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Lightning

 
 
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Old 04-22-2009, 01:31 PM   #16 (permalink)
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Originally Posted by CaptEvan
Thanks Tom, not only for the well done piece but going through the effort to share it.
You're welcome. Hope the info helps out.
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Old 04-24-2009, 08:28 PM   #17 (permalink)
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Storm scope or Strike finder use?

Do boats use Storm scopes ie lightning sensing systems? Reading the tales of lightning strikes got me wondering if anybody uses or has used these devices to minimize exposure?

Steve
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Old 04-24-2009, 09:21 PM   #18 (permalink)
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Not sure about Storm scopes on boats.

On airplanes yes, because you are fast enough to fly away from a thunderstorm if you see one on the scope while IFR.

On a boat you will see it visually in day-time and see the lightening at night and can try to run.
If you get caught in a squall on the water, the storm scope may not help anyway..(Too late)

Perhaps the more experienced Captains on this here board have a different opinion on the Storm Scope..?
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Old 04-25-2009, 04:47 AM   #19 (permalink)
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Lightning

We were hit last fall while at the dock in our home port of Fort Lauderdale. Our boat has a sophisticated lightning arrestor at the high point of our antenna mast with a heavy cable leading to a massive ground plate in the hull.

Most systems were shut down at the time, including the MTU controls. It is the engineer's practice to shut down the breakers to the MTU's as well when in port. I had one of the flat screen monitors, the gyro, one depth sounder, and the AIS running. Also running was one of two SeaTel TV antennas.

All of the items that were swicthed on were damaged and had to repaired or replaced. Also, all three VHFs, which were off, had to be replaced. Most of the other systems seem to be OK, including the MTU controls.

In the future when I find myself caught out in an active lightning storm, I think that I will switch off my secondary and back up systems ie; one radar, second GPS and screens etc in order to preserve some use of the systems if we get hit again.

Capt Dave - M/Y KIPANY
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Old 04-25-2009, 02:54 PM   #20 (permalink)
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Sirius Weather shows lightning strikes, but in a bad storm, a Raymarine G-Series' whole screen is peppered over with bolt symbols. So putting the weather system in motion, you can rest assured the sky welder is coming. Whether you can get out of it's way is a question of your max planing speed and the girth of your cajones.

On Furuno's latest system, you can see when/where a strike occurred, and it will delete itself after a predetermined time frame. So as it approaches, you can watch the electrical activity increase/decrease.
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Old 04-25-2009, 03:08 PM   #21 (permalink)
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You have 21 computers on board!?
Sorry Capt. Bill for not responding to your question. The Volvo IPS triple engine system on the boat had 19, and we added 2 of our own. Come to think of it, the G-Series has a few more, so we might have been 25 plus.

When I inquired, at a Volvo IPS training session, of the ability to get an engine running after a lightning strike 30 miles out, the instructor gave the canoe paddling motion. But with fuel delivery in most current engines controlled by printed circuits, baling wire and duct tape simply will not get you home anymore.
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Old 09-02-2010, 04:28 AM   #22 (permalink)
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Lightning strike on yacht

This summer a strong storm with heavy rain in Altea (Spain)...
http://www.youtube.com/watch?v=zPZpnUZoWNI
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Old 09-02-2010, 05:28 AM   #23 (permalink)
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That's why I love sailboats (not to be in, but to have around in a storm).
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Old 09-02-2010, 09:40 PM   #24 (permalink)
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I have been hit by lightning twice on a delivery of a 44' Lagoon from France to Annapolis. I was at the Flying Bridge about 4 meter from the mast foot (shouldn't have been there in hindsight) and one of my crew was lying on the couch in the saloon looking outside trough a roof hatch.

We knew we were going to be hit becouse the lightning had surrounded us and was closing in on us. When it finally hit I fended my eyes of and heard a loud bang with white light. The crew member lying on the couch remembers seeing the lightning hitting the mast. This happend twice that night and our only damage was the VHF antenna.
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Old 09-03-2010, 03:52 PM   #25 (permalink)
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no one can figure out lighting....maybe 50% fact,50% guesswork....we where hit in MD.one summer and i spent the next 9 years researching and talking to other victims...found out nothing that could be put in stone,except be lucky........examples...2 same type small boats,on different occasions,where hit in palm beach inlet...#1,all safe,but burnt a little...#2,all dead...............a small sportfish,w/very short riggers,docked between two large sailboats at elbow key..he gets hit in his searchlight,wipes out his electronics,and no one else has any sign of a hit..........riding back from west end in the worst lighting storm..antennas and long outriggers..we can see lighting hitting the water many times very close, but it never hit us ????? be lucky
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Old 09-03-2010, 04:40 PM   #26 (permalink)
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no one can figure out lighting....maybe 50% fact,50% guesswork....we where hit in MD.one summer and i spent the next 9 years researching and talking to other victims...found out nothing that could be put in stone,except be lucky........examples...2 same type small boats,on different occasions,where hit in palm beach inlet...#1,all safe,but burnt a little...#2,all dead...............a small sportfish,w/very short riggers,docked between two large sailboats at elbow key..he gets hit in his searchlight,wipes out his electronics,and no one else has any sign of a hit..........riding back from west end in the worst lighting storm..antennas and long outriggers..we can see lighting hitting the water many times very close, but it never hit us ????? be lucky
There's no ryhme or reason. Except certain boats seem to attract it more then others. I know of 2 sportfish that were both hit 3 different times. 1 of them docked in a crowded marina with other tall antannae's and metal structures all around it, yet it got hit 3 different times over a few years. Don't know why, but none of the other boats or the fuel dock and it's equally tall metal sign never got hit. Maybe the electrical field a combination of a yachts metal and electronics attract it, I don't know.
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Old 09-04-2010, 09:10 AM   #27 (permalink)
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The aviation industry has been dealing with this issue for some time. If an aircraft with a FADEC (full authority digital electronic control) on the engines were to be hit by lightning, things would go quite, and in an airplane that's a "very bad thing".

Do a search on HIRF and HIRF/L protection and you will see how this is done with aircraft.

Basically what is done is each piece of electronics is "hardened" by putting it into a box that is grounded and has no holes in it. All of the cabling is shielded and the shielding is grounded and the cabling connectors are metal and are grounded to the shielding and the case. Lengths of cabing that are not shielded and grounded act like antennas and pick up the lightning, so you don't want unshielded runs of cable anywhere in the boat.

It can be done, the radios and electronics in aircraft are hardended, but it is expensive and since it happens infrequently and the effects aren't usually life threatening, electronics in boats aren't hardended. There is testing that can be done, and the FAA and the military have standards for the protection of hardware, but as I've said it costs a lot to make the hardware hardended, and the engineering and testing aren't cheap either.

My concern would be with electronic engine controls. A lightning strike would leave you dead in the water and when you are offshore, that's just a bad place to be.
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Old 09-04-2010, 03:47 PM   #28 (permalink)
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There was an excellent article in PassageMaker magazine recently about lightning. It describes a new system being installed on a 40 ft boat which routes the charge down to a series of discharge ports along the water line of the boat. {Very similar to static wicks on an aircraft}
I don't have the info with me but a check of PassageMaker online might bring up the article.

Cheers
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Old 09-04-2010, 09:05 PM   #29 (permalink)
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Quote:
Originally Posted by islandmech
There was an excellent article in PassageMaker magazine recently about lightning. It describes a new system being installed on a 40 ft boat which routes the charge down to a series of discharge ports along the water line of the boat. {Very similar to static wicks on an aircraft}
I don't have the info with me but a check of PassageMaker online might bring up the article.
It was the July/August 2010 issue on pages 44 to 53. The company mentioned is Marine Lightning Protection - http://www.marinelightning.com.
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Old 10-01-2011, 04:27 AM   #30 (permalink)
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Ouch! Even well sealed concrete will hold some moisture. If the lightning charge accessed the wire mesh there would be substantial heat generated. Or am I just imagining a ridiculously remote worst case?
to my knowlegde it is like a lightning strike on a tree. the sap vaporizes and expands instantainously causing the tree to explode.

As the concrete holds moisture it has same effect - vaporises, expands, explodes (when structure fails to withstand the pressure).

My question would be "what is the effect on a steel hull boat with a alloy mast"

I know the mast would melt but
the discharge to the lowest potiental and
what path it would take,
along with how well earthed you are inside all would affect whether you get fried or not?

I dont know....
I would be interested if any1 had a answer to
will you get fried in a steel hull boat or will the water act as a strong enough insulator to allow survival?
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