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Going Electric

Yamaha’s Harmo e-outboard debuts in the United States, and boatbuilders are testing the technology.

Yamaha has never been a company to rush anything into production, and its first electric outboard, Harmo (short for harmony), is a prime example. The first iteration of this propulsion system was unveiled in Europe in 2016, and its newest version was officially revealed in the U.S. last September. Its predicted appearance on American boats won’t occur until 2023.


Still, the big-player electric outboard race is officially on, given Brunswick’s recent announcement that it would field five electric propulsion systems by 2023. Already on the market is Vision Marine’s E-Motion 180E (for 180-hp) which I tested at the International BoatBuilders’ Exhibition and Conference. With eight people aboard a 22-foot Starcraft pontoon, it pushed the boat on plane quickly in near silence. With a lighter load, it reportedly reaches a top speed of 31 knots.

While high-power electric outboards are the future, conventional lithium-battery technology isn’t quite ready to supplant fossil fuels as a power source for mainstream boats. So, instead of focusing on large outboards that can rip like a Tesla for half an hour, Yamaha focused on quietude, precise control, smoothness and maneuverability—things the smaller electric outboard can deliver in spades.

Make no mistake; Yamaha isn’t likely to ignore the high-horsepower arena. “As battery technology/efficiency progresses, it will help expand all electric propulsion areas, including larger and higher-output marine products,” says Phillip Speligene, Yamaha’s product planning department manager.

Don’t Call It a Prop

The major diversion point that separates Harmo from other electric outboards is its rim-drive system, which is a technology used in a range of applications, from bow thrusters to ship propulsion.

Rather than using a traditional exposed propeller that pushes a boat in a turbulent froth of power, Harmo employs a 15-inch-diameter, four-blade, aluminum impeller that’s powered by a brushless 3.6-kW motor. Harmo weighs just 121 pounds and produces 225 static pounds of thrust, which is the equivalent of a 9.9-hp gasoline outboard. That type of outboard typically uses a 9¼-inch diameter prop, so the water-moving capability of this Yamaha is significantly higher.

While Harmo resembles a sterndrive, it’s just a very short outboard—it’s self-contained outside the transom. The upper part of the motor is fairly wide, but its housing is mostly a styling façade with not much inside. If the casing conformed to its contents, Harmo would take on a stick-like appearance. It only contains a steering actuator, lower unit supports and an enclosed wiring harness. Its short stature allows it to tilt 74 degrees upward to rise clear of the water and prevent marine growth.


The rim-drive propulsion system works like a bow thruster and pulls water through it rather than pushing water like a normal prop.


Helm Master Control

To enhance maneuverability, the independently articulating lower unit of the Harmo outboard can turn 70 degrees in either direction. By comparison, a Yamaha F9.9 turns 43 degrees each way. With 140 degrees of total articulation, a Harmo helmsman can turn a boat around in a single boat length.

To harness this agility, Harmo can be controlled by Yamaha’s Helm Master joystick in addition to a traditional steering wheel. With twin Harmo outboards, the joystick can be tilted to the right or left to move the boat sideways. The drive-by-wire system allows the operator to make fast, precise corrections that wouldn’t be possible with an outboard and hydraulic steering.


What’s Missing?

The Harmo outboard’s Helm Master control lacks Yamaha’s SetPoint suite of advanced features—for now. Such features include the StayPoint virtual anchoring system, which holds a boat’s position and heading even in wind and current, and FishPoint, which holds the boat’s relative position and allows it to point in whatever direction the wind and current dictate, reducing the number of shifts needed.

Speligene says that installing SetPoint is only a matter of adding hardware, such as a heading sensor, and integrating software. With those changes, Harmo would be a potent fishing weapon, as it would eliminate the clunking sound that even a Yamaha outboard with the Shift Dampener System emits when used as a virtual anchor. And with more range of motion, shifts would be fewer, while control would be even greater.

The system can currently be installed in boats up to 32 feet.

The system can currently be installed in boats up to 32 feet.

Power Choices

Yamaha leaves it up to its vendors to supply their choice of batteries for Harmo’s 48-volt system—a smart move, since battery technology is projected to be in a state of flux for the next few years as new platforms emerge and supply chain disruptions make models tough to obtain. This strategy lets boatbuilders take advantage of whatever technology suits their usage and budget.

There are many ways to get to 48 volts. For example, Yamaha’s electric golf carts use six 8-volt conventional batteries to power them. Several reputable marinized lithium battery solutions are on the market, such as Dakota’s 48-volt lithium iron phosphate marine battery that weighs just 77 pounds and contains 96 amp-hours of stored power. Another solution would be four 12-volt batteries, wired in series, such as the Lithium Blue LiFePO4 (lithium iron phosphate) DLB-GC12 batteries, which have a whopping 200 amp-hours of capacity.

A builder could even use conventional lead-acid batteries, which would be cheaper but would incur a significant weight penalty and can only be discharged to about 50 percent without causing premature aging. By contrast, lithium batteries can be repeatedly discharged fully without harm.

Harmo’s Future

Although Harmo will likely be used as the main propulsion system for boats plying waterways with horsepower or gasoline-power restrictions, at its U.S. unveiling, it was also shown as an auxiliary/trolling motor on a fishing boat. Right now, it is only being used on the Respiro, a 23-foot runabout built by Venmar in Italy. Yamaha has not announced a price for Harmo.

“Harmo is the perfect system for horsepower- or internal-combustion-restricted waterways,” says Ben Speciale, Yamaha Marine U.S. Business Unit president. “Ultimately, it is up to our boatbuilder customers to decide how to integrate it into their boats, and we are eager to see the result.”

This article originally appeared in the February 2022 issue of Power & Motoryacht magazine.