Does thumping work on rivers when the sand bass are running?

I don't think that matters. They are already in a confined area and that is the idea behind thumping to group the fish up.

This^^^^
Besides if it is as crowded as everyone on here says, you might make some enemies thumping that close.
If alone for a long stretch and not catching I might try it though.

I figured if thumping worked on the river I could possibly save the entire sand bass population from extinction...and help you aggressive, social media fame seekers keep good moral character...here's the plan...When ever I see a group of boats catching sand bass I can start thumping and lead the poor unsuspecting sand bass to a safer place...Hahaha...what do you think.

That might be good for the sandbass but probably not so good for you.

yeah, I love the smell of gunpowder in the morning!