Fixing the motor? Noodling? What was he doing?
The diver was "Musseling" and when he was hanging onto the side of the boat he was measuring the mussels he had harvested from the lake. As we watch him, we could see he was throwing back some of his harvest.
He was in Tennessee waters and evidently knew the rules
and how to identify the mussels. I don't know if he was a commercial mussel harvester or perhaps an employee of the Tennessee Wildlife Resources Agency doing research.
I thought it rather foolish for him to be doing the diving, depending on the "lawnmower" motor to provide his air, without another person in the boat.
Commercial Musseling used to be a big time business in the area of the Tennessee River, as we learned on a later visit to the Nathan Bedford Forrest State Park where there is a nice display on the subject.