Solar Sal Electric Boat Cruises All Day On Nothing But Sunshine

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The Solar Sal 24 electric boat can cruise all day on sunshine alone. Sure it has batteries onboard that can be used to power the boat after dark or when there is no sunshine, but by careful attention to the natural world, 10 people can enjoy a day on the water and never burn a drop of fuel or stop to recharge. It may be the perfect way to be out on the water and be part of nature rather than speeding through the natural world leaving a plume of pollutants in your wake.

Solar Sal is the brainchild of David Borton, a physicist and retired professor at Rensselaer Polytechnic Institute who has focused on solar power from its early beginnings. His Sustainable Energy Systems in upstate New York focuses on solar power and Borton has now made Solar Sal Boats a division of that business. For him, an important benefit of solar power is the chance to eliminate the use of fossil fuels that contribute to climate change.

He tells Arthur Paine of Maine Boats he has been involved in the development of several aspects of electric boating including direct current motors, batteries, battery charge controllers, displacement hull shaping, and solar panels. He says Solar Sal 24 and other electric boats like it will allow mariners to enjoy uncomplicated, quiet, reliable performance, while maintaining a clear conscience.

A key factor for Borton has been optimizing the overall efficiency of the power through direct current channels between the panels and the motor. Once he combined all that with a specially designed hull, he applied for and was awarded a patent.

Specifications & Specifics

The Solar Sal is 24′ long and 7′ 6″ wide with a draft of only 1′ 8″. Just as designers of electric automobiles concentrate on aerodynamic efficiency to improve range, designer Dave Gerr focused on creating a hull that would slip easily through the water. He actually went back to the design of naptha-powered launches from the 1800s whose needs for an efficient hull shape were similar.

The boat is powered by a 3 kW (4 hp) electric motor from Torqueedo, which also supplied 4 lithium-ion batteries with a total capacity of 14 kWh. The key to the electric boat is the canopy above that provides space for 4 solar panels with a maximum capacity 350 watts each for a total of 1,400 watts. That’s enough to cruise all day at around 5 knots without every tapping the energy stored in the batteries. List price for a Solar Sal is $124,500.

Why Would You Want One?

Borton is fully committed to solar power and a sustainable planet. He lives in a home powered by solar panels on the roof of his barn. “I didn’t just want to prove something,” he says. “I wanted people to have available a practical invention, one that is kind to the environment, and which could also be a commercial success.”

The first boats are being built at Belmont Boatworks near Belfast, Maine. Owner Dan Miller has already completed two more hulls that are waiting for customers. He says they will be ideal on lakes, especially ones with speed or horsepower restrictions. On many of those lakes, pontoon boats chug around all day long at around 5 knots but burning gasoline all the while. A Solar Sal 24 would fit right in, maintaining just the right pace to appreciate the scenery and while not scaring the wildlife.

If fishing floats your boat [pun intended], you can do it all day long at the ideal trolling speed of 4½ knots while consuming only photons, electrons, and bait. “The boat’s silence wouldn’t hurt your prospects or bother your neighbors,” Arthur Paine says. You also never have to worry about an explosion on board, something that is always a possibility with a gasoline powered boat.

Paine adds that while it is technically a powerboat, “It appeals to the sailor in me in that the boat is quiet, environmentally benign, and uniquely suited to a lifestyle remote from the concerns of the shoreside world because it doesn’t require a link to the electrical grid for recharging, and is therefore independent of fossil fuel. You could go exploring for weeks in the wilderness, without any concern about accessing the next gas pump or recharging station.”

Although the solar panels charge less vigorously on a cloudy day, according to builder Dan Miller from Belmont Boatworks the replenish rate is sufficient to go all day at five knots. “That’s familiar territory to a sailor.” Paine says. “Another similarity with sailboats is that most sailors I know are reputed to be parsimonious — a nice word for cheap. As fossil fuel becomes ever more expensive, Solar Sal’s owner gets to take a permanent pass.”

Paine thinks boats like this could be used as ferries in sun-washed places like the Bahamas. “There are many short ferry runs in the Bahamas where speed is unnecessary, and workers, townspeople, and tourists go back and forth all day long. Given the ample sunlight, a Solar Sal 24 could serve that route well. And you don’t even want to think about the price of gasoline [those places].” It is the first 100% solar powered boat to be approved by the US Coast Guard to carry passengers.

A Little History

Sustainable Energy Systems has previously built a handful of one-off wooden boats in different sizes. Solar Sal 24, a fiberglass production boat, is the next step. In addition to the prototype, two more hulls have been built and will be fitted out at Belmont Boatworks to the customer’s specifications. Borton is experimenting with a fifth model, a 16-footer that actually planes with a modest, 10 kW (13.5 hp) motor. His largest is a 44-footer that has been licensed by the Coast Guard to take paying passengers for rides on the Hudson River from its home port in Kingston, New York. Another of his boats, a 40-footer, made a cargo trip the length of the Erie Canal.

That is a key part of the story. A popular folks song back in the days when the Erie Canal was a thriving conduit for commerce featured these lyrics: “I’ve got a mule and her name is Sal. Fifteen miles on the Erie Canal. She’s a good old worker and a good old pal.”

The 40-foot-long Solar Sal Two actually carried cargo on a portion of the original canal, the first time a boat powered by the sun ever did the job that was originally assigned to mules. The name stuck. This video has some interesting historical photos to accompany the lyrics.

One of Borton’s concepts, a 27-footer built for Borton and his son, Alex, by Sam Devlin in Olympia, Washington, made the long passage through Alaska’s Inside Passage to Ketchikan and Glacier Bay. Even though bright sunlight is a rarity up there, Alex appreciated that as long as the sun rose, he did not need to worry about running out of gas.

People who own an electric car will relate to this next part. “It’s fun tracking the variables of an electric boat, basically a mix of watt-hours of stored potential in the batteries balanced with kilowatts of replenishment coming in from the roof. All electric boats have a “fuel gauge” in the form of a battery condition indicator. It’s up to the driver to select an appropriate combination of speed and range. A clever operator of a Solar Sal can trade speed for range. With enough patience, a solar-electric drive boat will always get home,” Borton says.

In Search Of A Sustainable World

Probably nothing illustrates the difference between a sustainable world and one that depletes natural resources faster than they can be replaced than a sailboat. When you are out on the water dependent entirely on the wind (or lack thereof), a bond develops between you and nature that simply cannot be replicated in any boat powered by an internal combustion engine. You will get there when you get there and no amount of oaths or carefully contrived invective will advance your progress one iota. A favorite expression among sailors is “We cannot control the wind. All we can do is adjust our sails.”

There is a benefit that comes from letting go of the constraints imposed on us by our fossil fuel powered environment and voluntarily submitting to the strictures of the natural world. It can provide us with a sense of tranquility and harmony and help us reconnect with nature in a way that is missing in much of our daily lives. Solar Sal 24 fits nicely with that vibe.

Hat Tip to Ken Anderson of Marblehead, Massachusetts, who first brought this story to my attention. Ken, Art Paine, and I grew up sailing on Narragansett Bay back when “I Like Ike” buttons were popular. It’s interesting how our early experiences intersect and loop back on each other over the passage of time.