The Perils of Great Lakes Shipping

I was aware of the cresting failure mode below. Now I know of other ways that waves can damage a ship. Note that the stress on a ship goes up as the height-to-length ratio of the waves goes up. I knew that the height-to-length ratio was higher on the Great Lakes than on the open oceans. But I still don't understand why. The comments agree the reason is not fresh water vs. salt water. It is because the lakes are smaller than the ocean. But I still don't understand why a smaller body of water shortens the wavelength of high waves.

Diagrams prepared by Jonathan Devine, 2019, Licensed: Creative Commons Attribution-ShareAlike (CC BY-SA)

1

2

3

4

5
Brucedaniel Chalupsky Assumes a great lakes wave roughly 1.5x the height of the hull, and the wavelength 1.2x the hull length. No recorded wave on the GL has been larger than 40' (Pore, 1970) even in max wave scenarios modeled by NOAA show a rouge to be approx 45 feet.

6

Port Huron Museums posted the diagrams with the comment:

Many people ask about how and why so many ships have sank on the Great Lakes. This is an illustrated guide by Johnathan Devine to just some of the perils one of the large vessels face on the Lakes, especially in major storms. To find out more about the aftermath of the biggest storm of all in 1913, stop by our ongoing exhibit "Diving for Answers" at the Carnegie Center. Open Wednesday-Sunday, 10-5.

Rick Aylsworth They missed one important phenomenon, that of shifting cargo. When the ship rolls far enough, loose cargo like ore or grain can shift to one side and not shift back. That affects how the ship handles and makes it more prone to capsize.
Andrew Haenisch shared
Bill Shaver thats why they are designed to flex...
Terri Moore People would be surprised how MUCH they flex. Stand at one end of the tunnel, and the lights at the other end appear and disappear.
Jim Nemecky Just stand up in the wheel house and look aft during a storm! You'll see the give of the vessel or when walking through the hatches catwalks you can hear and feel the ship's give as she sings high pitched cries or look at the ingots shift.

Per the comments, the following three photos are a sequence of three photos taken by Frederick Vieau Jr. - Oiler, circa 1931.

1
AmericanHistory
reddit
Ore boat William H. Truesdale weathering a violent storm on Lake Erie, 1930s
Eric Pieper shared
Darren Hilts: In their defense most deckhands were extremely young in those days and hadn't learned that the old guys were lying when they told them that it was safe.
Carl Sundbeck: Darren Hilts But days like this are infrequent.
Darren Hilts: Carl Sundbeck Now, but before satalite weather modeling it wasn't as infrequent as you'd like.
Andy Eckroth: No tunnels, either. Want to go from one end to the other? You can see the lifeline in the photo.
Ed Hughlett: Andy Eckroth I had the opportunity to use a life line on a few occasions to go aft to the gallery for a bite of food : Kinsman Enterprise October/November 1966.
Irene Vieau: The engineers from my remembrance, were busy keeping the pumps running. Pumping out water when their was high seas.
Corey Hurst: That's one of my favorite things about the old freighters. You were basically out there in a heavily laden canoe. I love looking at the pictures and imagining how bare bones all those old ships were and what they accomplished back then with next to nothing.

2
nemoha, cropped
William H. Truesdale was built in 1908

3
pinterest