Shipwreck enthusiast creates a 3-D model of a boat in Lake Minnetonka

With the technology Ken Merryman uses, you can examine a sunken ship from all sides without getting wet. You can even create your own mini-version of the shipwreck to hold in your hands or display on your mantel.

But Merryman has considerably higher goals than living-room décor. The co-founder of the Great Lakes Shipwreck Preservation Society wants to create 3-D models of shipwrecks to safeguard high-quality images of maritime history, even as the physical wrecks themselves slowly but inevitably decay. This winter he is completing a 3-D model of the Hopkins, a streetcar boat at the bottom of Lake Minnetonka.

"We look at this as a way to document and preserve what's there," said Merryman, a retired computer engineer from Fridley. "There's a story with every wreck, and the oldest ones have great stories."

The Lake Minnetonka project is essentially a trial run before scanning the Hamilton and Scourge, two ships that sailed in the War of 1812 and sank in a sudden squall on Lake Ontario in 1813. Now under 300 feet of water, the wrecks have been little explored. Merryman hopes to create 3-D models of them.

Merryman and a group of volunteers last spring began diving with a video camera to scan every inch of the Hopkins' exterior. A technology called photogrammetry uses software that assembles the images into a high-resolution 3-D digital scale model. On a computer screen it's a picture that spins to show the wreck from every angle; a 3-D printer can turn it into a tangible object.

Merryman and other divers were at the lake Saturday to plunge beneath the ice and scan the Hopkins for sharper images. Using a still camera, they took 2,600 photos while swimming back and forth around the wreck. A remotely operated camera could do the job, he said, "but you get a lot better results with a diver and a good camera."

The Hopkins, scuttled in 1949, lies in only about 60 feet of water. But Merryman said its size and surrounding conditions resemble those of the Hamilton and Scourge. And the water under the ice Saturday, shadowed as it was by the snow on top, closely mirrored Lake Ontario's depths.

"I have been working on the project for over a year now with no guarantee that we will be able to do it," he said.

Despite Minnetonka's chilly waters, this is a good time of year to dive. The lake is clear enough in winter and early spring to accommodate video scanning; in summer and fall, the water is too murky to yield good pictures.

Photogrammetry 3-D technology is widely used on land as well as underwater. The Smithsonian Institution, for example, has created 3-D models of artifacts in its vast collection, from a cast of Abraham Lincoln's face to the skeleton of a woolly mammoth. It enables people to examine the objects remotely and, in some cases, reproduce them with a 3-D printer.

The National Park Service has been using photogrammetry to document shipwrecks, said Brett Seymour, deputy chief of the Park Service's Submerged Resources Center. With a 3-D model and no water in the way, "an archaeologist can study the wreck, see what damage has been done and any number of things," he said.

Merryman, 69, has spent 50 years diving shipwrecks. The shipwreck society, formed of like-minded lovers of maritime lore, searches the lakes for wrecks and has studied about 20, eight of which are listed on the National Register of Historic Places.

David Mather, an archaeologist with the Minnesota State Historic Preservation Office, said the society does careful work and has been helpful in getting shipwrecks listed on the National Register. "They're a great grass-roots preservations group," he said.

Merryman is widely respected as a shipwreck enthusiast, Seymour said. Some shipwreck hunters are in it for the glory or to engage in illegal looting, he said. But Merryman is different.

"His interest in finding them but wanting to preserve them, and wanting to keep them intact, is something I think is incredibly honorable," Seymour said.

Katy Read • 612-673-4583