It began as a garage project two-and-a-half years ago by a group of engineers that call themselves “hobbyists.” But on Memorial Day, Damon McMillan and his Bay Area team are set to launch a homemade solar boat, named Seacharger, on what would be, if successful, the first voyage by an entirely solar-powered, pilotless craft across the ocean (or at least the greater part of it, as the destination is Hawaii). Previous unmanned solar craft used wave and/or wind power to augment the sun’s power, and a previous solar-only craft that made a voyage round the world had a human pilot onboard.
According to McMillan, who has an MS in aerospace dynamics and works in the unmanned vehicle industry, the Seacharger project started out as an attempt to create a robotic sailboat that would cross the ocean, something that had never been successfully done. Somewhere along the way, the sailboat idea got scrapped, and the boat became a solar-powered motorized vehicle.
The team began at the end of 2013 by gluing together two dozen foam pieces to plug a fiberglass hull mold. The vehicle measures 91 by 22 inches and is topped by two ultra-thin, Renogy 100-watt photovoltaic panels. The panels are attached to a lithium-iron-phosphate battery bank, suspended below the craft, which powers the brushless motor, similar to those seen in small hobby planes. The craft includes a watertight enclosure situated between the panels, containing an Arduino-based autopilot, GPS and satellite modem circuitry; this enables McMillan to navigate the boat from hundreds of miles away. Seacharger weighs 50 pounds and has a cruising speed of about three knots. McMillan estimates that in daylight it can go on indefinitely and, because of its battery storage, it can also travel for three nights before losing power.
Last month, McMillan tested the boat on Shoreline Lake near Mountain View, as recorded in his blog. The intended path of the boat was shaped like a rectangle, but its actual course more closely resembled a lasso. “Sure, it looked a bit like a drunken sailor,” McMillan wrote on the blog, “but it DID work. Just gotta tune some gains.”
The creation of Seacharger was, according to McMillan, a frustrating, trial-and-error process. “If I had started believing that I had to get to the end tomorrow,” he said, “I never would have continued. So it’s always just one step at a time.”
The team plans to launch the boat on Memorial Day from Avila Beach, a location about halfway between San Francisco and Los Angeles, where it will face possible high winds off the California coast.
“This is not a commercial project,” the team claims, “but simply a couple of hobbyists assembling a few pieces of ordinary technology to accomplish an extraordinary feat.”
You can track the boat’s progress online here.