The Q-SPD SD series is now the most popular of all Q-SPD drive models. It began life as the ideal alternative to stern legs offering a virtually maintenance free solution to the worlds most maintained propulsion system, stern legs. In addition to low maintenance, the SD Drive has the ability to transmit a lot more engine power than most commercially available stern legs. Today, the Q-SPD SD Series is available in three base models for power options from 200hp to over 1200hp. Due to the advanced propeller design, a unique ventilation system, integral thrust bearing and the evolution of the unique twin side rudders, Q-SPD SD Drives are smoother and quieter than any other surface drive. In fact, reports claim smoother than conventional, yet they offer all the performance advantages of a ventilated propeller. The methods of composite manufacture used ensure the SD Drive is about half the weight of most other surface drives, and just as, or more, robust. The twin rudders also offer better tracking, steering and maneuverability at all speeds.