Chapter 88: The One With the Lightning Rod

When our son was little, he love a show called “Rescue Heroes”. He watched all the videos over and over and had all the toys and gear. We spend endless hours playing Rescue Heroes. His favorite episode was called “Electrical Storm”. It was a nail-biter. Billy Blazes, Wendy Waters, Jake Justice. Quite a crew. Frankly, we could have used the crew last night. We’ve been in George Town, The Bahamas for the last few days to ride out a storm system passing through. Friday night was really windy (up to 25 knots) with a lot of chop in the mooring field. Last night, though not as windy, was more nerve-wracking. As the front passed through we had a lot of lightning.

Electrical storms are scary enough on land, thank you very much. But on a boat, it’s a whole other level. First of all, one is sitting in, essentially, a big puddle-the water-which is a great conductor. Second, a sailboat has a big metal pole sticking up in the air. When there is a thunderstorm, does it occur to you to go hug a flag pole? I thought not. This does not seem like a great situation. And, in fact, it’s not. Lightning can affect boats in two ways. First, there is the direct strike, in which lightning actually hits the boat. This is actually the less common scenario, although it can be more catastrophic. The electricity travels down the mast and through all the metal on the boat. Unfortunately, this can include the through-hull fittings, which can be blown out and then the boat can sink rapidly. The second, more common scenario is to be affected by the EMP-the electromagnetic pulse. This can be sneaky because not only does the boat not have to actually be directly struck, but the damage may not manifest for days, weeks, or months. EMP damage can happen even if a boat hundreds of feet away is struck. An EMP damages electronics, of which there are a surprising number on most boats: refrigerator/freezers, water makers, chart plotters, VHF radios, autopilots, instrumentation, battery management systems, inverter/chargers, and of course, phones, computers, and tablets. It doesn’t matter whether they are off or on. They can be damaged just the same.

What can we do? Not much actually. For direct strikes, the boat is grounded, with grounding wires running from the mast and other metal parts to the hull, but these are more wishful thinking than practical-they have never been shown to be effective and the current with a direct strike is so huge that the grounding wires couldn’t handle it all anyway. To protect against EMP damage, people will put portable electronics inside the oven to act as a sort of Faraday Cage, but this too is of questionable benefit. At the end of the day, one can really just hold on and pray. In our case, fortunately, that strategy was effective. We appear to be unscathed. The same, unfortunately, cannot be said for others in our anchorage. Six boats were struck here last night and are dealing with the consequences. Fortunately, the damage seems limited to electronics and no one was injured. So we will be thankful this Palm Sunday and look forward to celebrating Holy Week!