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New Ultra-Efficient Propeller

Sharrow's toroidal propeller gets contra-rotating double upgrade.


Sharrow's toroidal propeller gets contra-rotating double upgrade.
Credit: Sharrow Marine

In early 2023, OGN brought you news about strangely-shaped twisted-toroid propellers that were a revolutionary (sorry) advance for the aviation and marine sectors. Radically quieter than traditional propellers in both air and water, they're also showing some huge efficiency gains.


Even though Sharrow's extraordinary toroidal propellers were already some 30 percent more efficient than traditional designs - the company has now put two of them together into a coaxial, contra-rotating propeller that promises to be even more energy-efficient.


The new Sharrow CX incorporates the company's toroidal design into a contra-rotating propeller set. The sculptural new prop doubles up on looped blades with the promise of bringing Sharrow's efficiency-boosting, noise-cutting benefits to the already efficient world of contra-rotating outboards and sterndrives from top names like Volvo and Mercury.


The contra-rotating propeller is a fairly simple concept that features two propellers rotating in opposite directions around the same shaft. The independent and opposite rotations counter the energy otherwise lost in tangential flow, better focusing it on the thrust that drives the boat. The drive system then runs more efficiently than a comparable single-prop drive, resulting in a vessel with improved acceleration and speed, better fuel efficiency or a combination of both. Volvo also claims handling and tracking improvements.


Beyond a general promise of better efficiency, agility and manoeuvrability, Sharrow doesn't dig too deep into how its toroidal blades might improve upon the benefits already inherent in contra-rotating propulsion. It will definitely be interesting to hear results from the water as to how the two fare together, though. OGN will keep you posted.

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