SHARROW PROPS
Sharrow Marine makes waves in the propeller market.
The Sharrow propeller originated in an unlikely setting—a symphony music hall. This is where film producer Greg Sharrow was trying to capture overhead video footage of an orchestra’s performance using a drone. But there was a big problem: The buzzing propellers created excessive noise that interfered with the performance.
Sharrow needed a propeller that eliminated the primary cause of propeller noise: vortexes and cavitation at the blade tips. He racked his brain for a solution. Then, while walking his dog one day, it dawned on him that ribbonlike looping blades would get rid of tips, largely eliminating vortexes and cavitation noise.
Thus, a new propeller design—the loop prop—was conceived. But it took years of engineering, testing and refinement to perfect it and bring it to fruition. Today, the Sharrow Marine design enjoys protection by multiple patents in the United States and overseas.
While the design has found applications in aerospace and commercial shipping, the recreational boating market has become a major focus, says Sharrow, founder and CEO of Sharrow Marine. These are for outboards and sterndrives between 100 and 450 hp in both right- and left-hand rotation configurations.
Boating plans to do its own comparative testing, but in the meantime, the inventor claims a number of advantages. “One of the first things you’re going to notice is a dramatic improvement in handling,” Sharrow reveals. When making a tight turn at speed, the prop refuses to ventilate, he says.
Slow-speed handling also improves, with the boat becoming more responsive to subtle throttle inputs, including reverse. “When you put the boat in reverse, you’re going feel like you have more directional control,” Sharrow reports.
The loop prop also reduces noise, Sharrow says, and he explains that a great deal of engine noise emanates from propeller cavitation. “When the cavitation is gone, the noise is gone.” Onboard sound levels have dropped as much as 5 to 7 decibels in company testing.
Sharrow reports fuel economy gains as high 9 to 15 percent, citing the reduction in vortexes on the blade tips, which create drag and reduce efficiency with conventional propellers.
Boaters fitting Sharrow props can also expect stronger acceleration. “You’re going to be able to get on plane at lower rpm,” Sharrow says, “and you’re going to be able to hold the boat on plane at lower rpm.”
It’s not just about the blade design, Sharrow points out. “It’s how all of the different parameters of the blades work in concert with each other to create the desired performance enhancements,” he explains.
Sharrow also reports speed gains at wide-open throttle of 2.3 to 3.5 mph in on-water tests.
Want to buy a Sharrow? You can go two routes. One is the MX-1S, a CNC-machined, lab-finished stainless-steel model custom-made with the optimal diameter and pitch for your boat and motor. The price is a hefty $5,000 per prop, with a wait time of nine to 12 weeks.
A less-expensive alternative is the MX-1R, an investment-cast stainless-steel version available in diameters ranging from 14.5 to 16 inches, and pitches from 15 to 23 inches. The price is $2,000, with estimated availability in spring 2021. Both versions can be ordered online at sharrowmarine.com and are available with extended protection plans.
Stay tuned for our comparison test in an upcoming issue.