|Topic Review (Newest First)|
|05-05-2009 12:33 AM|
|Hudsonian||Many years ago a friend and his new trophy wife flew to Florida to sail a newly purchased Freedom 40 back to the Hudson; a remarkable venture for their honeymoon since she had never been on a sailboat before. Some time later we found ourselves sharing a little anchorage by Bannerman's Island with the couple aboard their Freedom 40. Delighted to see them again, I asked how their journey had gone and was informed that en route they had been struck by lightning twice -- losing a mast with each strike. When I expressed my concern and asked the lovely bride what she thought after the second strike, she responded, "I didn't think much about it. After all, after the first strike I just thought it was part of sailing.'|
|05-04-2009 11:54 PM|
|NICHOLSON58||I raced on a Cal 40 in the 70's that was struck in its slip late at night. An observer on another boat saw a ball travel down the mast and light up the cabin before it disipated. He watched for a while and didn't notice any issues but the electricity melted the nylon bushing around the depth trasducer and the boat sunk in its slip. The boat bottom was polished graphite and the keel was solid lead.|
|04-05-2009 12:40 PM|
|CaptainForce||I enjoyed reading Depthwish's account of the fuses shooting out like bullets. I noticed the same phenomenon in the late seventies on a boat that had been struck. In this case bus fuses had shot accross the nav station leaving pock marks in the opposite bulkhead. I've seen a number of strikes, but only a nearby strike myself that had no effect other than showing 88 messages on my answering machine. It is difficult to evaluate the effectiveness of protection devices as there is such great variety in the instensity of strikes and the resulting damage. Unfortunately, and in common with so many other bad interpretations of scientific data, people give to much credit to annecdotal advice. 'reminds me of my contrary witted friends that won't wear a seatbelt because they heard of some guy that was thrown from the vehicle as the onlly survivor. 'take care and joy, Aythya crew|
|04-04-2009 07:51 PM|
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".
|03-23-2009 12:36 AM|
Lightning Protection Systems & Strikeshield system product
Originally Posted by GordMay View Post
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.
|04-11-2006 04:45 PM|
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.
|04-10-2006 02:18 AM|
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!
|04-06-2006 10:16 PM|
|sailnaway||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.|
|03-21-2006 08:29 PM|
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.
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.
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.
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.
|03-19-2006 09:19 PM|
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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