A Cleaner Vision for Fun

Jack Duffy-Protentis ’20 stood waist deep in the glistening waters of Lake Winnipesaukee, trying to hold a five-gallon gas can steady over a Jet Ski bobbing in the waves.

Droplets of fuel rolled into the water despite his best efforts, spiraling out in brilliant toxic rainbows. Fed by thousands of other such refueling attempts, a thick band of sludge and trash lined the shoreline around him. While there are few things the teenaged Duffy-Protentis liked more than a day on the water, he recognized that this gas-powered watercraft he adored was threatening the very resource it relied on.

At that moment, Duffy-Protentis decided he would one day tackle the challenge of creating a cleaner Jet Ski. But this wasn’t the only challenge he faced. At age 8, he was diagnosed with Stargardt disease, a degenerative eye condition that would eventually render him legally blind. His visual impairment had the potential to make his goal daunting, if not impossible. But “impossible” is not a word Duffy-Protentis readily accepts.

Each year, more than a million registered Jet Skis take to the water in the United States, emitting up to 300 pounds of carbon dioxide per hour of operation. Older two-stroke engines compound the problem—by some estimates, nearly 25% of the engine’s fuel leaks directly into the water unburned. For enthusiasts like Duffy-Protentis, the solution isn’t abandoning the sport. It’s engineering a better way forward for the environment and users alike.

With his experience on Lake Winnipesaukee in mind, Duffy-Protentis first tackled the challenge of polluting watercraft as a mechanical engineering student at WPI. “Tesla really started to boom in 2018,” he recalls. “And I started thinking, why couldn’t a Jet Ski also be adapted for cleaner recreation?”

This epiphany led to Duffy-Protentis’ Major Qualifying Project (MQP), where he and his team used a 10-horsepower golf cart motor and batteries from a Nissan Leaf to flesh out the concept behind a fully battery-powered Jet Ski. Despite making admirable progress, Duffy-Protentis found himself far from the fully electrified watercraft he envisioned. After graduating in 2020, he couldn’t shake the feeling he’d left something important undone. “I was just getting into the job market, but nothing piqued my interest as much as working on my MQP,” he explains. “No one was making an electric Jet Ski at the time and I thought, man, this could really be something.” Less than a year after graduating from WPI, Duffy-Protentis founded eSki Watercraft and began onboarding employees at his first facility in Worcester.

ESki’s electrical and mechanical team spent the first year and a half on research and design. In crafting the Jet Ski Duffy-Protentis felt the public would embrace, he took a cautionary note from Tesla’s Cybertruck, which debuted to mixed reviews.

“It looks cool,” he admits of the Cybertruck’s radical design, “but in an attempt to make it feel new, it turned people off because it didn’t look like a vehicle they were used to.” The eSki team aimed to strike a balance between the new and the familiar—while recognizably a Jet Ski in its proportions and stance, their concept was sleeker and cleaner without the bulk of a gas engine. The team hoped the craft’s familiar silhouette would reassure riders, while the refined lines hinted at the electric innovation within.

Their efforts culminated in a meeting Duffy-Protentis will not soon forget. “Our team pulled up the Jet Ski body in CAD (computer-aided design) and this thing that had only been in my head was suddenly a reality,” he says. “Instead of saying, ‘The width of the handlebars would be about this big,’ we now had it down to a hundred-thousandth of an inch.”

“The industry is dictated by consumers, but dominated by rentals,” he realized, and that represented an opportunity. In February 2022, the eSki team debuted its concept model at the Miami International Boat Show, targeting the rental market. That attention generated momentum for the next milestone—building a fully functional prototype.

The following March, the team guided their first prototype into the frigid waters of Lake Quinsigamond, just a few miles from WPI. Five years after identifying the environmental impact Jet Skis and other gas-powered watercraft were having on Lake Winnipesaukee, Duffy-Protentis dream of an electric Jet Ski was coming to life. And despite being legally blind since childhood, there was no question whether eSki’s CEO would take it for a spin. In fact, if you think this innovator would hesitate to test his own creation, you simply don’t know Jack Duffy-Protentis.

Duffy-Protentis’ mechanical aptitude emerged early in life. At the age of 10, he pressed his father to let him rebuild the 1964 Mustang sitting in the garage—a project that took on special meaning given that two years prior Duffy-Protentis had received his diagnosis of Stargardt disease. This rare genetic condition gradually destroys central vision while leaving some peripheral sight intact. Despite the devastating news, Duffy-Protentis now sees a silver lining in receiving his diagnosis at such an early age. Too young to understand limitations, he approached the Mustang restoration with unshakeable confidence. “In my head, I was building the car I’d eventually drive to high school,” he recalls.

The ability to adapt has served Duffy-Protentis well as a mechanical engineer, but also in persevering in the recreational hobbies he loves. Before taking out his ATV, he first scouts trails on foot, memorizing obstacles and terrain features. He then drives the route slowly, building familiarity until he can confidently increase his speed. Snowmobiling requires a different strategy: Using motorcycle intercoms, he relies on the guidance of fellow riders to alert him to obstacles or sudden turns. Boating demands yet another system, as he and his companions communicate with clock positions to navigate safely. “They’ll let me know, ‘Hey, there’s a boat coming from two o’clock and a buoy at ten-thirty,’” he explains. “So I’ll turn to eleven-thirty, just to be safe.”

Adapting to considerable challenges as a child gave Duffy-Protentis an unshakeable sense of personal agency and the belief that very few tasks are beyond his reach. “I’m a stubborn person,” he admits. “I’ve always had the attitude that I can do whatever I want to—I just have to find my own path.”

The skills that enabled Duffy-Protentis to restore a Mustang as a child, adapt his recreational hobbies, and build a partnership with Adonis would prove essential as he faced his biggest challenge yet: bringing an electric Jet Ski to market.

On that cold morning in 2023, Duffy-Protentis zipped up his wet suit and waded through Lake Quinsigamond’s icy waters to eSki’s first fully functional prototype. He climbed aboard, and with one twist of the throttle felt years of problem-solving surge to life. “We’d been working on this thing for so long, and it was everything I knew it would be,” he recalls. As he expected, the Jet Ski delivered the instant torque unique to electric vehicles, pressing him back in his seat with blistering acceleration. And it did so in remarkable quiet.

“Normally with a Jet Ski, all you hear is the engine going, but because the eSki is battery powered, you can hear birds chirping and cars going by on the highway. It makes you feel a lot more connected to the waterway.” Skipping across the lake surface, Duffy-Protentis had proof of concept that exceeded his expectations. Now came the harder challenge: persuading customers they needed his invention.

As Duffy-Protentis pitched rental operators, he discovered that an environmental message that once started conversations was now falling flat. “I started hearing, ‘I get it. It’s electric, it’s clean, but what else?’” Recognizing a growing cultural backlash against electric vehicles, he pivoted to emphasizing economics instead. An eSki’s charging costs are around $1.37 per hour compared to $60–70 a tank for gas-powered Jet Skis, maintenance requirements are dramatically lower, and the watercraft lasts more than twice as long—over 1,000 hours compared to 250–500 for gas-powered models.

Having honed his message, Duffy-Protentis encountered a new objection from his target audience: charging downtime. Rental companies balked at the idea of having half their Jet Skis out of commission while they recharge. “If you’re a rental company in New England, you’ve got a four-month season—and you need your Jet Skis on the water eight hours a day, five days a week,” he explains. “You can’t afford to cut your available fleet in half while they charge.”

After a week of visiting rental operations along the Florida coast, he secured 125 letters of intent—nonbinding purchase commitments—bringing eSki halfway to its goal of 250 orders in the first year of production. That interest brought them one step closer toward the manufacturing phase. Now based at Greentown Labs, a climate tech incubator outside Boston, eSki has built a network of supporters. The company was named a 2025 Eddie finalist by the Massachusetts Innovation Network, connecting Duffy-Protentis with seasoned mentors and potential investors. He also credits the Berkshire Innovation Center with connecting eSki to Western Massachusetts manufacturers who can handle fabrication and other hardware needs.

With strong market validation and a growing ecosystem of support, Duffy-Protentis is now raising funds to take eSki from prototype to full production in 18 months. If successful, rental fleets across Florida—and beyond—could be running on electric power within two years. But Duffy-Protentis is already envisioning his company’s next move: an entire family of recreational vehicles built around the same hot-swappable battery technology. “I’d love to have the eSki, the eSled, and the eDirt Bike,” he explains. “When you’re done with your Jet Ski for the season, just throw the batteries in your snowmobile.”

Duffy-Protentis’ refusal to accept limitations runs from his childhood diagnosis through his current role as CEO—and the throughline isn’t lost on him. “Being visually impaired forced me to develop problem-solving skills very related to engineering and entrepreneurism,” he says. “Whether as a teenager figuring out how to get to my friend’s house when I can’t drive or as a CEO starting a business, it’s all the same skills.”

Yet as his company gains recognition, Duffy-Protentis has noticed a welcome change in how others respond to his story. “Being blind is certainly part of my story, but it’s nice to see the narrative shift from, ‘Look at this blind person doing something cool,’ to ‘Look at how impressive this idea is,’” he explains. “That shows that the pillars of me, the company, and the idea are strong enough to stand on their own.” After a lifetime spent redefining what is possible, Duffy-Protentis is just getting started—and the world’s waterways may never be the same.

For more information about eSki and possible investment opportunities, contact Duffy-Protentis: jack.duffyprotentis@eskipro.com.