Lightning Protection

[Stede]

Last Spring,I was caught out in a severe storm close to the Marquesas Islands, about ~20NM from Key West. There was a lot of lightning and it made me start thinking about how well my boat is prepared for such conditions. I have a book called "Offshore Sailing" by Jim Howard. In it, he has some good information on how to protect your boat from a strike.

"The most reliable system is to have a lightning rod installed at the masthead,extending higher than any antennas or instruments.It should be connected to the keel (via a keelbolt, for example) by # 8 AWG wire. Otherwise, the wire from the masthead should be connected to a through-bolted ground plate on the outside of the hull below the waterline. The ground plate should be as close to the base of the mast as possible. A lightning protection system applies equally to boats with wood,metal, or any other type of mast,although for non-metallic masts it is especially important."

"Another suggestion for grounding, occasionally espoused, is to link the mast and rigging with heavy electrical cable, such as welding, and attach it to a length of chain, which can be trailed in the water during an electrical storm. Some sailors rely on this as their only lightning protection. Although this may seem like an easy "quick fix" solution to the problem, it has its drawbacks. This is just some more gear to keep track of, and in a sudden, unexpected storm you may have many other tasks that will prevent you from rigging a tempoary grounding device."

The book has a lot of other good information around this topic, and associated bonding of the boats equipment. How about you? Do you ground and bond your boat?

[delmarrey]

This is the only time I believe in pure luck!
From what I've read the only thing lighting protection might save is your mast, If your lucky!
It's kind of like insurance. It gives you that sence of security until you get killed.
From the stories I read, it'll still take out your electronics and maybe even burn a hole in the boat even with the LP. But I guess some it better then none.
There is an artical on sailnet that gives the spec's for a LP system.

[Troubledour]

This is something that I've wondered about & haven't yet studied to any degree. Seems that 60 or 70 feet of mast would be a very attractive target in a storm.

My house was struck about a yr & a half ago ... it stuck the chimney & sounded like a bomb with similar results. No injuries, we were all downstairs at the time & two neighborly fire fighters helped to get the fire put out before the dept even arrived (so, no serious water damage).

I'm hoping that such an event is a once in a lifetime thing but will watch this thread with interest &, of course, do further reading. Good post Stede, thanks.

Troubledour

[Stede]

Wow! Troubledour, I can imagine what it must of sounded like when lightning hit your house chimney! Man, that's scary stuff!!

Del,

Skeptical are you? Well, I know what you mean. I have an electrical background,and I've seen some strange stuff happen with electricity.Where I work we have what we call a "wire" on a webformer. Basically it's a big continuous mat of nylon material that travels over some rollers,as it carries fibers through a process.The "wire" generates a lot of static electricity. In an effort to eliminate it, the vendor of the " wire" wove some copper strands into it, figuring that the static would be carried through it, to the metal rollers of the machine where it would eventually dissipate to ground. It didn't work. The damn thing actually generated more static, and gave one of the operators one hell of a static shock when they went to remove a wad of fibers off of the "wire". ha!ha!

I don't know how effective these systems would be either. In a house wiring system, grounding is what inspectors scrutinize the most. Of course a boat is a totally different animal, or should I say mammal?, than a house. It seems to me that providing a direct current path from the mast to the keel would offer some protection. Granted,I've also read stories where boats that had LP systems still lost their electronics,etc, but to me, that's an acceptable trade off compared to being fried like an egg in my cockpit.

On the lake where I normally keep my boat, there's some high voltage lines that cross the lake at one area.The lines are probably a good 60 ft.above the water.You can hear them "buzzing" before you get to them. From the water, to the top of my mast it's approx.~30 ft. I've noticed while sailing under the lines that if you touch anything steel on the boat, you get a slight tingling sensation from the inductance off the high voltage lines traveling through the mast, to the boat. Apparently the FRP is conductive enough to transmit this stray current to anything metal on the boat. My mast is stepped,and it really doesn't have a good path to the keel.I would think that having all these devices bonded together,and then attached to the keel ground path would help, not just in this scenario, but in a lighting strike also. Then again, we're talking about a surge of thousands of volts of electricity. On a much smaller scale, I've seen some 440 volt electrical panels short out, and it's not a pretty sight.

On a side note. I once almost witnessed what looked to be a sure death on the lake that I mentioned. I had sailed under the power lines when I saw a power boat pulling away from shore pulling a parasail. The operator of the boat was headed directly for the power lines, then he made a sharp 180 deg.turn. When the slack off the parasail line became taunt again, I heard a crack like a rifle shot. The parasail line had snapped,and the person on the parasail was headed directly for the power lines with the broken line dragging beneath them in the water. I thought, man, this is going to be like a big "bug zapper" if they get tangled up in the power lines. Luckily, the parasail drifted just beneath the lines. I'm sure a changing of clothing was in order for the parasail rider afterwards

Anyway, I would like to hear from some cruisers out there that have some of these LP systems installed on their boats. Are their winches, wheel pedestal,etc.,bonded to form a grid,and then tied back to the main ground conductor? From the book I mentioned, it seems one key to having an effective LP system is to have the ground conductor travel the shortest path possible, to the keel. Is this how your system is set up? Anyone have a boat with a grounding plate attached to the hull,with an external grounding conductor to it? How effective do you feel these systems are?

***I noticed that Gord had provided a very good link on this subject on another board.

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

[Troubledour]

Political Economy is the basis of all good government. The wisest
men of all ages have brought to bear upon this subject the--

[Here I was interrupted and informed that a stranger wished to see me
down at the door. I went and confronted him, and asked to know his
business, struggling all the time to keep a tight rein on my seething
political-economy ideas, and not let them break away from me or get
tangled in their harness. And privately I wished the stranger was in the
bottom of the canal with a cargo of wheat on top of him. I was all in a
fever, but he was cool. He said he was sorry to disturb me, but as he
was passing he noticed that I needed some lightning-rods. I said, "Yes,
yes--go on--what about it?" He said there was nothing about it, in
particular--nothing except that he would like to put them up for me.
I am new to housekeeping; have been used to hotels and boarding-houses
all my life. Like anybody else of similar experience, I try to appear
(to strangers) to be an old housekeeper; consequently I said in an
offhand way that I had been intending for some time to have six or eight
lightning-rods put up, but--The stranger started, and looked inquiringly
at me, but I was serene. I thought that if I chanced to make any
mistakes, he would not catch me by my countenance. He said he would
rather have my custom than any man's in town. I said, "All right," and
started off to wrestle with my great subject again, when he called me
back and said it would be necessary to know exactly how many "points" I
wanted put up, what parts of the house I wanted them on, and what quality
of rod I preferred. It was close quarters for a man not used to the
exigencies of housekeeping; but I went through creditably, and he
probably never suspected that I was a novice. I told him to put up eight
"points," and put them all on the roof, and use the best quality of rod.
He said he could furnish the "plain" article at 20 cents a foot;
"coppered," 25 cents; "zinc-plated spiral-twist," at 30 cents, that would
stop a streak of lightning any time, no matter where it was bound, and
"render its errand harmless and its further progress apocryphal." I said
apocryphal was no slouch of a word, emanating from the source it did,
but, philology aside, I liked the spiral-twist and would take that brand.
Then he said he could make two hundred and fifty feet answer; but to do
it right, and make the best job in town of it, and attract the admiration
of the just and the unjust alike, and compel all parties to say they
never saw a more symmetrical and hypothetical display of lightning-rods
since they were born, he supposed he really couldn't get along without
four hundred, though he was not vindictive, and trusted he was willing to
try. I said, go ahead and use four hundred, and make any kind of a job
he pleased out of it, but let me get back to my work. So I got rid of
him at last; and now, after half an hour spent in getting my train of
political-economy thoughts coupled together again, I am ready to go on
once more.]

richest treasures of their genius, their experience of life, and
their learning. The great lights of commercial jurisprudence,
international confraternity, and biological deviation, of all ages,
all civilizations, and all nationalities, from Zoroaster down to
Horace Greeley, have--

[Here I was interrupted again, and required to go down and confer further
with that lightning-rod man. I hurried off, boiling and surging with
prodigious thoughts wombed in words of such majesty that each one of them
was in itself a straggling procession of syllables that might be fifteen
minutes passing a given point, and once more I confronted him--he so calm
and sweet, I so hot and frenzied. He was standing in the contemplative
attitude of the Colossus of Rhodes, with one foot on my infant tuberose,
and the other among my pansies, his hands on his hips, his hat-brim
tilted forward, one eye shut and the other gazing critically and
admiringly in the direction of my principal chimney. He said now there
was a state of things to make a man glad to be alive; and added, "I leave
it to you if you ever saw anything more deliriously picturesque than
eight lightning-rods on one chimney?" I said I had no present
recollection of anything that transcended it. He said that in his
opinion nothing on earth but Niagara Falls was superior to it in the way
of natural scenery. All that was needed now, he verily believed, to make
my house a perfect balm to the eye, was to kind of touch up the other
chimneys a little, and thus "add to the generous 'coup d'oeil' a soothing
uniformity of achievement which would allay the excitement naturally
consequent upon the 'coup d'etat.'" I asked him if he learned to talk
out of a book, and if I could borrow it anywhere? He smiled pleasantly,
and said that his manner of speaking was not taught in books, and that
nothing but familiarity with lightning could enable a man to handle his
conversational style with impunity. He then figured up an estimate, and
said that about eight more rods scattered about my roof would about fix
me right, and he guessed five hundred feet of stuff would do it; and
added that the first eight had got a little the start of him, so to
speak, and used up a mere trifle of material more than he had calculated
on--a hundred feet or along there. I said I was in a dreadful hurry,
and I wished we could get this business permanently mapped out, so that I
could go on with my work. He said, "I could have put up those eight
rods, and marched off about my business--some men would have done it.
But no; I said to myself, this man is a stranger to me, and I will die
before I'll wrong him; there ain't lightning-rods enough on that house,
and for one I'll never stir out of my tracks till I've done as I would be
done by, and told him so. Stranger, my duty is accomplished; if the
recalcitrant and dephlogistic messenger of heaven strikes your--"
"There, now, there," I said, "put on the other eight--add five hundred
feet of spiral-twist--do anything and everything you want to do; but calm
your sufferings, and try to keep your feelings where you can reach them
with the dictionary. Meanwhile, if we understand each other now, I will
go to work again."

I think I have been sitting here a full hour this time, trying to get
back to where I was when my train of thought was broken up by the last
interruption; but I believe I have accomplished it at last, and may
venture to proceed again.]

wrestled with this great subject, and the greatest among them have
found it a worthy adversary, and one that always comes up fresh and
smiling after every throw. The great Confucius said that he would
rather be a profound political economist than chief of police.
Cicero frequently said that political economy was the grandest
consummation that the human mind was capable of consuming; and even
our own Greeley had said vaguely but forcibly that "Political--

[Here the lightning-rod man sent up another call for me. I went down in
a state of mind bordering on impatience. He said he would rather have
died than interrupt me, but when he was employed to do a job, and that
job was expected to be done in a clean, workmanlike manner, and when it
was finished and fatigue urged him to seek the rest and recreation he
stood so much in need of, and he was about to do it, but looked up and
saw at a glance that all the calculations had been a little out, and if a
thunder-storm were to come up, and that house, which he felt a personal
interest in, stood there with nothing on earth to protect it but sixteen
lightning-rods--"Let us have peace!" I shrieked. "Put up a hundred and
fifty! Put some on the kitchen! Put a dozen on the barn! Put a couple
on the cow! Put one on the cook!--scatter them all over the persecuted
place till it looks like a zinc-plated, spiral-twisted, silver-mounted
canebrake! Move! Use up all the material you can get your hands on, and
when you run out of lightning-rods put up ramrods, cam-rods, stair-rods,
piston-rods--anything that will pander to your dismal appetite for
artificial scenery, and bring respite to my raging brain and healing to
my lacerated soul!" Wholly unmoved--further than to smile sweetly--this
iron being simply turned back his wrist-bands daintily, and said he would
now proceed to hump himself. Well, all that was nearly three hours ago.
It is questionable whether I am calm enough yet to write on the noble
theme of political economy, but I cannot resist the desire to try, for it
is the one subject that is nearest to my heart and dearest to my brain of
all this world's philosophy.]

economy is heaven's best boon to man." When the loose but gifted
Byron lay in his Venetian exile he observed that, if it could be
granted him to go back and live his misspent life over again, he
would give his lucid and unintoxicated intervals to the composition,
not of frivolous rhymes, but of essays upon political economy.
Washington loved this exquisite science; such names as Baker,
Beckwith, Judson, Smith, are imperishably linked with it; and even
imperial Homer, in the ninth book of the Iliad, has said:

Fiat justitia, ruat coelum,
Post mortem unum, ante bellum,
Hic facet hoc, ex-parte res,
Politicum e-conomico est.

The grandeur of these conceptions of the old poet, together with the
felicity of the wording which clothes them, and the sublimity of the
imagery whereby they are illustrated, have singled out that stanza,
and made it more celebrated than any that ever--

["Now, not a word out of you--not a single word. Just state your bill
and relapse into impenetrable silence for ever and ever on these
premises. Nine hundred, dollars? Is that all? This check for the
amount will be honored at any respectable bank in America. What is that
multitude of people gathered in the street for? How?--'looking at the
lightning-rods!' Bless my life, did they never see any lightning-rods
before? Never saw 'such a stack of them on one establishment,' did I
understand you to say? I will step down and critically observe this
popular ebullition of ignorance."]

THREE DAYS LATER.--We are all about worn out. For four-and-twenty hours
our bristling premises were the talk and wonder of the town. The
theaters languished, for their happiest scenic inventions were tame and
commonplace compared with my lightning-rods. Our street was blocked
night and day with spectators, and among them were many who came from
the country to see. It was a blessed relief on the second day when a
thunderstorm came up and the lightning began to "go for" my house, as the
historian Josephus quaintly phrases it. It cleared the galleries, so to
speak. In five minutes there was not a spectator within half a mile of
my place; but all the high houses about that distance away were full,
windows, roof, and all. And well they might be, for all the falling
stars and Fourth-of-July fireworks of a generation, put together and
rained down simultaneously out of heaven in one brilliant shower upon one
helpless roof, would not have any advantage of the pyrotechnic display
that was making my house so magnificently conspicuous in the general
gloom of the storm.

By actual count, the lightning struck at my establishment seven
hundred and sixty-four times in forty minutes, but tripped on one of
those faithful rods every time, and slid down the spiral-twist and shot
into the earth before it probably had time to be surprised at the way the
thing was done. And through all that bombardment only one patch of slates
was ripped up, and that was because, for a single instant, the rods in
the vicinity were transporting all the lightning they could possibly
accommodate. Well, nothing was ever seen like it since the world began.
For one whole day and night not a member of my family stuck his head out
of the window but he got the hair snatched off it as smooth as a
billiard-ball; and; if the reader will believe me, not one of us ever
dreamt of stirring abroad. But at last the awful siege came to an
end-because there was absolutely no more electricity left in the clouds
above us within grappling distance of my insatiable rods. Then I sallied
forth, and gathered daring workmen together, and not a bite or a nap did
we take till the premises were utterly stripped of all their terrific
armament except just three rods on the house, one on the kitchen, and one
on the barn--and, behold, these remain there even unto this day. And
then, and not till then, the people ventured to use our street again.
I will remark here, in passing, that during that fearful time I did not
continue my essay upon political economy. I am not even yet settled
enough in nerve and brain to resume it.

TO WHOM IT MAY CONCERN.--Parties having need of three thousand two
hundred and eleven feet of best quality zinc-plated spiral-twist
lightning-rod stuff, and sixteen hundred and thirty-one silver-tipped
points, all in tolerable repair (and, although much worn by use, still
equal to any ordinary emergency), can hear of a bargains by addressing
the publisher.


-THE END-
[Samuel Clemens] Mark Twain's short story: Political Economy

[BC Mike]

The reason lightning never strikes the same place twice is because the place where it hit the first time is not there anymore. Lightning put a hole in an underground gas line which filled the basement of a house which later exploded killing the two residents. Our mast is grounded to the keel, it was a factory option so I ticked the box. We were anchored one night and the rigging started to humm and drone, it would rise and fall in volume as the charge around us increased. Lightning hit about 1/4 mile away and the photo is on a photographers business card. Lightning hit a tree about 15 miles to the South West of us this summer and the resulting fire roasted the entire South slopes and more plus 243 homes. The fire lasted for a long time. Our house was hit in NZ many years ago. I am trying to avoid the stuff. I put on shoes if I am barefoot on the boat and suddenly become religous. BC Mike C