Waterfront: Sun Powered, Coast Guard Approved

Former physics teacher David Borton has always taken an interest in two things: science and the water. Growing up, he spent a lot of his time on the lakes of New York’s Adirondacks and began earning his freshwater sea legs around the same time he learned to walk. As life moved forward, he became obsessed with his second love, fundamental science. So, when the oil crisis hit in 1974, Borton’s research-driven mind sought solutions. He set his eyes on alternative energy, namely the thermonuclear reactor 93 million miles away from Planet Earth we call the Sun.

Over time, the now 79-year old’s Troy, New York home became solar powered, and in 2005, he had a thought: The sun provides enough energy to sustain life on earth and power for his solar home, so it should also be enough to run a boat.

Borton wanted to see if he could propel himself across Adirondack Lake by strapping two small solar panels, a couple lead batteries and a DC trolling motor to a 20-foot Grumman aluminum canoe. The result? “It convinced me this was going to work, so I figured I’d build a bigger one,” Borton says. He retired from teaching in 2013 to start his solar boat-building company, Solar Sal, and set out to build a 25-foot solar-propelled boat using the design from a vintage wooden hull that dates back to 1906 when builders were still running naptha-fueled engines. She was equipped with SunPower glass panels, a Torqeedo Cruise 2.0 outboard and three 24V Torqeedo batteries. “We called it Sol: S-o-l for the sun and s-o-u-l because I spent nights and weekends putting my soul into building this boat,” he says.

In Borton’s words, it was the first practical solar electric boat, because the amount of power generated on its roof was matched by the amount of power needed to move it. “The way that works is by using efficient panels, efficient electronic controls, efficient batteries, efficient motors and an efficient hull,” he explains. “By putting all these together, you get a practical boat.”

Floating Sol on the Erie Canal one day, Borton overheard someone say “Oh, that’s a small boat, solar must only work in small boats.” At that moment a new challenge was accepted—go bigger. Borton ended up building a 40-foot solar boat. This one had 16 SunPower 360W panels, two battery banks (one for each motor), a cabin and was built to carry a few tons of cargo. Testing its grit, Borton took the model out of the Erie Canal all the way to the Niagara River where it was used to pick up four tons of cardboard, then brought back to the Hudson River to drop the load off at a paper mill for recycling. “That was fun, but people still thought these were toys,” Borton says, “I knew that if I got a Coast Guard inspected boat people couldn’t call them toys anymore.”

USCG approval means passing to two tests, Borton explains. One is a major stability test to check the design waterline by weighing the boat with concrete blocks, then moving the load to one side as if the cargo shifted, to see if the calculated response waterline is as stable as the side-loaded boat. The second is a major solar and performance test, involving running the boat for a calculated time under simulated emergency conditions such as nightfall, where there’s no solar input and only 1 battery bank. “Not quite as simple as seeing if your car can get home on a half tank of gasoline but roughly the electrical equivalent,” Borton says.

To develop a boat with Coast Guard approval, Borton, who at the time was not a Coast Guard-recognized builder, needed help. In 2017 he turned to marine naval architect and yacht designer David Gerr and a renowned woodworker named Jim Kricker who runs a wooden boatbuilding program at the Hudson River Maritime Museum. By the summer of 2018, they came up with a 44-foot displacement hull layered with 16 370W panels, providing over 5kW maximum power to a Torqeedo 12kW outboard. Able to carry up to 30 passengers commercially, the boat, named Solaris, has a top speed of 7.5 knots, an infinite range by day, according to Borton, and with 32 8D solar-charged lead acid batteries as backup (the Coast Guard didn’t approve lithium batteries at the time), enough electricity for 50 nautical miles of travel by night.

And while she may not be as fast as other boats, Borton says the added benefit of an electric engine is that you have full torque available at the lowest RPM’s, whereas on a petrol-powered boat, the slowest propeller speed is dictated by the engine’s idle speed. It’s also perfect for places like the Erie Canal, he notes, where the speed limit is 4.3 knots and sailboats are required to take down their masts.

Solaris is now owned by the Hudson River Maritime Museum, which uses the boat to ferry visitors along the local waters. Since then, the Solar Sal team has come out with a 27 and 24-foot cruiser and has created designs for a fiberglass version of the 44, which is currently available as made to order.

Borton believes it’s only a matter of time before solar-powered boats take over the market, as people begin to realize their potential. Thus, to expedite this realization, he’s put his boats to the test several times, including taking Solaris from the Erie Canal to New York City and back (over 500 nautical miles) and most recently, a trip aboard the 27 from Bellingham, Washington to Glacier Bay, Alaska, which Borton drove with his 55-year-old son Alex.

When asked if he plans to do anymore long-range tests to showcase his product, Borton laughs: “I’m the captain, but my wife is the admiral. If the admiral says no, you don’t do it. But that remains to be seen anyway.” As of late, Borton has been considering the idea of a 33-foot cruiser as well as additional deck configurations for the 24. He’s also sketching some initial designs for 100- and 600-ton solar electric boats. Why? As Borton simply puts it: “Because why not?”

This article originally appeared in the May 2024 issue of Power & Motoryacht magazine.

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Source: https://www.powerandmotoryacht.com/column/the-worlds-first-uscg-approved-solar-electric-boat