Aimed at shaft-driven boats, this unique system delivers faster acceleration, higher top speeds, better fuel consumption and reduced vibration. The Duodrive system provides a methodology for improving motorboat performance by combining sterndrive performance with shaft drive installations. This technology gives a method of creating counter-rotating output from a single input and is designed to be both retrofitable and factory fit. Owners of existing shaft driven craft too can benefit from the significant efficiency improvements brought about by this invention.

The Duodrive system brings significant efficiency improvements. Counter-rotating propellers eliminate waste. In this type of installation, two propellers are positioned one immediately ahead of the other on the same shaft line, but rotating in opposite directions. The rotational energy imparted to the water by the forward of the two propellers is cancelled out by the opposite rotation of the rearward propeller. The slipstream from counter-rotating propellers is almost smooth and straight, with little twist. When a single propeller accelerates water into itself from ahead and expels it astern, it generates thrust like a jet engine. Unfortunately, a significant percentage of the power delivered to the propeller also goes into twisting the water around, creating the helically-shaped propeller wake. This energy is exhausted and does nothing in providing propulsion, or drive; it is, simply, wasted. Duodrive's concept of counter-rotating propellers aims at dramatically reducing this waster effect and is expected to be 15 to 40 per cent, dependant upon configuration, more efficient than standard, single propeller sets.

The Duodrive product is a self-contained, maintainable sealed mechanism initially intended for the marine leisure industry. It is designed to slot in between a recipient craft's gearbox output shaft and its driveshaft through-hull gland. After substituting the recipient craft's driveshaft with a shorter dual shaft arrangement, the Duodrive system slots into place.

Benefits resulting from the introduction of this new technology are significantly increased efficiencies through performance gains, reduced operating costs and environment improvements.