ob_server I can understand the science behind the guy using a grass cutter and the one at the front paddling the rafter to keep it not rotating
"Boat propellers and grass cutter blades have fundamentally different shapes and designs because they are optimized for moving fluid (water/air) efficiently versus physically severing solid material (grass/weeds). A boat propeller uses a twisted airfoil shape to create thrust, while a grass cutter uses a flat or slightly curved sharp edge to slice or impact vegetation".