As the reasons for exploring wrecks change, so does the technology | News, Sports, Jobs
ALPENA – As home to Thunder Bay – site of over 200 shipwrecks – northeast Michigan has a long history and a fascination with shipwrecks.
Over time, divers say, wreck search technology has changed, and so have the reasons people search for wrecks.
While it was once seen as a salvage business to salvage valuables, the search for wrecks is now tied to preserving the history of a wreck for future generations.
Wayne Lusardi, a marine archaeologist with the Michigan Department of Natural Resources, said the wrecks themselves were valuable and there were companies that specialize in salvaging wrecks and recovering valuable cargo.
“Of course wrecks are valuable – or can be valuable – their cargo can be valuable,” Lusardi said. “And therefore the owners or the insurers who wanted to appropriate them. In the 19th century, there were many salvage companies operating on the Great Lakes that searched for shipwrecks specifically to salvage and profit from.
Lusardi said early recovery methods included dragging an anchor to the bottom of the lake, staring into clear water, or sending divers into the water.
“A lot of them were simple stuff where they just put anchors on the side and drag them around until they hit something other times where you just watch that the water is clear enough to that you could just do a visual survey and try to find something, sometimes the masts would come out of the water right after sinking,” Lusardi said. “But usually it was a dredging operation trying to find the wrecks and, depending on their depth, they could put divers on them.”
He said the Pewabic – a freighter that sank off Thunder Bay Island in Lake Huron in 1865 – was explored by divers wearing helmets and divers in the 1890s.
Diver artifacts such as helmets and salvaged items can be found at the Great Lakes Maritime Heritage Center.
If dragging anchors along the bottom didn’t work, Lusardi said, they would use two tugs with a chain between them that they would drag along the bottom of the lake. Much of the scarring from this type of operation is found around wrecks such as the Pewabic.
Lusardi said commercial efforts to save shipwrecks continued until the late 1970s, but now the focus is on saving wrecks and preserving history.
“When they started salvaging, they weren’t really interested in preserving the wreckage; they viewed it as a business venture,” Lusardi said. “So if a big ship was sinking with iron ore, for example, the iron or the cargo was very valuable and if you could salvage that cargo, you could sell it and they could make a lot of money. They didn’t consider them not as historical resources or anything, they saw them as places of financial gain.
The technology used to find wrecks has also changed over the years.
Lusardi said most old sinking technology was pretty straightforward.
“Originally, in the aftermath of a sinking ship, there was a pretty basic methodology to pick them up,” Lusardi said.
Lusardi said many of the wreck-finding technologies used today — including sonar and radar — were developed around World War II.
Two of these technologies are sonars and magnetometers. Lusardi said the sonar uses sound waves emitted from “a torpedo-like device”. These waves bounce off the bottom of the lake to a computer system that gives a three-dimensional view of what the bottom of the lake looks like.
“If there’s a shipwreck on it, you’re going to see it,” Lusardi said.
Magnetometers detect deviations in the Earth’s magnetic field often caused by iron, Lusardi said. Things like ship wheels, propellers, and big boilers can be found this way. Lusardi said ships used it during the war to search for submarines.
This technology is time-consuming because you’re “going back and forth mowing the yard,” Lusardi said. These two technologies were developed around the same time in the 1940s.
“In the 20th century, a lot of technology was developed during World War II, like sonar, radar and things like that that can refine the way you move around to find wreckage,” Lusardi said. “And that’s something that’s evolved tremendously over time and that’s exactly the kind of instruments that we use today, a lot of these sort of WWII relics.”
Lusardi said the search for wrecks usually begins in libraries, archives and newspapers to find where they are descended.
“Trying to figure out exactly where they fell or as close to that position as possible before you rush into the lake and start looking for things,” Lusardi said. “You have to do this work in advance.”
Lusardi said many Great Lakes rescuers learned to dive from the armed forces.
“Other divers learned to dive at commercial dive schools around the country,” Lusardi said. “And usually the basics behind it only last a few months, but then you kind of have to progress to different kinds of techniques and training and kind of keep going and be proficient.”