The white people had a small pontoon boat, and they were blocking the dock, but the bigger boat ride everyone was on needed to dock there so one of the employees asked them to move out of the way so they could dock.
Instead of moving they got mad, probably because they were all drunk as skunks and decided to attack him for some reason and then ganged up on him out of nowhere and then a bunch of black people on the other boat and around saw it and came to his rescue before the cops show up