The William B. Davock sank on what's been termed "the most disastrous day in the history of Lake Michigan shipping," but why the freighter and its 32 crewmen went down amid 80mph winds and 30-foot waves has been a 75-year mystery. WZZM reports a sudden blizzard blew in on Nov. 11, 1940, and while smaller ships survived, three larger ones were destroyed. Three divers found the Davock—upside down and with coal scattered around it—32 years later. But its resting place 210 feet below the lake's surface put it in waters so murky that an investigation into why it sank was all but impossible, Michigan Live reports. On a clear day last fall, however, divers from the Michigan Shipwreck Research Association captured the first known footage of the wreck and evidence of a fatal blow: a broken rudder and snapped propeller blade.
"The waves were so strong, they must have snapped the rudder's connection, at which point it swung so far over that it struck the propeller," says MSRA diver Jeff Vos, who filmed the wreck. "With no power or steering, the Davock would have been at the mercy of the storm." MSRA board member Craig Rich says the Davock "would have gone into the trough of the wave sideways, which would have swamped the ship." The MSRA notes the ship may have capsized before sinking. Interestingly, divers may owe their discovery to invasive zebra mussels, which have made Lake Michigan's murky water more clear in recent years. "It's not as warm as it is in the Caribbean, but it's certainly starting to rival it in clarity," Rich says. "The divers didn't even use a light for the discovery." (Meanwhile, archaeologists are uncovering the gruesome aftermath of a wreck in Australia.)