Sergeant John Hamilton said police issued six infringements in just over an hour for drivers crossing the centre line on State Highway 1 over the Hundalee mountain range.
This included the driver with the boat who was seen "with all four wheels of their vehicle on the opposite side of the road, as they went around a corner".
Sgt Hamilton said it was "incredibly frustrating" that they were catching so many drivers who were risking their own lives and those of other motorists.
"This is how head-on collisions occur, especially on or near corners where motorists have less time to react."
He said police would continue to target such behaviour.