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This week marks the 50th anniversary of the sinking of the SS Edmund Fitzgerald, a 729-foot ore carrier that sank during a storm on the night of Nov. 10, 1975, in Lake Superior. Twenty-nine crew members died.

The carrier was loaded with more than 26,000 tons of iron ore pellets when it departed Nov. 9 from Duluth, Minnesota. The ship was headed east across the lake, bound for Zug Island in Detroit, when it encountered a midlatitude cyclone that was said to have generated winds of 84 mph and towering waves.

The sinking would usher in a wave of maritime safety reforms, including weather forecasting, vessel engineering and emergency procedures. It also became cemented in the public consciousness thanks in part to a hit song by Gordon Lightfoot.

What was the route of the Edmund Fitzgerald?

After being loaded with 26,116 tons of taconite, a low-grade iron ore, at the Burlington Northern Railroad Dock in Superior, Wisconsin, the Fitzgerald departed at 2:15 p.m. Nov. 9 under the direction of Capt. Ernest McSorley.

But the Fitzgerald wouldn't travel alone. A second freighter, the SS Arthur M. Anderson, helmed by Capt. Jesse Cooper, departed Two Harbors, Minnesota at 4:30 p.m. The Anderson would stay 10 to 15 miles behind the Fitzgerald as they traveled eastward, and the two captains would stay in sporadic radio contact until the end.

As the journey wore on over the roughly 29 hours from the FItzgerald's departure, weather conditions continued to deteriorate. At around 2 a.m. Nov. 10, severe storm warnings forced both ships to deviate from the shipping lanes along the south shore of Lake Superior and follow a more northeasterly course. At 3:30 p.m., McSorley reported having lost a railing and two vents and said the ship was listing. Forty minutes later, the Fitzgerald reported a loss of its radar.

At 7:10 p.m., in what would be the final transmission from the Fitzgerald after the Anderson asked how the ship was doing, McSorley reported, "We're holding our own."

The Edmund Fitzgerald sank on the Canadian side of Lake Superior, roughly 17 miles from the entrance to Whitefish Bay, Michigan.

A U.S. Coast Guard report released in July 1977 noted a "large quantity of debris" that included lifeboats "and other flotsam" was all that remained when the Anderson caught up to the Fitzgerald's last known coordinates. No survivors or bodies were recovered.

How big was the Edmund Fitzgerald?

When it launched from the Great Lakes Engineering Works in River Rouge, Michigan, in 1958, the Edmund Fitzgerald was the largest ship in the Great Lakes. For roughly a year, the 729-foot vessel was dubbed "Queen of the Great Lakes," a title conferred on the largest ship. It would hold the title only until September 1959.

The Fitzgerald was nearly 285 feet shorter than the current Great Lakes record-holding MV Paul R. Tregurtha, a 1,013-foot, 6-inch bulk carrier freighter launched in February 1981.

The ship was named for the chairman of Northwestern Mutual Life Insurance Company, which commissioned and owned the ore carrier.

Why did the freighter sink?

The Edmund Fitzgerald's sinking was quick. The Coast Guard report noted that no lifeboats were deployed and no distress call was sent. The ship likely went under just minutes after Capt. McSorley's final reply to a status check from the Anderson.

The Coast Guard's Marine Board of Investigation report was one of two major federal investigations into the accident. The other was commissioned by the National Transportation Safety Board. Both inquiries pointed to faulty hatch covers as the likely cause. The Fitzgerald had 21 such covers, each sealed shut with steel clamps.

The Fitzgerald was riding lower with a heavy load and showing signs of taking on water with a reported list. With some estimates putting wave heights as much as 35 feet, weakened hatch covers would have been vulnerable to such waves.

The NTSB report said that "the probable cause of this accident was the sudden massive flooding of the cargo hold due to the collapse of one or more hatch covers."

There was little else to go on, and the shipwreck has attracted a range of other theories in 50 years, including a rogue wave, the ship bottoming out on a shoal, structural flaws, and failure of the hatch covers.

Contributing: Doyle Rice

SOURCES NTSB report; U.S. Coast Guard report; Detroit Free Press; Detroit Historical Society

This article originally appeared on USA TODAY: The Edmund Fitzgerald sank 50 years ago. How big was the ship?

Reporting by Stephen J. Beard, USA TODAY / USA TODAY

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