As microprocessors find their way into a wide variety of marine equipment, just about every piece of gear on a voyaging boat works smarter and more efficiently. Unfortunately, however, this electronic proliferation has an Achilles heel: much marine technology has become vulnerable to lightning strikes.
Take two examples from this summer: A 40-foot sloop struck off Bermuda and a 140-foot schooner hit off Block Island. According to observers aboard each boat, neither vessel received a massive direct hit, instead receiving a lesser side flash or a pulse of elctromagnetic energy. Yet both boats experienced major gear failures. And while some of the damage occurred in electronic systems like chart plotters and radios that you might expect to be vulnerable, other malfunctions were more unusual: dead engines, balky bilge pumps, and unhappy refrigeration compressors.
Only a few years ago, a marine diesel would only malfunction from a lightning strike if the bolt blew a hole in the hull and sank the boat. Now, however, even as rugged a piece of gear as a diesel engine can be disabled by a lightning strike.
The reason for this new susceptability to lightning lies in the widespread use of microprocessors that can be knocked out of commission by stray currents. “Surprisingly, some of the things you don’t think of as electronic, actually are,” said Roger Hellyar-Brook, marine systems program manager at the Landing School in Kennebunk Maine. “Nowadays, there are so many electronics used (in marine equipment).”
Skater, the 40-foot Norseman 400 sloop hit off Bermuda, is owned by Cleave Horton, founder and owner of Sea Frost refrigeration. Horton and his wife, Darcy, were just off Kitchen Shoals when a bolt struck the top of Skater’s mast. As Skater did not have an air terminal (a marine lightning rod), the blast passed through the convenient VHF antenna at the masthead (vaporizing it in the process). The lightning current then flowed down the aluminum mast and exited to the sea without causing any damage to the hull. The equipment inside the hull was another story, however. “Everything electronic was zapped,” said Hellyar-Brook, who had flow to Bermuda to meet Horton and sail Skater back to the U.S.
“The SSB, the antenna tuner, radar, GPS, VHF, stereo and autopilot controller were all dead,” said Hellyar-Brook. But beyond that, other damaged or nonfunctional gear included bilge pumps and the pump used by the refrigeration system. These pumps had microprocessor controllers that fell victim to the electrical surge produced by the strike. One of the smallest victims of the bolt was the MP3 music player that Darcy Horton, who was at the wheel at the time of the blast, had in her pocket. When she looked at the MP3 player after the incident, it still worked, but a jagged line of burnt LCD lay across the screen.
Luckily for the Hortons, they had two full-fledged experts in Hellyar-Brook and a fellow Landing School instructor, Scott Lambert, meeting them in Bermuda to help sail the boat back to the U.S. When Skater arrived, Hellyar-Brook and Lambert went to work replacing gear and getting Skater’s equipment operational again. Still, the damage was widespread. “Anything with a transister or a diode was blown out,” Cleave Horton said. “Took me a month to get the boat back together. I didn’t realize what a mess it was.”
Another recent lightning strike involved the 140-foot wooden gaff-rigged schooner, Spirit of South Carolina, operated by the South Carolina Maritime Heritage Foundation. On July 27, Spirit of South Carolina was a few miles east of Block Island, R.I., headed for Newport, with a line of squalls approaching. Capt. Tony Arrow put the ship in heavy weather mode, sending the passengers below and battening down. As the squall line passed over, Arrow saw plenty of lightning. “We had lightning all around us and all of a sudden there was a big, bright blast,” he said. Although, true to the unpredictable nature of lightning, it wasn’t apparent how or where the bolt had struck Spirit. As South Carolina Maritime Heritage Foundation Executive Director Brad Van Liew, an experienced offshore racer and circumnavigator, noted, in the blinding instant of the strike, it’s not always apparent exactly what happened. “I have been struck close enough offshore and all you see is a superbright flash. It’s so disorienting you can’t tell the point of impact.” Immediately after the bolt, Arrow and crew checked the watertight integrity of the schooner and determined that there was no damage to the hull.
Like Horton’s Skater, the schooner’s navigation and communications electronics were fried. Spirit of South Carolina lost its hardwired VHF, SSB, computer and several chart plotter/GPS units. And like Skater, the schooner lost gear that many voygers might not expect were vulnerable. Since Spirit has Cummins Diesels as a corporate sponsor, the boat is equipped with twin Cummins QSB 5.9 common rail diesels. Both engines went off line when the bolt hit. Modern common rail diesel engines use microprocessors for engine control and for the engine sensors that provide operating data to the control modules. In the case of Spirit, these micoprocessors were damaged and the engines shut down. Arrow sailed Spirit to the mouth of Narragansett Bay where it met a commercial tow vessel and was towed to Newport Shipyard for repairs. After inspection by Arrow, U.S. Coast Guard personnel and a surveyor working for Spirit’s insurance company, the consensus was lightning never struck the boat. The damage to the vessel’s circuitry was apparently caused by the tremendous blast of energy, called electromagnetic pulse (EMP), produced by lightning bolts.
According to Hellyar-Brook, the issue of lightning damage to electronic circuits is a serious one for voyagers. “If you’re a passagemaker and you rely on this stuff, you need a plan,” said Hellyar-Brook. He advocates placing a boat’s electronics inside a metal box called a Faraday cage. The cage blocks the EMP that spreads outward from a lightning bolt. “Put all the electronics inside a Faraday cage,” Hellyar-Brook said. “And you could have a little locker for handhelds at the bottom.”
Of course, placing a boat’s navigation and communications electronics in a Faraday cage does not address the issue of the microprocessors on other gear scattered throughout the boat. Given the possibility of a lightning strike causing extensive damage, voyagers should be ready to run their boat the old-fashioned way. “It’s frustrating when everything is taken away from you,” Cleave Horton said. “But you have to be prepared to run the boat without the machinery and all your toys.”