David Borton is on a mission to make solar-electric boats mainstream. The Solaris, the first-ever Coast Guard–approved solar boat, offers a window into his vision.
By Dan McCarthy
5 December 2023
A long, narrow, open-sided boat docked on a river. The name SOLARIS is emblazoned on its back panel.
Solaris and its 6-kilowatt array of solar panels take in a sunny Hudson Valley day. (David Borton/Solar Sal)
KINGSTON, New York — Behind the diesel-powered Rip Van Winkle party boat, across from Mathilda, the decommissioned 19th-century tugboat, and about 1,000 yards upriver from the rusted husk of a retired New York City hospital barge named the Lila Acheson Wallace, you will find the Solaris, pitching softly on the placid Rondout Creek, a tributary of the Hudson River.
It’s an elegant boat, white and cream-colored with wooden accents, its spotless 45-foot hull a stark contrast to some of the older vessels surrounding it at the Hudson River Maritime Museum, where it was built and has ben docked since 2018. But the Solaris stands out for another reason, too: the shimmering solar panels that adorn its roof.
Unlike most boats, the Solaris does not have a gas-powered engine. Nor does it have the ability to plug into a charging station and replenish its batteries. Instead, it gets all of its energy from a 6-kilowatt array of solar panels and 32 lead-acid batteries, a combination powerful enough to propel the boat 100 miles downriver to New York City without a second thought.
The Solaris is the first Coast Guard–approved solar-electric boat in the nation, and that approval means that it is allowed to operate commercially. Dozens of times each week between May and October, it carries up to 24 people at a time on historical and environmental tours of the Hudson River and the Rondout Creek tributary.
But David Borton, the boat’s creator, has a much more ambitious vision for solar-powered boats.
“My goal…is to replace every fossil boat with a solar-electric boat,” Borton aid with a laugh. “Now that’s a ridiculous goal because that’s not going to happen, but that’s the direction that we are moving in.”
It’s certainly an unconventional view.
Ships, boats and other marine vessels are a major source of air pollution and planet-warming carbon dioxide emissions. Thanks to prodding from policymakers, the private sector is starting to take steps to limit both. Larger ships, like those that haul 90 percent of the world’s goods and account for most maritime CO2 emissions, are expected to switch out their bunker fuel for alternatives like green ammonia, methanol or biofuels. Meanwhile, many electric boat startups are vying to replace smaller fossil-fueled boats with what are essentially aquatic electric vehicles — powered by lithium-ion batteries and fueled up at charging stations.
But the idea of running boats on solar energy has gotten a lot less attention. In Borton’s view, that’s a mistake. He thinks solar is an underappreciated power source for boats — oe that can play a meaningful role in transitioning the entire maritime sector away from fossil fuels.
Making the Solaris
Borton has spent nearly two decades designing, building and captaining vessels that run on the power of the sun.
He built his first solar boat back in 2005 and has since built or designed nine more. In 2013, he retired from his decades-long career as a professor of solar engineering at the Rensselaer Polytechnic Institute to focus full-time on the endeavor. He founded his company, Solar Sal Boats, the following year.
After a few successful demonstrations of the technology, including a solar-powered cargo run up the Erie Canal, Borton realized that for his company to scale up, he’d have to get the blessing of an outside source.
“I really needed Solaris as a Coast Guard–inspected boat so that if anyone says, ‘Solar boats aren’t serious,’ I can say, well — ask the Coast Guard,” he said.
Not only does the approval lend Solaris some gravitas, but it also legally allws it to carry more than six paying passengers, Borton said, making the vessel a viable replacement for things like commercial tour boats.
But Borton is not a Coast Guard–recognized boat-builder, so he needed help to carry out his plan. That brought him to the Hudson River Maritime Museum, which has a wooden-boat-building program helmed by renowned local woodworker and boatwright Jim Kricker.
“David approached us, and he knew about Jim and…his incredible experience and expertise. And he said, “Would you like to bid on the building of my Solar Sal?” Lisa Cline, the museum’s executive director, told me. “And we said, ‘Of course we’d like to bid on it.’”
After several years of Kricker and team toiling away on the Solaris in a barn on the museum’s campus, the staff grew attached. In 2018, as the project wound down, Cline recalled asking the museum’s board of directors what felt like an increasingly obvious question: “Shouldn’t we keep this boat?”
An under-construction white boat ispartially enclosed inside a large gray barn. Workers stand nearby.
Solaris under construction in a barn on the museum’s campus (Hudson River Maritime Museum)
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