Arc of electricity leaves yacht dead in water

Apr 22, 2014 by Lucy Chabot Reed

To hear the captain tell it, his last trip up the New River in Ft. Lauderdale was interesting, puzzling, comical even. But he’s lucky to be alive.

We couldn’t describe the events any better than he does. He has asked that neither he nor the vessel be named as insurance claims continue to be sorted out, but he wanted to share his story to help other captains.

“It was early afternoon on a bright and sunny day in mid-January as I navigated a 70-plus-foot sailing yacht up the New River. I have been captain of this vessel for a while and she had me firmly in her grasp.

“Sailing vessels have that effect on mariners, as these boats that are our jobs get wedged between our calloused hands. I felt comfortable as we motored up this rather narrow, winding river in the heart of the city, passing through the many open bridges. I held the leathered wheel with a light touch.

Arc of electricity from power line that crosses the New River in Ft. Lauderdale leaves yacht dead in the water. PHOTO PROVIDED

Arc of electricity from power line that crosses the New River in Ft. Lauderdale leaves yacht dead in the water. PHOTO PROVIDED

“We were headed to a shipyard up river, 3.5 miles from the sea. My crew members were smiling and chatting as they set up dock lines and fenders. We had only two more bridges to go.

“As we passed through the railroad bridge in the heart of downtown, the mate had the binoculars in hand as he focused on marine traffic and the next bridge. The deckhand stood on lookout on the side deck.

“I was looking aloft at a set of overhead high power lines we were about to pass under. I knew we had plenty of clearance, as this vessel had been under these wires many times before, and yachts with even taller rigs navigate this river on a regular basis.

“Suddenly, a white fireball flashed around the upper two thirds of the mast followed by a massive explosion. It was so loud I thought there had been a bombing in the condos at the river’s edge and I instinctively spun around, bracing for impact.

“Instead of a building crashing down upon us, I observed a brilliant blue orb surrounding the boat, and then contacting and dissipating into the river astern of us.

“I now believe this blue orb was a plasma discharge released as the air molecules split apart, due to the electromagnetic arc that zapped us. This arc was so powerful and loud, that it pushed me down a little and stunned me for a moment. Or maybe I was just cringing from the blast.

“I took my hands off the wheel and looked at my crew. I know I said something before asking if they were OK, but events were happening very fast. The steering failed as hydraulic oil poured into the bilge from melted piping. A spatter of melted aluminum was visible part way up the mast.

“Then, somewhat apocalyptically, dozens of dead honey bees fell out of the blue sky onto the deck. My new deckhand promptly stepped on one, stinging her bare foot.

“The engine room fire alarm sounded, and black smoke immediately began to pour out of the exhaust blower vents. A loud hissing noise told us that the fire suppression system had released the 60 pounds of CO2. The interior of the yacht became engulfed in smoke.

“I mustered my crew in the cockpit to evaluate our options. We were now a smoldering dead ship, adrift in the river. Our tender was alongside and our anchors ready to go.

“But the boat still had headway, and with an ebb tide, we drifted close to the public docks at the Broward Center for the Performing Arts just ahead. In front of a sunny afternoon crowd of downtown tourists, stunned by what they had just witnessed and amazed that the three of us were still alive, we brought her alongside the dock with a spring line and a sheet winch.”

Starting the arc

The yacht was towed to the shipyard where’s she still sits, finishing repairs on all the damage. Ninety-five percent of the electronics onboard were destroyed, all but a few items protected by small fuses, such as a new Sony receiver, the KVH television satellite dome, and the Brookes and Gatehouse wind instrumentation.

Neither the captain nor any of the experts who have been onboard since can say with certainty what happened. Well, they know what happened — the electricity arced from the high-voltage transmission lines to the mast — but no one knows how or why.

The distance electricity will arc depends on three things: the voltage, the distance and the air resistance.

First, the voltage. Basically, the higher the voltage, the farther electricity can arc. Several phone calls to Florida Power & Light over the past month did not result in an answer as to just how much power is on those “high voltage transmission lines”. New poles were erected in the recent past and the lines were raised after several contact accidents in the 1980s and 1990s. The only thing a spokeswoman with FPL would say is that the minimum safe distance is 20 feet, which is difficult to apply if the height is unknown.

NOAA’s chart for that part of the river, on the western-most quadrant of chart No. 11470, doesn’t indicate the height of the lines or the poles, but states “OVHD PWR CAB AUTH CL 80 FT”, which means “overhead power cables, authorized clearance 80 feet”. Unlike notations for bridges, which give actual clearance, power lines give “authorized clearance”.

The captain whose sailboat was hit in January called that chart notation a “total absurdity, because the power company refuses to tell the public what the true height is.” His yacht has an air draft of 98 feet, including the lightning rod atop the mast, and he’s been up the river before. A yacht docked near him in the shipyard has 104 feet of air draft, he said, and makes the trip without incident.

It should be noted that the sailboat’s mast did not touch the power lines. The captain went up in the bosun’s chair and discovered a small area of melted aluminum where the stainless steel tang bolt must have contacted the aluminum mast about 50 feet from the waterline. None of the lights on the rig were damaged.

A tow boat captain who has run the river for 30 years said he doesn’t know how high the lines are either. He and a friend once shot it with one of those laser distance guns and figured out they were about 95 feet. But was that from where they were standing, on the deck of their boat, at arm’s length? He couldn’t say.

NOAA receives data for its charts from multiple sources, but considers the U.S. Army Corps of Engineers the “final authority for cable locations and specifications,” said Dawn Forsythe, a spokeswoman with the NOAA Office of Coast Survey. The Army Corps does issue authorization for aerial transmission lines and it’s possible a permit exists for that pole, but without a permit number, the details could not be easily researched before deadline.

The third condition that plays a part in an arcing incident is the air resistance, which is impacted by things such as humidity, dust and salt. Air is a natural insulator, which is why power lines are hung in the air. Humidity makes the air more conductive.

But that January day was dry and sunny at about 1:45 p.m. when the incident happened.

Overly hot days can make the wires stretch and sag, lessening the distance.

But that January day was cool, with a high of 74 and low humidity.

“We don’t really know [what happened],” the captain said.

“It’s certainly possible to have an arc that big,” said Steve Hebert, service manager at Ward’s Marine Electric in Ft. Lauderdale. “You don’t have to actually have made contact with the power line. Air, like any insulator, has resistance that can be calculated and overcome.

“You basically are bringing a giant lightning rod under those lines,” Hebert said, noting that the yacht was very well grounded. “This mast has low resistance to ground so the only resistance that has to be overcome is air resistance.”

“It’s like having those power lines 15 feet from the ground,” said James Cote, owner of Cote Marine in Coral Springs, a marine electrical consulting firm that does forensic investigations. “The boat is in the water, properly grounded with an aluminum mast. An arc can jump that far. Once an arc starts, it will continue. The hard part is getting it started.”

The missing ingredient?

When asked to try to explain the arcing incident, everyone’s first question is to wonder if the yacht was grounded properly. It was, by all accounts. A four-foot lightning rod is bolted through the aluminum mast and leads to bronze strips.

“Lightning protection is a little bit of a black art,” the captain said. “In the old days, we would dissipate a strike through a large surface like a copper plate on the hull. But when I redid it [a few years ago], the newest theory was that electricity best dissipates on a 90-degree angle, so we have 2-inch wide, 4-foot long, quarter-inch-thick bronze strips on both port and starboard, close to the surface of the water.”

Electricity experts agreed that was indeed a good system. Ironically, Hebert said a sailing yacht that is not well grounded probably has less of a chance of getting an arc started because there is a lot of resistance between the mast and ground.

So just how this arc started is unclear.

“Some people accuse the honey bees,” the captain said. “I wouldn’t have thought they could have created a frequency great enough.”

It might not be such a stretch.

“Bees are conductive,” Cote said. “They’re little flying bags of water. If they were between the mast and the lines, they could have contributed to it arcing over. I’ve heard of birds being on a line and spreading its wings and arcing between lines. Or the nest could have been hanging from the power lines.

“The bees are an interesting fact,” he said. “If they were stacked up over the mast to the power line, they definitely would arc through the bees to the mast.”

Not everyone is so sure.

“I think the bees were innocent bystanders,” Hebert said. “It’s a simple case of being close to the limit of tolerance.”

So was this a random, unfortunate accident?

“Pieces of the puzzle aren’t adding up,” Cote said. “It could just be a fluke situation with the bees.”

Several electricity experts interviewed pointed out that electricity doesn’t follow a pattern. It might arc on one side, not on another. In a crowded marina, lightning will hit one vessel, but not another, and not always the tallest one.

An electrical engineer who used to work at FPL offered this advice:

“Look at the length of the insulators on the towers,” he said. “If they are the really long ones, look out. You’re asking for trouble if the distance between your mast and the wire is less than the length of those insulators. Some of those wires can be up to 380,000 volts. I would not risk it if the two distances are anywhere near to being close. I would not bet on 8 feet of air gap being safe if the insulators appear to look 12 feet long.

“The problem is, I have no idea how you’re going to measure the length of those insulators or how to measure the wires’ exact height above the water,” he said.

So mariners are left to guess.

“There needs to be greater awareness about these lines,” said the captain who went through it. “This whole thing with overhead clearance is key, but they’re not willing to say what the distance is.”

This captain has worked on sailing vessels “my whole life”, joining the Merchant Marines when he was 16. He’s crossed oceans and traveled untold miles in his 40 years at sea. He respects the sea and cares for the vessels he runs.

“I’m an old salt, and I still love it,” he said. “I’m just glad my crew didn’t get killed that day on the river.”

Lucy Chabot Reed is editor of The Triton. Comments on this story are welcome at

Click to read related post, “New River power line crosses about 100 feet up“.

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About Lucy Chabot Reed

Lucy Chabot Reed is publisher and founding editor of The Triton.

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