Arneson surface drives are a specialized marine propulsion system designed for high-performance boats, utilizing a surface-piercing propeller where only the lower half of the propeller blades submerges in the water while the upper half operates in the air-water mixture created by the boat's hull. Unlike traditional inboard-outboard stern drives or submerged propellers that generate massive drag from underwater gearcases and shafts, Arneson drives mount the propeller shaft straight through the transom, utilizing a universal joint system that allows the entire thrust unit to articulate side-to-side for steering and up-and-down for trim control. By minimizing underwater hydrodynamic drag, these drives allow boats to achieve significantly higher top speeds, superior propeller efficiency, and incredible directional stability at high operational velocities across open ocean waters.