Lightning????

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bartmac
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Lightning????

Post by bartmac » Mon Feb 27, 2012 10:56 pm

Having just spent 12days afloat on our Mac26X....and saw 2 very active storms c/w lightning......whats the go.....I'm I going to die if it strikes my mast

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Knot Tied Down
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Re: Lightning????

Post by Knot Tied Down » Tue Feb 28, 2012 1:57 am

I asked my sail maker about this and he said to attach a clip to something metal and have a wire run overboard. That should handle it? Thats all i can offer

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Wind Chime
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Re: Lightning????

Post by Wind Chime » Tue Feb 28, 2012 2:07 am

I have a set of jumper cables on board, and was told the best thing to do was to attach one end of the cables to the outside shroud and toss the other end overboard into the water.

If the mast is struck by lightning some of the current may be diverted into the water. And also to stay clear of the stainless steel compression post below as some current may arc from the mast step into the compression post.

Hope I never have to find out.

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Knot Tied Down
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Re: Lightning????

Post by Knot Tied Down » Tue Feb 28, 2012 2:17 am

Wind chime said what i meant, but in much better english! Thanks!

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mdeane
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Re: Lightning????

Post by mdeane » Tue Feb 28, 2012 8:48 am

Try parking among larger sailboats with taller masts, cheap insurance, I'm just sayin.

Marc 8)

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RussMT
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Re: Lightning????

Post by RussMT » Tue Feb 28, 2012 10:18 am

Wind Chime wrote:I have a set of jumper cables on board, and was told the best thing to do was to attach one end of the cables to the outside shroud and toss the other end overboard into the water.

If the mast is struck by lightning some of the current may be diverted into the water.
Lightning is a hot topic among boaters with metal poles above their boats, so this has been discussed quite a bit here.

Consensus seems to be that a jumper cable over the side would provide a pseudo electrical path to ground that would probably make the cable glow white hot and melt a hole through the side of your boat. Well, unless you could connect one end to a 3 square foot copper plate in the water. Water, even salt water, doesn't conduct electricity very well.

I've come to believe that if you can't ground your mast well, it's best to not try as that might make a worse situation. Yea, and I would not sit under the mast plate as lightning will likely try to find a path down there.

The good news is that surprisingly fewer sailboats are hit than you would expect. Those that are, generally don't blow apart and few fatal injuries occur. All electronics will likely be toast. Nevertheless, when you see lightning all around, it's hard to find comfort in statistics.

Like running away from a charging tiger, you don't have to be the fastest runner, just not the slowest. If you can get near someone with a very tall mast, it might increase your odds of not getting hit.

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Crikey
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Re: Lightning????

Post by Crikey » Tue Feb 28, 2012 10:27 am


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fouz
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Re: Lightning????

Post by fouz » Tue Feb 28, 2012 3:49 pm

On this subject.

The other day running down wires the PO ran in the boat I find a big battery wire going to the post at the centerboard. I thought he just ground it to the battery to stop corrosion or something. But its going to the port chain plate to the rigging. Neither are connected to the battery. just to each other.

Is this an attempt to stop corrosion or ground the rigging for a lighting strike.?

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Hamin' X
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Re: Lightning????

Post by Hamin' X » Tue Feb 28, 2012 9:27 pm

Food for thought: What is the most important thing that you need to attract lightning? A good ground.

What destroys most electronics during a lightning strike? Inadequate/unbalanced grounds.

Just sayin'...

~Rich

bartmac
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Re: Lightning????

Post by bartmac » Tue Feb 28, 2012 9:43 pm

OK so what can you do to forestall damage....my father says he used to use a piece of anchor chain around the mast and into the water....BUT I'm sure his mid 1900 mast was wood and not sure of the stays but maybe even rope... not sure the attaction for lighting but then in The Netherlands the tallest thing would probably be the mast of a boat...no hills

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Hamin' X
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Re: Lightning????

Post by Hamin' X » Tue Feb 28, 2012 11:14 pm

Russ had the best answer. If you are not willing to expend great sums of money for a complete grounding system, do nothing. Anything that you do on the cheap will just increase the likelyhood of your being struck and then you will find out that your makeshift ground will not carry the current of the strike. Trust me, the current will find a path to ground, just not via the path that you envision.

~Rich

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Ixneigh
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Re: Lightning????

Post by Ixneigh » Wed Feb 29, 2012 8:08 am

I've had a boat actually struck by lightning.

Boat: 22.2 Venture with free standing aluminum 18 foot mast
Location: few hundred feet from larger sailboats.
Damage: holes in hull, minor delamination in other fiberglass, shredded and burnt fiberglass and carbon fiber mast base wrapping, pinholes in centerboard trunk.
Ground method: none.

I was not aboard at the time, thankfully. I noticed the boat floating incorrectly and investigated.

Inspection revealed a foot of water in the boat. It appeared that the strike had traveled down the aluminum mast and into the yacht, arcing to the metal centerboard and exiting the hull near, but not directly beneath the mast step. Damage to the hull was limited to a palm sized area of pulverized fiberglass. Note that this was not a hole but rather a series of smaller perforations.
The glass sheathing of the centerboard was also slightly damaged.
No damage to pivot pin was evident. There was burnt carbon fiber that I had wrapped the lower part of the spar with all over the inside of the boat.
The wiring was ok. The radios at first seemed damaged but then recovered oddly.

Personal conclusions.

All my previous boats had stsinless whip antennas at the mast head. Even THIS BOAT before I refitted her as a Unicorn Lugger. None had ever been hit despite very close calls and not having wires in the water. I have always felt that the whip had something to do with it. A lIghtning rod of sorts to prevent charge build up.
You only need to be the 2nd most attractive thing out there.
All my other boats had deck stepped masts. Not sure of the differences.
I don't think this was a "hard" strike. I believe a hard strike could severely damage or destroy any boat.
I will however be putting a stainless whip on the new M before summer.
I file the end to a very sharp point.

Ixneigh

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Divecoz
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Re: Lightning????

Post by Divecoz » Wed Feb 29, 2012 8:48 am

I am with Hamin and Russ.. Best to do nothing... Just for fun / food for thought, if you were unaware.. The Fact Is.. The Higher The Voltage? The Less predictable its path...
I "might" speculate? a Center board in the water with a metal cable and all that in close proximity to a Metal Mast and a Compression post????? Hummmm
But then again.. Its TOTALLY Unpredictable..

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Catigale
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Re: Lightning????

Post by Catigale » Wed Feb 29, 2012 2:11 pm

Fouz.....it sounds like a crude attempt at strike prevention to me.

The compression post on an :macx: isn't even in contact with water, so the grounding wire isn't doing too much IMHO.

Even battery cable is small gauge wire compared to the current carried in a lightening (for Kevin :wink: ) strike.



...and incidentally, one of the posters above professionally grounded antennae for a living in past occupation.

Kittiwake
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Re: Lightning????

Post by Kittiwake » Wed Feb 29, 2012 4:46 pm

I gather one bottom line is the unpredictability of lightning and its effects, mentioned by Divecoz. I have chosen not to use any form of lightning protection other than to make myself the lowest point in my area when lightning is about. For me, as a shoreline-hugger by nature, this is usually easy on the BC coast. I am guessing though that, if I were to cross oceans, I might think seriously about a heavy (1" diameter) conductor from the mast, over the side of the boat to the water (but separated as much as possible from contact with the portion of the hull near-and-below the waterline).

The logic to my choice is as follows:
- the current & voltage in a lightning bolt are typically absolutely enormous
- any conductor carrying an ordinary strike (and the area which that conductor touches) gets heated to temperatures way beyond any of our personal experieces (with resultant explosive-shockwave consequences)
- lightning rods apparently act not by preventing a strike, but by offering a better path of conduction for the initial streamer charges than the nearby object you wish to protect ... so I figure I don't want anything attached to my boat to look better to the evolving lightning strike than say the nearby trees. ie. the strike is going to occur, with or without my presence in the area - I just want the preliminary streamers of electrons to find some pathway not attached to my boat. This is why I figure I might consider a lightning rod if I were in the middle of the ocean instead of near shore - my boat would then be the only game in town, so I might as well encourage the about-to-arrive discharge to take a path that wouldn't blast a hole below the water line.
Just my not-vastly-confident best guess and personal choice!
Kittiwake
ps. I gather it is now considered that sharpened lightning rods are less good than blunt ones (checked Wikipedia!)
Last edited by Kittiwake on Wed Feb 29, 2012 4:58 pm, edited 1 time in total.

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