‘Mark twain! Safe water!’ was the call that riverboat pilots liked to hear. If a depth of 12 feet was safe, what was the draft of Mississippi riverboats?
Typically less than a man so I guess 5 to 6 feet max.
Riverboats had very shallow drafts. That was a design feature.
Of course, different boats are different but as an example this one had a draft of 22 inches (although this one is a small riverboat). (70 tons)
This wiki page says the riverboat Washington had a draft of 4 feet (1.2m).
Further down that page it notes a riverboat with a 6-foot draft. (1384 tons)
I’d be surprised if they got much more than that.
The Albatross, a steel-hulled side-wheeler originally built to transport railroad trains across the Mississippi River before a bridge was built at Vicksburg, had a draft of only 7.6 feet. To this day, river channels are maintained at a minimum of nine feet.
The first channel project was 4 foot, then 4.5, then 6 and finally 9
https://www.nps.gov/parkhistory/online_books/rmr/2/chap1.htm
Brian
Mark Twain wrote of ribermen swapping tales, and one spoke of a riverboat with such a shallow draft, “it could float on a cryin’ woman’s tears.” The tale went on, IIRC, to tell of the boat fetched up on a sand bar, and they brought the weeper aboard to float it off…