Previous Next Surface-Piercing Propellers Even though it seems counterintuitive, surface piercing propellers are the most efficient way to create thrust in the water. A Surface Drive is a drive system which runs the propeller half submerged instead of fully immersed in water. There are many ways to achieve. Our preferred way is: The BPM Surface Drive The Italian BPM surface drive is a derivative of the patented Arneson Surface Drive. Unlike the Arneson, the BPM is designed to only articulate in the vertical plane, which provides a limited range of trim. The degree of articulation is dependent on the length of the hydraulic trim cylinder, but generally less than 15 degrees. The BPM is the lightest, most efficient way to apply torque to a surface-piercing propeller. For this reason, the BPM surface drive has been the drive system of choice for every UIM Class 1 World Champion in the last two decades.