waypoint trails for commercial airliners to land safely and total stations to aim cell tower antennas. Scanning a historic vessel is yet another application for students to learn from--and maybe even participate in.