A great question Mark best answered by the Man himself from
the Songbook booklet as archived at:-
http://web.archive.org/web/199910131...75802lin5.html
"The inspiration was a Newsweek article about the wreck. These sorts of things have happened on the Great Lakes for many years, and I thought I had another shipwreck song in me after having done "Marie Christine" years before. I'm proud it's been written. It's been a very educational and interesting experience, for sure. I have gotten to meet a lot of the people who were related to the men on the Edmund Fitzgerald; periodically they have functions, which I attend whenever I can. It's been a real-life experience for me."
the story obviously appealed to Gord
I see that you are a student in a wet area

Bishop's Falls, New Found Land January 1983
Give it time to load and "animate"
John Fowles