A bit off topic, but this thread started me surfing the web to read about the Edmund Fitzgerald. A couple things are puzzle me.

Web sites describe the Fitz as an iron ore carrier. Does a bulk carrier like the Fitz carry just one kind of cargo? If not, what cargo would she carry on the return trip? The American Steamship Company site lists iron ore pellets, limestone aggregate, eastern coal, and western coal as cargo. Seems like there would be a limited need for limestone aggregate at the mines and, besides, the tonnage they list for limestone is only a fraction of the tonnage for iron ore. Carrying eastern coal to the source of western coal seems pointless. Making the return trip in ballast without a cargo is an option, I suppose.

Does overloading a bulk carrier like the Fitz make sense? The ships are designed to always make the same trip through the Soo locks, the St. Clair and Detroit Rivers, and to dock broadside – fully loaded and without bottoming out. If you overload the ship you run the risk of drawing more water than the locks, channels, and ports allow. It's also not clear where you would put extra cargo once the ship is fully loaded, assuming the ship is designed to travel fully loaded on each trip anyway.

It also seems curious that bulk coal carriers are oil-fired, but there must be strong economic and/or environmental reasons. Otherwise they'd all be coal-fired.

Pardon the thread drift and my ignorance about this topic. The Great Lakes are a long way from the southern Great Plains where I'm sitting this morning.
- Phil