Struck by Lightening

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Brad Cavedo

Our H P42 was stuck by lightening at about 5:15 Saturday morning. We were awake at the time in the aft cabin. We were about 1 hour into a storm that flashed lightening about every 2 or 3 seconds. In 20 years of sailing on the Chesapeake Bay [in a H36c prior to the 1997 P42] we have never been struck to our knowledge. In April of this year we had an ion dissipater installed on top of the mast. Did it work or did it attract the strike??? Who knows. We had virtually no damage. The autohelm ST7000 pilot does not engage and does not receive data from the GPS, but the other Sea Talk functions still work. The anchor light works, but a cabin light that used a dimmer blew out the dimmer. The TV antenea works fine as does the wind indicator and the VHF. But when we were hit, sparks rained down on both sides of the boat. So what was that? The inverter/charger, which was on at the time, seems to work fine as does the TV and microwave and airconditioning. So one light and a blown something on the auto pilot seems to be it. Maybe the sparks were the ions dissipating just as the bolt approached?? Who knows. If we had come down on saturday morning instead of friday night, we would just think the aupo pilot broke and would never have known about the lightening strike, because it left no trace.
 
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Mark Johnson

Glad you are OK..

Brad: Lightning is a scary thing. None of my boats have ever been struck, but have been in some very scary situations with lightning. Glad there was only minimal damage. Maybe Hunters grounding system really does work?? MPJ
 
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bill walton

also glad

Also glad to hear you and your boat are okay. I've seen lightning coming down the harbor at my P42 and wondered what would happen if we were hit. I always try to be around other masts when the lightning is heavy. There's something reassuring about the odds in a crowd :) Best Wishes, bw
 
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Wayne Estabrooks

Lightning Dissapator

I read with interest your report of your lightning strike. I work with tall television broadcast towers up to 2000 ft. and we use similar lightning dissapators on our towers. Most that I have seen after they had been up for a season, had many of the pointed needles melted or burned off. I suspect the sparks were from the needles in your dissapator getting melted / vaporized by the lightning. If you get hoisted up the mast and inspect the dissapator I'm sure you will see the damage there. I hope your insurance company pays to fix your autopilot.
 
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Matias II Santiago

Been there...

Just after our boat was commisioned we got hit by lightning at the marina, It damaged all the instruments, the battery charger, the engine alarm, the CD player and a few light bulbs. When I called Boat US, they recommended that I haul the boat and check the thru-hulls, they sent surveyor the next day to inspect the damage. We were inside the boat but did not heard any sounds or saw lights. It blew up the VHF antenna like a fire cracker with the burned epxy scatter all over the deck. BoatUS Was very quick in paying the claim.
 
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Brad Cavedo

Hit was a deflection, it turns out

Well, it turns out that a Sabre 40 four slips beside ours took the direct hit. We got only a deflection or some other sort of charge. The sparks we all saw raining down was everything on top of the Sabre mast. VHF, TV antenna, wind direction, Windex, anchor light. They left many burns in its deck gelcoat, even though it was pouring rain at the time. This explains why our mast top was unscathed and why out damage was so minimal. Makes me feel a lot better about our ion dissipator.
 
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Mark Kissel

Whew! Close call.

Brad, It is likely that your damage was produced by inductive coupling. Curious, were you plugged into shore power at the time? Do any of your slipmates have damage? Mark Kissel s/v Kittiwake H240
 
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Brad Cavedo

Plugged in

We were plugged in on one 30 amp cable at the time. Fore and aft air conditioning, freezer, refrig, courtesy lights, Heart inverter/charger were on. Instruments, autopilot, fans TV antenna were off, but microwave and TV were "on" at the panel but off at the unit. A boat between us and the Sabre that took the direct hit reports that his instruments are all screwed up. The Sabre is a mess and will need considerable work.
 
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Rich McCue

we got hit too.

We took a hit on 8/15/99 .I lost all electronics,inc,fuel gauge? I'm going to have boat pulled next week.
 
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Mark Kissel

A few facts...

Swapping captain's hat for work hat... First, Brad is concerned about electricity from the sky (lightning), not the sudden desire to throw things overboard (lightening, except maybe on race day). Since there's so much misinformation, maybe this will help. A typical lightning strike produces 10-20 million volts, 30,000 amperes of current, and leader channel temperatures of 50,000 F (about five times hotter than the surface of the sun). If you are hit directly, you WILL incur significant damage regardless of your grounding system, surge arresters, or static dissipator. Fortunately, direct conduction events are not that common (I'll probably get a zillion "Mine was hit" emails). Nonetheless, the greatest damage is produced by the magnetic field generated by the current flow in a strike. Whenever current flows, magnetic fields are generated. As the field radiates away from the strike and crosses long, thin conductors, such as telephone lines, TV cables, or other similar wires, it creates or "induces" a current. We call this process "inductive coupling". It's not magic or mystery, your local power company uses this principle of physics to generate electricity. Unfortunately, inductively coupled currents can be quite high near the strike point. Long conductors pointed directly at the strike will receive a maximum of induced current while those perpendicular to the strike get a minimum. Most people assume that lightning enters their homes (boats) through the power system. While this does occur, it is more common that damage is generated by inductive coupling. For example, computers with modems are quite often damaged while those without are not even though both are plugged into the same outlet. In this case, the telephone lines provide the path for inductively coupled currents. Your dimmer and Autohelm were likely damaged by induced currents on your boat wiring or signal line wiring. Make sure you excercise all of your electrical systems for at least 48 hours. Latent damage from lightning strikes is mostly myth and hysteria. If you took a hit or a near-hit, affected items will typically fail within the first 24 hours after power is applied (not six months after the fact). After 48 hours, the odds are nearly 100 percent that the electronics will last their intended life span. I'm glad your were only "grazed" by the magnetic field. My condolences to the owner of the Sabre. Mark Kissel Regional Manager/Sr. Technical Consultant LWG, Inc. (sometimes called "the lightning people") s/v Kittiwake H240
 
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Brad Cavedo

Thanks for your comments

Thanks for your comments Mark. This is very useful information about lightning [which I misspelled throughout my first post, but got right in my second.] I think you have described well what actually happened to us and what we can expect in the future from our electronics. We used everything all day saturday and sunday without additional failures, so I think we might be OK.. We did not use the generator yet. We will see if that works this weekend.
 
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