Flux Marine’s Electric Outboard Advances Propulsion Innovation

The Flux-powered Highfield 660 offered a smooth, silent ride. Courtesy Flux Marine

Flux Marine co-founders Ben Sorkin, Daylin Frantin and Jon Lord say that they began developing an electric outboard ­motor in a garage. That’s a startup plan that worked out for Bill ­Harley and Arthur Davidson, and famously for Bill Hewlett and ­David Packard. It’s too early to tell if Flux ­Marine will scale similar heights of market success, but after 10 years of research and ­development and a claimed investment of $30 million, the founding trio has expanded to 50 employees, the garage has been replaced with a 40,000-square-foot manufacturing facility in Bristol, Rhode Island, and the sleek and sophisticated Flux ­Marine electric ­outboard is in production.

Sorkin started tinkering with electric power for small hydroplane boats while studying mechanical and aerospace ­engineering at Princeton ­University, from which he graduated in 2017. He spent time at Tesla and designing electric propulsion systems for the office of Naval Research before devoting his full attention to the startup.

The completely completely closed system does not require maintenance or winterization. Courtesy Flux Marine

“The idea behind Flux Marine was that there has to be a better, more-sustainable way to power a boat. We are not trying to do something so radically different that it alienates people,” Sorkin says. “We are trying to do something that evokes excitement and offers innovation but still makes you feel comfortable with what’s powering your boat.”

The Flux Marine outboard went into production in late 2024, and the company is currently providing an OEM propulsion system for the Scout 215 Dorado, the Scout 215 XSF and the Highfield Sport 660. The company also offers the Flux outboard paired with a 24-foot pontoon it sells directly.

Every component of the Flux Marine outboard was designed in-house, according to Sorkin, in an effort to optimize affordability, safety and performance. Sorkin reveals that the system underwent field testing aboard boats from 2022 to 2024, and recently survived 1,300 hours at wide-open throttle in a test tank, with no maintenance issues. The production motors and battery system are all assembled by Flux. A five-year standard warranty covers the Flux drivetrain and the battery pack that powers it.

The charging port below a hatch in the cowl accepts a Level 1, Level 2 or Level 3 connection. Courtesy Flux Marine

The outboard is rated at 100 hp sustained and, for bursts of acceleration, 150 peak horsepower. It weighs about 325 pounds. ­Energy is provided by a modular system comprised of three 400-volt 28 kWh batteries, for a total of 84 kWh of storage. Each battery weighs 325 pounds, so the entire system weighs roughly 1,300 pounds. By comparison, it’s about 750 pounds for a 150 hp internal combustion motor, 37 gallons of gas in the Highfield 660, plus a starting and house battery. The charging port below a hatch in the cowl accepts a Level 1, Level 2 or Level 3 connection, so when trailered, it can be plugged into an EV-charging station.

Because it is always working under heavy load when pushing a boat—just as an internal combustion engine must—cooling the motor and inverter is a challenge for an electric motor. Flux was determined to design a cooling system that does not rely on seawater, and so created a system that circulates a glycol solution around the motor and inverter and through passages in the ­aluminum antiventilation plate, which acts as a heat exchanger. This completely closed system does not require maintenance or winterization. There is no need to flush the motor internally after use in salt water, but an exterior wash with fresh water would be advised, as with any outboard.

Read Next: The Differences Between Radial, Axial and Transverse Flux Motors

A belt-driven propeller allows for a flow-through lower unit that reduces drag and feeds more and cleaner water to the prop. Courtesy Flux Marine

Another compelling design element of the Flux outboard is its midsection and lower unit. ­Because the outboard does not need an exhaust outlet or ­forward/reverse gears, the Flux team was able to reimagine transfer of power from the motor to the propeller. Flux drives the prop with a 4-inch-wide synchronous belt. The typical midsection is replaced with a “dual strut” ­design that surrounds the belt but is open in the center. This both reduces drag and improves water flow to the propeller.

The Flux outboard powered a 21-foot-10-inch Highfield 660 Sport—a RIB with an aluminum hull—for our short test runs in Michigan. The motor propelled this very light boat from zero to 30 mph in 8.1 seconds, en route to reaching a top speed of 31 mph. The boat heeled over on its inside tube and carved neat turns, and the prop stayed hooked up. The motor would tilt out of the water. Cruising at 21 mph, the display indicated a range of 32 miles while drawing 56 kW, or about 1.5 hours of use. The controls are smooth, and the motor is essentially silent.

This fits the use case of Steve Eddleston, owner of the historic 12-Metre racing yacht Weatherly, berthed in Newport, Rhode Island. Eddleston purchased a Flux-powered Highfield 660 as a tender to commute a 25-mile round trip by water from Bristol to Newport.

“I hate fumes and pollution,” Eddleston says. “This boat has the range I need, great stability and handling with the battery weight low and forward, and I can bump right up to Weatherly. I return to dock in the evening and plug into shore power, and it charges overnight. No gas dock. It’s ­harmonious with my life.”

The Flux-powered Highfield 660 has an MSRP of $110,000, compared with about $83,000 with a 150 hp gas outboard. It will be fun to see how far the young ­entrepreneurs at Flux can fly.

Speed, Efficiency, Operation Flux Marine Outboard Certified Test Results Boating Magazine

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