As reasons for shipwreck exploration change, so does technology
ALPENA — As the home to Thunder Bay — site of more than 200 shipwrecks — Northeast Michigan has a long held history and fascination with shipwrecks.
Over time, divers say, shipwreck-finding technology has changed as have the reasons people look for shipwrecks.
Where it was once considered a salvaging endeavor to retrieve valuable items, finding shipwrecks now has to do with preserving the history of a wreck for future generations.
Wayne Lusardi, a maritime archaeologist with the Michigan Department of Natural Resources, said the shipwrecks themselves were valuable and there were companies that specialized in salvaging shipwrecks and reclaiming the valuable cargo.
“Of course the shipwrecks are valuable — or can be valuable — their cargo can be valuable,” Lusardi said. “And so the owners or the insurers that wanted to get hold of them. In the 19th century, there were a lot of salvage companies that operated on the Great Lakes that went looking for shipwrecks specifically to recover them to profit off of them.”
Lusardi said early recovery methods included dragging an anchor across the bottom of the lake, looking down into the clear water or sending divers into the water.
“A lot of them was simple stuff where they’re really just putting anchors over the side and dragging them around until they hit something other times you’re just looking the water is clear enough often that you can just do a visual survey and try to find something sometimes the masts were sticking out of the water still right after the wreck happened,” Lusardi said. “But usually it was a dragging operation that attempted to find the wrecks and depending on how deep they were 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 hard hat divers and bell divers in the 1890s.
Artifacts from divers such as helmets and salvaged items can be found in the Great Lakes Maritime Heritage Center.
If dragging anchors along the bottom didn’t work, Lusardi said, they’d use two tug boats with a chain between them that they’d drag along the bottom of the lake. A lot of the scars from this sort of operation can be found around shipwrecks such as the Pewabic.
Lusardi said commercial endeavors to salvage shipwrecks went on until the late 1970s, but now the focus has shifted to preserving wrecks and preserving history.
“When they first started salvaging they weren’t really interested in the preservation of the wreck; they were looking at it as a commercial endeavor,” Lusardi said. “So if a big boat went down with iron ore for example the iron or cargo was very valuable and if you could recover that cargo you could sell it and they can make a lot of money. They weren’t considering them historic resources or anything, they were considering them places for financial gain.”
The technology used in finding shipwrecks has changed over the years too.
Lusardi said most older shipwreck technology was pretty simple.
“Originally back in the day after a ship sank there was pretty basic methodology to go look for them,” Lusardi said.
Lusardi said a lot of shipwreck-finding technologies used today — including sonar and radar — were developed around World War II.
Two of these technologies are sonar and magnetometers. Lusardi said sonar uses sound waves that are emitted from “a torpedo looking device.” These waves bounce off the bottom of the lake to a computer system that gives a three-dimensional view of what the lake bottom 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 oftentimes caused by iron, Lusardi said. Things such as ship wheels, propellers, and big boilers can be found this way. Lusardi said ships used this during the war to look for submarines.
This technology takes a lot of time because you are “going back and forth mowing the yard” Lusardi said. Both of these technologies were developed around the same time in the 1940s.
“In the 20th century, there were a lot of technologies that were developed right around World War II, like sonar, radar and things like that that can fine tune kind of the way you go around finding shipwrecks,” Lusardi said. “And that’s something that has evolved considerably over time and that’s exactly the kinds of instruments we use today, a lot of these World War II kind of relics.”
Lusardi said searching for shipwrecks usually starts in libraries, archives, and newspapers to find where they went down.
“Trying to figure out exactly where they went down or as close to that position as possible before you just go scrambling out in the lake and start looking for things,” Lusardi said. “You’ve got to do that work ahead of time.”
Lusardi said a lot of Great Lakes salvagers learned to dive through the armed services.
“Other divers learned to dive from the commercial diving schools around the country,” Lusardi said. “And usually the basics behind it are just a few months but then you have to kind of advance to different kind of techniques and training and kind of keep up on it and be proficient.”