Scout 320 LXF with Twin Yamaha 300 HP – 80% Faster at 3000 RPM
80% FASTER at 3000 RPM
13% MORE FUEL EFFICIENT at 38 MPH
Like most boats in class with twin outboards, the Scout is least efficient—burning the most fuel for a given distance—at the point between running as a low speed displacement hull and being fully on plane.
As the chart shows, the boat begins to “squat” at 2000 rpm, 9.2 mph with the conventional props and 9.7 mph with the Sharrows. By the time the engines reach 2500 rpm, the boat is traveling only 11.0 mph with the conventional propellers, but jumps to 17.0 with the Sharrow propellers—55% better.
Sharrow propellers also show a significant advantage in fuel efficiency at what might be a fast trolling speed between 1500 and 2000 rpm, 8.6 to 9.7 mph with the Sharrows. This is a speed typical in trolling artificial lures for blue water species like wahoo. The Sharrow propellerss peak at 1.31 mpg was 27% better than the conventional propellers in fuel efficiency. Between 3500 and 4000 rpm, the Sharrow propellers delivered 13% better than traditional props.
The Sharrows continue to show an advantage all the way to 4000-4500 rpm, covering the likely cruising speed for this combination. Better fuel efficiency not only cuts boating costs, but also increases the safe range of the boat.
The “advance rate” is the calculated distance propellers push the boat for each revolution. It typically approaches the pitch at wide-open throttle. The tests showed that the Sharrow propellerss came closer to their nominal pitch at all rpm but had the greatest advantage, 80%, at 3000 rpm, where they pushed the boat forward 16.63” per revolution, while the traditional props only advanced 9.24”.
At 4500 RPM the Sharrow props advanced 18.1" for every 360 degree revolution, or were 95% efficient. The optimum blade advancement for the traditional props were 16.72" at 5000 RPM, and were 88% efficient. That percentage is not unusual for old technology props.
In short, Sharrow propellers deliver significantly better speed and fuel efficiency in the low and mid ranges where most boats are run most of the time. Users also report less noise and vibration at speed as well as better control around the docks.
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