Being old enough to remember the Fess Parker "Davy Crockett" movies, I recall scenes where Davy was on a keel boat(?) that was propelled by men walking the length of the boat, from bow to stern, with long wooden poles that were long enough to reach the river bottom so that as they pushed against the pole while walking the length of the boat, it pushed the boat forward.

In that regard, "beach" (or river bottom near enough to shore for the poles to reach the river bed) might make more sense than naming the wood which those poles were made of. As far as an "oar" goes, that might not necessarily have to be what we might think of as a wooden pole with a flat blade that pushes against water, not the river bed.

More like such, maybe: https://youtu.be/WYRtziLzSjQ 'Course, that's presuming Hollywood got it right for river boat propelling of that period.