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Go Back   SailNet Community > Out There > Cruising & Liveaboard Forum > Living Aboard
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  #21  
Old 03-25-2005
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Lightning Anyone?

In the summer of 2004 we were in St Pete Florida the capitol of lightning strikes. I had pulled into the Municipal Harbor to the cleanout station and a squal had come in. I was at the wheel and just stood off the dock waiting for the rain and wind to pass. KABOOOOM! my wife was looking out of the companion way at me when it hit. I had just at the exact second turned and without thinking grabbed the back stay to steady myself.It struck a boat shed about twenty yards astern but the branches must have jumped off and hit us. It burned my bare feet and the palm of my hand which was on the backstay. I was not sure if I had ahold of the wheel to or not as I was just sitting at idle.The burns were very minor,the electronics was fried. Every thing on the boat with a printed circuit was zapped and dead or only worked part way. Clock radio had no display but the radio worked. Tv zapped all wind insterments,depth speed ect zapped. Some of the stuff was not plugged in and was still fried.The only possible reason that I was not killed may have been this.We had been in the anchorage and when we pulled the hook a plow it came up with a big wad of mud. Since we were only going agout a mile arount the Pier at St Pete we left the anchor hanging down with maybe six feet of chain from the chock to the shank so the mud would wash off. That could have disipated some of the charge off.I talked to some Navy electronic survalance guys and ask about this and they said that they had hung plates in the water attached to ship masts from chains to take the charge away from the ship. I am thinking about some stainless chain and a couple of round plates so I can just use a d rind to attach them to the stays on both sides of the mast. I am thinking a circle of about 18inches across on a piece of chain long enouhg to get the plate at the same depth as the led or cast iron keel. a piece of thin wall clear plastic tube to keep the chain off the hull. This may or may not help but it makes it a little more grounded.Boats in salt water get hit less than boats in fresh water was something I found out. I don''t know how much being plugged into shore power helps if at all. I worked on a three story house in Colorado quite a few years back as a plumbing contractor. The lightning had struck th roof above the peoples daughters bed. It blew a three foot hole through the roof through the bed went through the floor lifting the hard wood about three inches hit the copper plumbing and blew the fixtures off the wall in two bathrooms ruptured the hotwater tank in the garage and set the place on fire. No one was home luckey for them becaause the daughter spent allot of time sitting on the bed yacking to her gitlfriends on the phone that was melted on a night stand.
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  #22  
Old 04-01-2005
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rangerrobinfl is on a distinguished road
Lightning Anyone?

I was hit while connected to shore power last week on Gasparilla Island. My 30 amp breaker popped but the vhf antenna cable fried as well as the inverter on my fridge, GPS, anchor and steaming lights and breakers, and solar panel charge controller. I was probably lucky and that is good.

Rob
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  #23  
Old 04-06-2005
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Lightning Anyone?

My 02.
I''ve lived in Florida 56 yrs and on sailboats 10+ along the ICW. Seen many boats struck and talked to people who were onboard or near during the strike. Boats I''ve looked at have had their aluminun masts melted and fiberglass hulls blown to pieces and sunk. Others were everything else from standing rigging bolts punched out to St Elmo''s Fire and no damage. The ones with "grounding wires" hanging into the water from a stay survived way better than those without...always.

When you get hit and it only takes out electronics it is a "feeder" strike. Study the numbers and you will see nothing survives a strike by the main bolt. It blows or melts everything from too much pressure or heat. The is no practical way to conduct that much juice to prevent damage.

The only thing you can do is bleed static charge away and prevent attraction. The highest point will be struck if charged more than the surrounding areas. I put a handheld miliamp meter on an aluminum mast. Everytime the wind gusted the needle pegged showing static charge. The static bled off faster with a grounding wire clamped to the stay and dropped in the water compared to nothing in the water. Anyone can do this test on their own boat to see. An old electrical contractor/sailor showed me this. He did mostly high voltage and lightning protection for buildings and farms.
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  #24  
Old 03-19-2006
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The real reasons to bond the mast, stays, shrouds, and chainplates is to: 1)provide a protective cage for the crew to stay inside; 2) help prevent side flashes, where the current from the lightning bolt jumps laterally between to large metal components and injures or kills anyone standing in the way.

The DC grounding and bonding system for the electronics and through hulls should be separate from the lightning grounding system.
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  #25  
Old 03-21-2006
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depthwish is on a distinguished road
shocking.experience

sorry.for.the.periods.again.no.spacebar.
yes.I.was.struck.by.lightning.off.of.chicago.about .2.years.ago.
we.came.through.a.squall.trying.to.get.in.and.were .faced.with.a.horizon.that.was.black.as.coal.
I.sent.everyone.down.below.and.put.on.my.foul.weat her.gear.
I.think.we.were.lucky.that.the.boat.was.wet.as.it. spread.the.hit.over.a.larger.space.
It.basically.blasted.my.hands.off.the.wheel.a nd.when.I.could.hear.again.I.was.so.glad.to.hear.m y.atomic.4.engine.still.running.
We.lost.all.the.electronics.and.anything.plugged.i nto.the.shore.power.110.system.
At.first.I.thought.it.was.a.near.miss.as.I.saw.the .flash.about.20.yards.off.the.starboard.beam.
I.later.learned.that.the.masthead.was.struck.and.t he.bolt.travelled.down.the.starboard.topshroud.and .when.it.got.to.the.imbedded.
chainplate.spat.out.the.hull.leaving.about.a.5.inc h.circle.of.delamination.and.a.pellet.sized.hole.o ut.the.hull.of.the.boat.
Since.then.I.have.read.up.some.and.asked.some.ques tions.
1...you.need.a.good.ground.from.your.standing.rigg ing.and.your.mast.and.the.water.whether.it.is.a.pl ate.on.the.hull.a.direct.connection.
to.an.external.keel.or.(in.my.case).4.10.foot.leng ths.of.1/4.inch.chain.and.a.quicklink.which.I.hang.off.of.t he.shrouds.on.both.sides.so.if.I.am.
under.sail.I.have.4.points.of.ground.into.the.wate r.on.both.tacks.
it.deploys.quickly.you.can.have.it.set.up.within.5 .minutes.of.spotting.foul.weather.
2...as.for.the.electronics.good.luck.I.have.instal led.inline.fuses.on.a.lot.of.stuff.and.set.up.two. separate.fuse.blocks.for.everything.but.
as.I.understand.it.with.lightning.it.can.jump.righ t.across.the.fuse.block.without.even.noticing.it.h as.blown.the.fuse.
I.know.in.my.case.the.old.style.socket.fuseholders .on.my.boat.were.blown.into.the.engine.compartment .like.little.22.bullet.
I.highly.recommend.a.hand.held.vhf.on.board.as.it. may.be.the.only.communication.you.have.after.a.str ike.

""lightning.never.strikes.the.same.place.twice....to o.bad.I.moved.my.boat""
Eric.Branson
"Zarathustra"
Islander.37
Chicago.Il.
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Old 04-06-2006
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While waiting for a squal to pass up in St pete I was at the pump out at the City Marina. I stood at the wheel raining like hell and boom. We were struck it stunned me burned my hand that I had used to grab the back staw to steady myself as I turned to look over my sholder to see where the boat shed behind me was.We lost all our electronics and some things that were sitting on the shelf and were not plugged in. Well the good thing is I am alive. We had our anchor hanging on about five feet of chain to wash the mud off which may have taken some of the current away.
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Old 04-10-2006
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A couple of years ago we were on our way home from Cape Breton's Bras d'Or Lakes in the middle of St. Georges Bay about 12 miles from any land when the sky darkened up REAL fast and we doused sail and fired up the engine to prepare as best we could for the fireworks display which we were sure was imminent. A bolt shot from cloud-to-cloud directly above the mast on our Aloha 27. Never have I been so close as to smell ozone and I'm in no hurry to repeat the experience.

Just remember... if you see the lightning bolt- it missed you!
__________________
Steve, Patti and Grace (Ship's Cat)
sv "Ever After"
Barrachois Harbour
NS Canada

Last edited by Aloha27; 04-11-2006 at 12:39 AM.
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  #28  
Old 04-11-2006
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You will find many opinions, contradictory "studies", and no one set of rules for how to protect against lightning or mitigate the damage from it. The bottom line is that when a jillion volts decides to come calling, there is NO way to be absolutely certain of what it will do on your boat, no matter how it is rigged. Because it can jump, or induce currents, or create plasma balls, your best bet is to do some serious work on creating a good direct ground path (down the mast and into the water) and then learn that when the gods are bowling, you need to be ashore and indoors. Or, curled in a ball as far away from all metal parts of the boat as you can.

Very few things scare me the way the brute force of lightning does, and that's after reading all the opinions and studies. If you've ever been on a boat and felt your hair standing on end and heard static crackling off your radio antenna...."lightning protection" becomes a very remote concept.
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Old 03-22-2009
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Garymatson is on a distinguished road
Lightning Protection Systems & Strikeshield system product

Quote:
Originally Posted by GordMay View Post
See "Lightning & Sailboats" by Ewen M. Thompson.
Sea Grant Project #R/MI-10
Lots of other good web sources are searchable.
Bottom line: BOND EVERYTHING.
Good Luck
Gord
-------------
The link to the Florida University & the lightning research that was created still exists and is really, really helpful to read. (its brief & non technical).

I also just completed a US Power Squadron course on marine electronics which had one brief, but informative, chapter on lightning PROTECTION SYSTEMS. You can't stop a lightning strike but you CAN install a 'system' that provides 99% protection under a "cone." Its a three part system.... all really simple to understand... that works in conjunction with a fourth part called grounding which runs horizontal bow to stern.

The "strikeshield lightning protection system" is a commercial retail after market product that is attached to one's sailboat. I was doing some reading on it. The problem is: it seems to contradict the information from the US Power Squadron text. That is, the conductor running down the mast isn't supposed to jut sideways out over the deck. Lightning wants to do directly downward to ground and if you don't provide a low resistance path, it simply archs or jumps off the path to the path it wants to follow. Right angle turns of the after market system don't seem to be as safe as they imply.

Anyone know of any lightning strikes upon boats using that after market system? I'd bet its better than nothing, but I'm not yet convinced.
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Old 04-04-2009
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I was on the ICW in NC when I was struck while at anchor. Blew the mastead light and VHF aerial off the masthead and burned out some random electronics below decks. However there was another effect which I did not find out about till I left the anchorage. My steel boat was now a strong magnet and my compass read due east regardless of heading.

Took a very kind naval compass adjustor a day to drive out the "Bad Spirits".
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