Surface-Piercing Propellers
Even though it seems counterintuitive, surface piercing propellers are the most efficient way for high speed vessels 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 this. 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 stroke of the hydraulic trim cylinder, but is generally less than 15 degrees.
The BPM drive cannot be steered, so a boat requires one or more rudders.
Efficiency
The BPM is the lightest, most efficient way to apply torque to a surface-piercing propeller. For this reason, this surface drive has been the drive system of choice for every UIM Class 1 World Champion in the last two decades.