How to Choose the Best Propeller for Your Boat

The new props were a side project to their real job creating an entirely new form of silent aircraft propulsion using an ion drive. That's why engineers like Tommy Sebastian, a senior staffer at MIT Lincoln Laboratory, are tinkering with unconventional propeller shapes. New loop-based models are designed to not only reduce noise pollution and help protect marine life but also increase energy efficiency — a win-win-win for the oceans, the climate, and the shipping industry. The result is an incredible reduction in noise, reaching a frequency of 1-5Hz, making the drone’s flying motion sound like a distant woosh rather than a nagging buzz. And the reason behind that is the unusual twisting design that spreads vortices.

Volvo Penta Propellers

Whether you are producing a hero prop, color correct art, or retooling your logo, DesignTown USA will create the perfect design for your message. Because in our high tech world today where CGI is used so often, the use of high-quality, attention-grabbing props are even more effective than ever in getting the consumer to take notice. Pitch is calculated by the theory that if a 12 pitch propeller is moving through a solid structure, one revolution—or turn—of the propeller will move it forward 12 inches.

Looped propellers: A noise-killing game changer in air and water

To reduce emissions, cargo ships have to switch to low-emission fuel sources like green methanol. That would involve redesigning new ships, retrofitting old ones, and building the coastal infrastructure to refuel them. He said that Sharrow Marine produces up to 1,300 propellers a month at its facilities in Detroit and that the company had months' worth of back orders to catch up on through a supply collaboration with Yamaha. His plan is to scale up to make hundreds of thousands of propellers each year. "You can get quite a substantial hum of all those propellers that can potentially cover up that natural noise," Halpern said. Indeed, the company says this is a propeller you can stick on more or less any outboard motor, then blast along at 30 mph (48 km/h) quietly enough to have a conversation on board without raising your voice.

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"The key thing that we thought was making the propellers quieter, was the fact that you're now distributing the vortices that are being generated by the propeller across the whole shape of it, instead of just at the tip," says Sebastian. "Which then makes it effectively dissipate faster in the atmosphere. That vortex doesn't propagate as far, so you're less likely to hear it." The tests were carried out on a 20ft Bayliner VR5 sportsboat fitted with a standard Mercury 150hp outboard engine, comparing Sharrow’s new tipless MX-1 against two market leading boat propellers. The Sharrow Propeller™ is the first major advancement in propeller technology since the 1830s. Specifically, tip cavitation and vortices have been eliminated or significantly reduced, transforming your entire boating experience.

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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. However, extensive sea trials carried out by US website boattest.com on the new Sharrow Propeller MX-1 seem to confirm all of the above and show efficiency gains of between 9-15% over comparable 3-blade propeller designs. The result is a closed loop design that looks like a couple of opposed inclined boomerangs joined at the tips.

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Since then it has already won an award for innovation and the company says it is now in discussion with a number of major propeller and engine manufacturers. He wanted to use camera drones to film performers in action but soon found that their microphones would pick up the noise of the drones. He realised that most of this noise was not being created by the drone’s tiny electric motors but by the propeller tip vortices. And remember, many times there can be 2 propellers that do the same job, but look different and have different dimensions. Your neighbor may have the same boat/engine combo with a different propeller, but that doesn’t necessarily mean that you have the wrong one. Most service technicians at your dealership will be able to discuss propeller options and how they will affect your specific boat.

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Reducing underwater noise could go hand in hand with that transformation. Sharrow hopes to expand into the shipping industry as his company scales up manufacturing. "A ship traveling from Tokyo to Shanghai is going to have direct sound impacts in that area but could potentially send noise all the way across the ocean to Los Angeles," Ben Halpern, a marine ecologist at the University of California, Santa Barbara, told Insider.

Provides Up to 30% Greater Range

Researcher Dr. Tom Sebastian told New Atlas the prop design was inspired by some obscure “ring wing” aircraft prototyped in the early 20th century. He’s not even sure why they work but theorized their odd shape greatly reduces the noise-creating vortices that come off the tips of regular props. Though loop propellers aren't widely used for commercial shipping vessels — the main culprits of underwater noise from propellers — they could one day replace those ships' noisy screw propellers or traditional blade propellers.

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Sharrow's props simply don't create tip vortices – a major source of energy loss and a surprisingly large component in the overall noise of an outboard engine. Improving fuel efficiency is considered as one of the most effective ways to reduce a vessel’s operating costs and fuel consumption. The new Wärtsilä propeller design is considered an energy-saving technology reducing also emissions and improving CII rating. He said they haven’t spent much time optimizing the design but it shows promise, particularly for eVTOLs and drones.

By decreasing and even eliminating tip cavitation and vortices, the Sharrow models also dramatically reduce noise and energy loss when a boat cruises through open waters. Additional benefits include 50% more reverse thrust, 30% more range, less vibration, and doubled speed at mid-range RPMs. Putting its products to the test, Sharrow demonstrates in the below video the dramatic difference in noise production between a standard propeller and its toroidal design. Sharrow Marine has been getting frankly spectacular results from boat propellers that use loops instead of standard blades. After several years of development, the company has now tested its props against hundreds of standard propellers, and the difference is incredible.

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They regularly double the speed a boat can achieve at lower and mid-range RPMs, radically broadening the effective rev range of the motor. And they reduce fuel consumption by somewhere around 20% – a seriously big deal given the huge energy requirements of propeller-driven boats and the scale of the industry. As if it wasn’t already hard enough to choose the best propeller for your fishing boat, a company called Sharrow Marine has developed a completely different kind of prop. Basic propeller design hasn’t changed in close to a century—until now—with what might best be called a “loop” propeller. Essentially, rather than having blades that grip the water to provide thrust, it has metal loops on its hub.

What’s going on here is an attempt to eliminate the cavitation and vortices created by “normal” propellers at the blade tips. Do so, and you should see speed and efficiency boosts plus a drop in vibration. By creating a propeller with the blades replaced by loops, there are essentially no tips whatsoever. These swirling pockets of turbulence are caused by high-pressure air on one side of the blade rushing round to meet the low pressure air on the other, creating induced drag, noise and vibration.

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Within a few attempts, the team indeed found a design that reduced not only overall noise levels at a given thrust level, but particularly noise in the 1-5 kHz range. Third-party testing has shown an overall nine- to 15-percent efficiency advantage, higher top-end speeds reduced vibration levels, reduced sound levels, and enhanced handling. On the plus side, only $100 of that is due on preorder and deliveries won't begin until Spring 2026 (Northern Hemisphere), leaving plenty of time to ponder that additional $8895+.

The traditional method of selecting a propeller takes the horsepower, boat weight, and hull type into account. Then the pitch and diameter are selected that allow the engine to run at the top end of the RPM range. Although propeller theory is straightforward, there are a few variables behind what makes it spin. Our passion for perfection is what drives us to design and manufacture performance propellers to the highest quality standards.