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Old 19-07-2015, 16:44   #46
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Re: Offshore Sailing in Thunderstorm far from land

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Originally Posted by ozskipper View Post
Yep.. Guilty. Thats why I shared. Might prevent someone else doing the same thing.

She could sail the boat but not stop it. .
I had "assumed". That was the mistake. The assumption that another person had the skills required without first checking or testing them.
At least she figured it out eventually. Had a skipper once shout at us, "Stop the Boat!!!!!", and I sure as heck didn't know what to do, 2nd day in the ocean, maybe 6th time on a boat. Long time ago.

Now back to lightning and possibly virgins.

Ann
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Old 19-07-2015, 16:49   #47
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Re: Offshore Sailing in Thunderstorm far from land

Let me give you a bit of info on how a lightning rod protects a barn. First thing to understand is that the cable running to the ground rod could NEVER pass several hundred thousand volts at thousands of amps! But what it does do really well is emit electrons from the ground to neutralize passing rain clouds. So using that line of thinking, the electrons are going UP and therefore you should not climb up on the barn and put your hand betrween the rod and the sky, a burn is guaranteed. They are also pointed to allow better emmission efficiency.
I assume that your mast is akin to a lightning rod and that you are actually pasifying the clouds electron imbalance and therefore most sailboats left alone by the lightning.
Therefore, making your lightning rod (mast) a better emmitter of electrons would be most effective with a good ground connection to the water...... Your cone of protection looks a lot like your stays only inverted......
So, donate lots of electrons to the cloud and you should be ok.
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Old 19-07-2015, 16:53   #48
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Re: Offshore Sailing in Thunderstorm far from land

My boat was never grounded.
Never had a strike.
Guys with the bottle-washer up the mast got hit.
I turn every thing off when close to a storm, make it a dead boat.
Boats plugged in to shore power usually get hit with power surges. Been there, done that myself.
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Old 19-07-2015, 17:12   #49
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Re: Offshore Sailing in Thunderstorm far from land

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Lightning has been documented to strike 30 miles, laterally, from the storm clouds. So what the latest advisories are, is that if you can see it, or hear the thunder, get inside and protected as best you can, immediately. 30 miles is an extreme case, but that's how far it can reach out sideways.
Sideways, front wards and back wards.

A pregnant women was hit by lightning while tubing south of us yesterday. The group heard/saw the storm and got out of the river. After the storm had passed, they got back in the river and she got hit. She and the baby are fine.

I never thought of lightning hitting behind the storm though. I always hear and see the lightning as it heads to us and then away from us. If I am connected to work, I can tell when the storm is between me and the office because my connection to work will drop from lightning. I don't know if the dropped connection is from bolts hitting the ground and/or EMP but the connections will drop repeatedly during bad storms even thought the storm is miles from us.

Later,
Dan
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Old 19-07-2015, 18:43   #50
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Re: Offshore Sailing in Thunderstorm far from land

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Now back to lightning and possibly virgins.
Ann
OK, you have my undivided attention!
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Old 19-07-2015, 18:53   #51
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Re: Offshore Sailing in Thunderstorm far from land

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Crisis returned. My boat is berthed in LA right now, better chance of being hit by lightning than finding two virgins.

goat
Be verrry careful then. I hear there's been quite a bit of it in Southern CA as a result of TS Bertha.

On the boat today, we saw some lightning near San Francisco that seemed to be a cloud burst hovering over Daly City. My friend was asking what would we do if we went through it. I'm glad to see this post because it confirmed much of what (I thought) I already knew about being on the water in a thunder storm.
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Old 19-07-2015, 19:11   #52
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Re: Offshore Sailing in Thunderstorm far from land

Last week we had a powerful thunderstorm pass over, with some very close strikes. It prompted me to look up the subject of lightning. I highly recommend reading up on it. Even the wiki article is eye-opening. Those "bolts from the blue" are indeed the dangerous ones. A good thing I've set my heart on a steel boat...with steel masts. All I need now is some steel underpants (316 stainless, of course).
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Old 19-07-2015, 21:19   #53
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Re: Offshore Sailing in Thunderstorm far from land

I will go way out of my when dodging a storm. Got no real plan to avoid lightning. It moves a bit faster than most boats.


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Old 20-07-2015, 05:19   #54
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Re: Offshore Sailing in Thunderstorm far from land

I'm pretty sure we were hit by lightning at dock a few years ago. I wasn't on board, I was at work out driving a steel charter boat, but my then girlfriend now wife was on board.

It was an ugly storm, lightning everywhere, she was in the salon of my Grampian 30, very intentionally not touching anything metallic. She heard a big boom, the power tripped on the runway. I got home around midnight, she told me she was certain we were hit by lightning, I told her there were other boats around with taller masts around and it was probably just close.

I woke up the next morning to find little grey droplets of aluminum spattered about the deck. We didn't have any electronics on that boat, so I can't comment on how they were influenced.

In terms of tactics when lighting is around offshore, I don't think there is too much you can do if you've failed to avoid the storm. Any time I've been out on my sailboat with lightning around the only things I do is start the engine so auto can steer so I don't need to have my hands on the wheel. Stay low, and hope for the best.

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Old 20-07-2015, 06:07   #55
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Re: Offshore Sailing in Thunderstorm far from land

I've actually been racing a 33 foot sailboat in a squall w/a 35 a few yards off our stern which was hit by lightening. The strike hit the mast. The VHF antenna spun off like a baton, and the race continued. Back at the clubhouse, we had to inform the captain he'd been struck. He was totally unaware. A few days later he pulled the mast. The top was melted. New mast. Actually, even the hardware kept working, since he obviously had put the boat to bed before heading for the bar...
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Old 20-07-2015, 11:32   #56
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Re: Offshore Sailing in Thunderstorm far from land

I have been through several Thunder Storms and Squalls, I go below, say a prayer, and wait for it to blow over.
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Old 20-07-2015, 12:11   #57
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Re: Offshore Sailing in Thunderstorm far from land

Funny this should come up, I just got off of two weeks vacation sailing from Panama City FL to Key West and back up the coast, about 900 miles total.
Went through four thunderstorms, had my first and hopefully last knock down. Biggest learning experience for me was the Radar, at least the 4G B&G is excellent for spotting formed cells, all the way to it's 36 NM range limit, and you can often avoid the worst of the cells, or at least prepare.
I got knocked down about 100 NM North of Key West due to stupidity, had full sails up in a pitch black night, no moon, got hit with 50+ kt gusts that came out of nowhere. I know better than to carry that much sail at night, but we had been motoring for two straight days, and had just gotten sailing winds, so I got greedy.
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Old 26-07-2015, 09:20   #58
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Re: Offshore Sailing in Thunderstorm far from land

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Originally Posted by carlheintz View Post
At first sighting, you should attach your ground cable to the stern stay. The grounding cable is made up of half of a battery charging cable ( the big wire and clip) and the end is bolted onto a piece of 1" or larger copper pipe, about one or two feet long, that drags in the water from the stern. Sure, you have a ground on the boat, but have you ever seen pictures of what happens when 100,000 volts hits the mast or stays and tries to get to the water? It pulverizes the fiberglass around the chainplates. You either sink, catch on fire or have a boat with a zillion holes in it. Don't mess with electricity. Give it an easy way to get to the water.
Lightning happens so fast that the pulse mimics alternating current at about 200 kilohertz. What happens at these frequencies is the current is at the surface of the conductor. It's called surface effect. If you inspect a boat hit by lightning, those zillion holes are right at the water line since seawater is a good conductor at lightning voltages and surface effect takes place. Trailing a conductor off the back stay at the surface of the water puts your ground right where you need it, better than a ground through the fore stay into the chain locker into the fiberglass with super heated steam blowing things apart, or whatever uncontrolled path the lightning wants to take. If you trail grounds at the water surface from the side and back stays, the electromagnetic pulse created by the lightning going the various paths will tend to cancel out the voltages created in sensitive integrated circuits. All it takes is about 10 induced volts to take out modern electronics. The old tube radios and transmitters could deal with these voltages. I was once a member of a radio amateur club that had a radio shack at the top of a 10 story building that got hit all the time by lightning, but it was all vacuum tube so no problem. We were also careful to put antenna coax to ground whenever we left the shack.

The electronics are getting so compact that putting it in a microwave, or a cash box, can protect it. You need heavy steel because the Faraday cage cancels the "magnetic part" of the electromagnet pulse. There is also an alloy used in aviation electronics that will shield electronics, but I forget what it is called.
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Old 26-07-2015, 10:14   #59
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Re: Offshore Sailing in Thunderstorm far from land

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Originally Posted by CSY Man View Post
My boat was never grounded.
Never had a strike.
Guys with the bottle-washer up the mast got hit.
I turn every thing off when close to a storm, make it a dead boat.
Boats plugged in to shore power usually get hit with power surges. Been there, done that myself.
Yeah, I'm a firm believer that lightening is unpredictable. In theory electricity prefers the shortest path (not sure what that means for those of you thinking you should use the back stay with a ground to water vs a shorter side stay) But one only has to look at the horizontal bolts of lighting that often occur in a big storm to realize.. it don't follow rules! or if it does they are very complex.
I too have had a boat struck by lightning unknowingly. The windx and VHF antenna were melted and there were black deposits on the mast at both side stays. It obviously traveled down both side stays, no evidence on the back stay.
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Old 26-07-2015, 11:29   #60
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Re: Offshore Sailing in Thunderstorm far from land

The material Westwinds refers to is called "MuMetal" It's a soft sheet material that looks like aluminum but it's not.
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