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Old 06-02-2007, 08:48 AM   #1
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I have been thinking about and studying the topic. Here it has not been discussed recently.

Some sources say, "Lightning strikes somewhere on the surface of the earth about 100 times every second." ...OK boat in conductive salt water, linked to ground, stick in the air, stick in the air is likely metallic, stick in the air is the highest point in 12.5 NM in any visible direction, saying: "Pick me, Pick me" ......just asking for it.

Other Sources state that a typical cruiser has a fair to high probability of being struck at least once.

Surveyors often are called upon to inspect vessels damaged by it.

Some statistics say about half of the boats take some form of defensive measures.

What do you think, and do as a precaution?

For life, electronics, and vessel?
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Old 06-02-2007, 12:08 PM   #2
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Good luck - Here is study done in Fl several years ago. Nicely done by a Professor and he got paid for it.

http://www.thomson.ece.ufl.edu/lightning/

Still way to much hype for me to fully grasp it for a small boat. About the only sure thing that you can do is wrap all spairs in foil and when something goes you will have a spair.

I hope that you find something new.
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Old 06-02-2007, 12:28 PM   #3
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I have never been struck by lightning in a yacht ...... and I don't want to be. On the other hand, when I was third oficer on an 80,000 ton bulk carrier we were struck by lightning off the coast of Liberia.

There was an almighty bang, as if an explosion had taken place, and then nothing. That was it. Of course, the steel hull conducted the charge directly to earth/ground but we suffered no damage whatsoever except for both magnetic compasses. Prior to the strike their error had been maximum 5 degrees (after compensating for variation). After the strike they could be anything up to 180 degrees out. Of course the error was not constant either so they were totally unusable. We were on our way to Baltimore where we shipped new compasses on arrival. Thank God the gyros didn't go south on us too.

Makes you think though! What would you do. You are well out at sea. The compasses stop working for one reason or another and your GPS goes south. Nothing to indicate the course being steered. What would you do? Now I am digressing from the topic but it is worth considering.

As for me, I have a portable VHF, GPS and a compass which I keep in a metal box (Farraday's cage) and hope they will not become damaged. I have never used them yet but I also keep haevy cables which I clamp to the shrouds and keep the other end in the sea in the ope that any charge will dissipate that way.

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Old 06-02-2007, 02:10 PM   #4
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When we were in Singapore on Exit Only, our Privilege 39 Catamaran, there were five yachts struck by lightning in a single week in the Singapore Straits. Most of them lost all their electronics with the strikes.

It was a scary place to sail, and we were plagued by frequent thunderstorms until we arrived in Northern Malayasia - Langkawi. Although we have never been struck by lightning, we do carry two static electricity point discharge devices on the top of our mast. I don't know if they really work, but they make me feel better being up there.

I read in a cruising guide that each year, one out of a thousand boats get struck by lightning in the Bahamas. I can believe it, because there are afternoon thunderstorms nearly every day when I have cruised over there.

We always avoided lightning by changing our course when we were near a giant cumulonimbus cloud that was sending fingers of lighting down to the water. We found that by keeping a good watch, most of the time we could keep our distance from those monster thunderstorms. We made it more than 33,000 miles around the world without getting struck. I hope our good fortune continues.

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Old 06-02-2007, 03:18 PM   #5
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A friend of mine in Florida is a marine surveyor for insurance companies. He runs into this often especially with small non metal boats. The general rule is if there is a threat of a thunder storm don't go out or as soon as you hear the warning head to shore. Yes if your the tallest object around you take the chance of getting struck. The best thing to do is to make sure everything electrical is grounded properly into your boats protection system. If caught at sea the general rules apply. I am sure most of you file a float plan before departing on long trips just in case.
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Old 06-02-2007, 03:47 PM   #6
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Rather than reproduce it here, this is a link to our lightning strike: http://www.cruiser.co.za/hostmelon29.asp

sv Watermelon had a good bonding system, and was grounded.

We were on the Gulf of Thailand side of peninsular Malaysia, an area that we later learned is one of the worst places for electrical storms.

As I say in my log, I figured we were due to be hit. When we were sailing up the Pacific coast of Costa Rica, another place known for its hurricane season rain and lightning, we were in some horrendous electrical storms. Peter, with a more sanguine personality than mine, would say, "there's nothing we can do but ride it out. We'll see what happens." Although several times in our trip up and back down again we were in violent electrical storms with lightning crashing all around us, the lone sailboat in the area, we were not hit by lightning.

We met many boats that season that had been hit by lightning, the worst a trimaran anchored near Punta Arenas. Their mast was apparently not grounded, and so the lightning traveled down the shrouds to exit from the chain plates to the water, blowing holes in both amas on its way out, nearly sinking the boat. Everything electronic on their boat was destroyed by the lightning.

We saw a neighboring boat in a Malaysian marina get hit by lightning - the owners had left the boat and did not return in the time were were there, so I don't know what, if any, damage occurred on the boat.

Considering that in all the years we've been on the water in our boat, one lightning strike in all that time indicates that it is less likely than people fear. It makes me a bit sceptical of advertisements for lightning prevention gear for sailboats. I followed Lynx's link and it seems to confirm my own thoughts. To quote:

"Even if a device were effective in diverting the attachment spark, it would not be a good idea to mount it on the masthead as the attachment spark may start elsewhere on the boat or crew. The likelihood of lightning attaching to the masthead is a safety feature as far as the crew is concerned."

We've heard of boats who lost all their electronics even though they did not sustain a direct hit. Again, that doesn't surprise me that much. Peter figures that the electrical current in the water traveled to our SSB radio through the ground, for example. And the Man Overboard light, which was connected to nothing and was just hanging in our lazarette by a nylon line, was evidently damaged by the electical field. I still regret Peter's decision to replace our SEA ssb radio with an ICOM. I still believe that the SEA radio was better.

I've read of a boat that was sailing when it was hit by lightning (well, I think that was when they were hit), but every boat we've met that was hit by lightning was anchored or in a marina at the time of the incident. I wonder what that tells us?

I found the linked article to be very informative. Got any more, Lynx?
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Old 06-02-2007, 07:12 PM   #7
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I have been told that the best (and only) defense against lightning strikes is a:

GOOD INSURANCE POLICY!

Also, I hear that carbon fiber masts are particularly attractive lightning rods these days.
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Old 06-02-2007, 09:10 PM   #8
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Now I am totally confused. The grounding system in my boat was fully bonded by the original owner. There is nothing 'lightning specific' aloft but in the marina there is a connection from the bonding, directly to the seawater. I have never totally understood the physics behind lightning protection mainly because I have not really bothered to research it as well as I could have.

Darwin is Australia's, and one of the world's lightning hotspots with over 3000 hits at the Darwin Airport in one day last wet season. Yet, there has not been a case of a pleasure yacht taking a strike within Darwin harbour for just over 18 years.

A friend on a 32' catamaran copped a bolt off Mooloolaba about six years ago and lost most of his electronics. My attitude therefore is that lightning strikes are extremely rare and the microwave oven makes a good faraday cage (I think).

So I will sail on in blissful ignorance but will continue to toast both Neptune and Thor in the hope they will jointly recognise that I am a decent bloke, and worth protecting.

Salut Neptune (for the water)

Chin chin Thor (for the air) and, because he was so thoroughly grounded,

Campai Buddha.

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Old 06-02-2007, 11:26 PM   #9
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Greetings,

Every year I lose radio contact with some Mobile Maritimes as a result of Proximity Strikes - at least 20 - majority occurring in Lightening Alley - The Southern Malacca Straits into The Singapore Straights.

Besides losing the HF Radio - the VHF and most Electronics are damaged - Read :-

http://www.thomson.ece.ufl.edu/lightning/S...tion%20with%20a

This study , although done in Florida concludes that it is the electronics on board that are at the greatest risk from Proximity Strikes.

No deaths or injuries to crew as a result of lightning reported from cruising yachts to my knowledge in the last ten years. We have as many as a thousand cruising yachts in the waters of Malaysia - Singapore - Thailand alone, Thousands more in Northern Australia - Indonesia - Philippines.

Richard
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Old 06-03-2007, 12:55 AM   #10
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Here's my thinking with respect to lightning strikes and sailboats...now that I've been thinking about it.

Electrical Conductivity (S•m-1)

Silver 63.01 × 10^6 Highest electrical conductivity of any metal

Copper 59.6 × 10^6

Aluminium 37.8 × 10^6

Seawater 5

Drinking water 0.0005 to 0.05

Deionized water 5.5 × 10-6

So, Seawater is approximately 7 orders of magnitude less conductive than your typical mast and as such it provides excellent insulation. The surrounding air can achieve a high level of electrical conductivity through ionization to form a plasma when in the presence of a strong enough electric field. Therefore, it would seem that the only reason lightning would strike a boat would be that it has provided a less resistive path to ground than the surrounding water. Such a case would be in shallow water, at anchor or operating RF equipment (or all the above).

My understanding is that boats in a marina typically have a much lower likelihood of being struck by lightning because there are a large number of sailboat masts, electrically grounded by shorepower, all acting like lightning rods. The large number of lightning rods in a given area reduce the local electrical potential by slowly drawing current from the atmosphere and preventing the sudden discharge of electricity through a single ground source and lightning strike.

Therefore, I would theorize, that being at anchor in shallow water without neighboring anchored sailboats would greatly increase the probability of being struck. So, if you find yourself in a strong electrical storm, either find your way to a marina, or sail out to deep water and turn-off all of your RF equipment…don’t drop anchor.

Of course, I could very well be completely wrong
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Old 06-03-2007, 01:13 AM   #11
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Quote:
Originally Posted by Trim50 View Post
Therefore, I would theorize, that being at anchor in shallow water without neighboring anchored sailboats would greatly increase the probability of being struck. So, if you find yourself in a strong electrical storm, either find your way to a marina, or sail out to deep water and turn-off all of your RF equipment…don't drop anchor.
Now, that fits in with those circumstances we've experienced. Where we were hit by lightning, we were the only boat at anchor in the bay.

Those many times we were sailing through HORRENDOUS electrical activity all around us, we weren't hit.

One of the boats that got hit by lightning in Costa Rica was just a tad bit anti-social and had moved far from the group of anchored boats to be "alone". Oops!

So the answers, I guess are: keep sailing, and don't stop until you can find a lot of boats to mingle with.
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Old 06-04-2007, 08:07 AM   #12
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Some more info:

Lightening protection for sailing boats.
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Old 06-04-2007, 09:56 AM   #13
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JeanneP - Sorry, no more like that one on Lightening. As I recall, the author said that you could email him. That might get you something.

When I was in Bimini Bahamas last May a boat had the VHF fried during a storm. No other boats there mentioned anything. The said that a blue glow was on the mast head.

I have seen the lightening protection wiring on buildings melted before. It would seam that a little protection is of some help but I do not think that we could put something big enough to handle a major storm. Really a bit confusing.

Yes, the Mircorwave would be a good place to put something to protect it from lightening if it is unpluged. A metal box is also a good place or wraping it in aluminum foil.
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Old 08-01-2009, 05:43 PM   #14
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Anyone have recent findings/information on this topic?
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