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Be lightning alert

2016 April 1

Take steps to avoid lightning strikes, but be prepared if the odds are not in your favor

Gilles Martin-Raget photo


Recently I received a phone call from a sailboat in the middle of the Pacific Ocean, more than 1,000 miles from the nearest landfall. The boat had been struck by lightning and the autopilot, chartplotter and navigations instruments were all wiped out. Serendipitiously, the satellite phone remained unscathed. I was able to help the crew, made up of good sailors who were familiar with the boat, navigate by dead reckoning from my desk 3,000 miles away. It was an important lesson on lightning damage: You never know what or how much will be damaged in a lightning strike and in today’s digital age, there’s nothing more basic than a cell phone.

To truly understand lightning and make a strategy for safe sailing, the best place to start is the fine print in your insurance policy. If your deductible is double or more for lightning claims, it should tell you that lightning finds the most expensive stuff to demolish. If your policy completely rules out certain locations and times of year, the obvious conclusion is some places have a lot of lightning and you should stay out of a storm. 

If you keep reading the fine print, you will find thousands of pages of lightning science and reporting. Read enough of it and you will finally conclude that scientists still disagree about lightning, but insurance companies do not: Lightning is dangerous.

Prepare yourself and your boat for storm season by understanding your boat. Review and understand the basic language of boats and lighting: ground, earth, bonding system, D.C. negative, shore power ground, 4-gauge wire, 8-gauge wire, ground plate; these are often mixed in hazy confusion. If you follow the green ground wire around your boat, it will lead you to places and pieces you should know about. If you find a through-hull you forgot, the exercise has already paid off, so check it for leaks, loose or rusty clamps or a stuck handle. Take a picture, make notes and keep going. Keep a special file for pictures of pieces you don’t understand. If you find, for example, a through-hull that’s an odd mix of metal and plastic pieces, you are correct to not understand it. Lightning will heat the metal and melt the plastic. 

Protecting your boat

Since lightning protection for boats is an evolving science, it’s impossible for boatbuilders to be current. Many of the latest hardware solutions are not applicable for reasons of cost, weight or corrosion considerations. No one would put 50 feet of 4-gauge copper wire on a race boat and expect to sign up competitive crew. But understanding why all major metal pieces of the boat are bonded together, and locating them in your boat, is good for your general understanding of your boat, its systems and what problems can come up. 

There are products on the market specifically geared to helping prevent lightning strikes, but none claim to be 100% effective, which is no surprise given the unpredictable nature of lightning. Forespar’s Lighting Master Static Dissipater uses the same technology that is used to protect television towers from direct lightning strikes and mounts to the masthead.  

The science and technology of lightning protection keeps moving without gathering clear consensus. You can outfit your boat to a recent standard but you have no control over all your neighbors, whose boats have an effect on your own. If you move to an isolated spot, you may join a group more statistically likely to be hit: loners. But many of the commonly recommended measures for lightning protection also come up universally in good electrical practice. Consult a good electrician and bring your boat up to sound electrical safety standards and you might avert a lightning strike, but you will definitely protect yourself, your neighbors and your boat against many more common dangers. 

What will do you if you’re hit?

If you have inspected your boat, and you now comply with the latest in lightning protection theory, don’t stop. Think your way through the worst case. What if you are out in a storm (don’t go!) and you are hit (low odds, bad luck)? 

Start with the first aid kit. Pay special attention to burn and cardiac treatment as well as shock (not the electric kind). Review with your crew and understand special needs. Does anyone have cardiac trouble? Implants, pacemakers? If your last CPR course was high school summer camp, it’s time to refresh. CPR canon seems to evolve as fast as lightning. 

Back to the through hulls. Find your collection of tapered plugs and any other material for blocking new holes in the hull. Review with crew all your pictures and diagrams of locations and strategies. Let each one tinker with bilge pumps till they know how they work. 

We are all GPS button pushers now, but lightning can defeat the most professionally installed, reliable and redundant system. Think about how will you get home, or even around the rocky point in the dark, in rough weather when all the lights are out, the autopilot quit, your navigator is seasick and you don’t feel too great yourself.

It’s hard to read paper charts in a moving cabin when the lights are out and you’re seasick. Flashlights with good batteries are a requirement.

Small, battery-powered GPS receivers are so inexpensive and reliable it’s hard to justify not having two or three spares stashed around the boat. Keep one in a dry place far from any metal, if you want to give it a chance to survive lightning. But a small GPS that reads latitude and longitude is little help without a paper chart to show where you are and where you want to go. 

Most of these little units can store waypoints and routes. Even if you lost the chart, or can’t read it, you can still get around if you pre-program the receiver with all the most useful positions: harbor entrances, dangerous rocks and shoals, channel markers. 

If lightning has reduced your options to the most basic, remember that dead reckoning, carefully done, is remarkably accurate. Keep a good log, a strict record of course, speed and time, and you will have a solid foundation to fix your place on the map with nothing but a pencil and a straight edge. 

Course, speed and time are all well provided by that little GPS and the sensible backup is another little GPS unit, of course. Backing those up is a reliable, accurate analog clock and a well-honed sense of approximate speed, measured by your own eyes and brain. And that card compass that gets so little attention these days should be checked for good fluid, clear glass and accurate adjustment. 

Believe it or not, the news can get worse. Lightning has a wildly strong field effect that has turned a card compass 90 degrees or more off kilter. If you’ve been struck, you can’t even assume your compass is right.  What will you do with no sense of direction? As long as the sun still comes up in the east, you have something to at least suggest it’s California ahead, not Japan. And there are ways to use an analog watch for a crude compass. 

When in doubt, just stop

If you know the reef is somewhere out there but you don’t know where or how far, it’s pointless to guess. You have a better option: stop. If you can safely get an anchor down, great, but in deep water you should know how to heave-to and how your boat will balance under all wind and wave conditions, with the right amount of jib backwinded and mainsheet off or trimmed loose. 

Lightning is a fickle foe. No one knows where it will strike or when. And if it does, it can destroy a boat or leave it as quickly as it came without so much as a blown fuse. Know your boat and know what to do if the worst happens and you’ll be ahead of the game.