Last weekend I watched a joy rider run the Meramec with a big jet, 200 HP or so. It didn’t appear the gentlemen made any attempt to read the river or select a path based on conditions, he simply ran straight down the middle and throttled up when he encountered shallow water. Judging from the chocolate water and the rocks shooting from the wake his boot and impeller got a good shine.
We ran up the river in our 21ft glass river jon, 450lbs of fishermen, ~300lbs of gear and camping luxury powered by a 20HP jet and never ate a rock.
You definitely don’t need big power as much as you need your eyes and a little sense.