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Old 11-10-2016, 22:31   #1
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Lightning Strike! Whats the likely damage and preventive measures.

In an electrical storm, can i run a heavy wire cable up the mast and have the other end in the water. If im leaving the boat unattended what else can i do. Whats gets damaged.
I will now thank you in advance. Thanks.
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Old 12-10-2016, 01:37   #2
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Lightning seems to be fickle & unpredictable about what boats it chooses to strike, & what it harms when it strikes. As on some boats there's virtually no damage, & on others it fries everything electrical, in addition to doing severe damage to the boat & rig. This occurs somewhat without regard to the steps that we take to mitigate the damage, not that prepping things isn't wise.

Probably the most consistent things to do are to shut off, & disconnect everything electrical that you can. Especially electronics. So that hopefully the lightning will miss them as it seeks a path to ground. Though side flashes are common, as are other concurrent high energy electrical events. But if things are disconnected they have a better chance of surviving.

In addition to the above, many people will take some of their electronics & place them into an improvised farady cage inside of the boat, such as the oven. Hopefully after isolating them electrically, so that they're not directly in contact with the cage/oven.

With regard to further prep, since you'll be away from the boat, it can't hurt to have your emergency contact information posted inside of her, perhaps at the nav desk. As well as at the marina office of course. And since lightning does sometimes harm through hulls, or create small holes in the hull, you might draw up a sketch of the boat which details specifically where all of her skin fittings are, & what they're for. And post it at the nav desk too. Along with some spare emergency plugs, to supplement the ones which are next to each fitting below the WL.
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Old 12-10-2016, 02:00   #3
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Yes, ive often wondered about the Faraday oven trick, i heard at 180 for 45 mins is best.
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Old 17-10-2016, 05:28   #4
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Prevention - read this link. Apparently you should have a mono, be berthed in a marina and parked next to a cat with a mast taller than yours And don't have your shore power connected.

Cheers Manawatuman - I'm PN born and raised

Lightning Facts: An Analysis of Lightning Strikes >> Scuttlebutt Sailing News
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Old 17-10-2016, 05:40   #5
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pirate Re: Lightning Strike! Whats the likely damage and preventive measures.

The old method was to shackle lengths of chain just long enough to swing below the water surface to each of the mast stays.. the idea being to conduit the strike on past the decks on into the water.
Mind you.. this was for mono's when the stays went to the outer hull or just inside the toerail.. for a cat..???
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Old 17-10-2016, 05:43   #6
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Lol. Cheers MumnDad. You sound like a Awatapu boy....
Sounds like not much we can do except keep the gumboots on
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Old 17-10-2016, 05:54   #7
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Quote:
Originally Posted by boatman61 View Post
The old method was to shackle lengths of chain just long enough to swing below the water surface to each of the mast stays.. the idea being to conduit the strike on past the decks on into the water.
Mind you.. this was for mono's when the stays went to the outer hull or just inside the toerail.. for a cat..???
Never seen any boats rigged like that. What do you recommend - Do you wait 'til a storm strikes then rush out with your gumboots(wellys) on to clip stuff to the rigging?
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Old 17-10-2016, 05:59   #8
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Could be very noisy in the mono with chains hanging, maybe permanent insulated HT lead from a copper spire to the water.

Dislexics are teople poo
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Old 17-10-2016, 06:02   #9
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Re: Lightning Strike! Whats the likely damage and preventive measures.

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Originally Posted by manawatuman View Post
Lol. Cheers MumnDad. You sound like a Awatapu boy....
Sounds like not much we can do except keep the gumboots on
Nearby - Park Road raised but Awatapu didn't exist in my day PNBH
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Old 17-10-2016, 06:18   #10
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pirate Re: Lightning Strike! Whats the likely damage and preventive measures.

Quote:
Originally Posted by DumnMad View Post
Never seen any boats rigged like that. What do you recommend - Do you wait 'til a storm strikes then rush out with your gumboots(wellys) on to clip stuff to the rigging?
Ahahahahaaa.... One generally gets advanced warning if one lives aboard.. darkening sky.. distant flashes and approaching thunder... if your in a place for a while, nothing to stop you leaving them dangling till you move on, just rig em when you arrive.
If your somewhere like Beaufort NC where I've experienced some awesome lightening storms on the hook in Taylors Creek maybe not a bad idea.
I did most of my early sailing in the UK (1st boat was timber plank) and it was pretty common on the wooden boats back in the 60's.. plastic fantastics and ally masts were scarce and don't seem to have the same attraction as timber.. why dya think they say.. never shelter under a tree.??

PS.. worried about noise sleeve the chain.
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Old 17-10-2016, 06:19   #11
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Re: Lightning Strike! Whats the likely damage and preventive measures.

A friend of mine's Passport 40 was hit by lightning. Fried pretty much every single electrical device on the boat...even the lenses on his deck level running lights were blown out. Had to replace the forestay, foil and sail as the jib was charred where the current leapt from foil section to foil section.

True worst case is hole/leak blown in the bottom of the boat. Certainly the Passport was fully bonded and I suspect that helps to mitigate that possibility.

Best form of protection? A good insurance policy.
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Old 17-10-2016, 06:23   #12
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pirate Re: Lightning Strike! Whats the likely damage and preventive measures.

Quote:
Originally Posted by manawatuman View Post
Could be very noisy in the mono with chains hanging, maybe permanent insulated HT lead from a copper spire to the water.

Dislexics are teople poo
Lightening rod with cable running down to keel was standard
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Old 17-10-2016, 06:27   #13
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Quote:
Originally Posted by DumnMad View Post
Apparently you should have a mono, be berthed in a marina and parked next to a cat with a mast taller than yours
These would probably help but as noted, lightening is fickle. I had a friend that owned a 26' mono. He was one of the smallest boats in the marina which included a couple of cats. His boat was struck twice about a year apart with all those nice, juicy targets all around.

I put it down to divine retribution for his profligate life.
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Old 17-10-2016, 06:30   #14
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pirate Re: Lightning Strike! Whats the likely damage and preventive measures.

When Benjamin Franklin invented the lightning rod in 1750, he noted that it could also be used to protect ships. It was not long before the first ships were to benefit from his ideas.* In the late 18th century the sailing warships of the British navy were fitted with lengths of anchor chain to prevent their wooden masts from splintering when struck by lightning.* Franklin himself was unsure of the actual mechanism, thinking initially that a pointed rod would discharge the thunderstorm "for if there be a rod sharpened ... the electrical fire would be drawn out of a cloud" but five years later covering all bases by adding "pointed rods would either* prevent a stroke or would conduct it so that the building should suffer no damage".** For whatever reason, this technology worked.* The discharge physics of the* lightning strike to ground would not be well understood until research done in South Africa in the 1930's and later.
In the intervening centuries scientific opinion has come down squarely on the side of Franklin's last opinion - that a lightning rod protects a building by offering a suitable path for the current to flow.* Still, modern day refinements for marine protection somewhat mirror the historical record.* Although a code developed by ABYC definitely improves lightning safety, research continues into the underlying science.* In* a paper published by IEEE (the Institute of Electrical and Electronic Engineers) in 1991, Ewen Thomson of the University of Florida tested this code by applying the traditional science used in lightning protection systems for ground installations.* The traditional science, reflected in terms such as "ground resistance" and "step potentials" models voltage gradients as a consequence of current flow in the ground (or water). Thomson concluded that key changes were needed. While some changes were trivial to implement, such as upgrading down conductors from #8 gauge copper to #4 gauge copper, others were highly impractical.* In particular, Thomson noted that hull damage to sailboats struck in fresh water was so extensive, even when the boat had a good connection to the keel, that multiple grounding surfaces were needed over an extensive underwater area, a requirement is very difficult to fulfill in practice.
Of even more concern were some types of boat lightning damage that were impossible to explain with the traditional scientific model. In the light of these inconsistencies, Dr. Thomson concluded, in a yet unpublished study, that key assumptions in the traditional model were invalid* Removing these assumptions and reinterpreting the fundamental science has resulted in a new model that enabled innovative technology to be developed to overcome the above practical limitations.* This technology is now covered by a* patent issued by the University of Florida* and licensed solely to Marine Lightning Protection Inc.
Attachment
Since there is no scientifically proven method to repel it, the fundamental problem in yacht lightning protection is how to deal with lightning when it strikes.* Where the lightning channel attaches to a boat is determined by the geometry of topside conductors on the boat and the location of the downward-going stepped leader relative to the boat.* For example, if the stepped leader is heading for the water behind the boat, aft conductors are more likely to be struck.* In general, the taller the conductor, the higher the probability that its upward streamer will be the one that connects with the stepped leader, thereby completing the ground channel for the lightning. The conductor in the lightning protection system intended to make this connection is termed the air terminal, or, more commonly, the lightning rod.* In this respect, research reported by Dr. Charles Moore and associates in New Mexico only two years ago finally resolved that blunt lightning rods are actually more effective than the traditional sharp pointed rods. The tendency of a tall conductor to attract the lightning strike, by preferentially launching the final connecting streamer, has resulted in the idea of a "cone of protection".* This somewhat flawed idea holds that a vertical conductor forms an effective cone of protection, the apex of the 90 degree cone being at the top of the conductor, and protects the circular area of the cone's base. The idea is flawed in that a vertical conductor does not eliminate the electric field on the ground within this "protected" circular area.* Any conductors inside the area, people included, may give rise to upward streamers if this electric field reaches breakdown strength.* A better arrangement is to have conductors arranged around the area to be protected, or, better yet, forming an umbrella overhead, where the outer edges of the umbrella are connected to down conductors leading towards the water.
Hence the major concern regarding the lightning attachment is to ensure that the lightning attaches to, and causes current to flow in, only an air terminal, or other termination conductors, rather than more vulnerable conductors such as crew members, electronics, etc.
Charge dissipation into the water
Fiberglass is such a good insulator that it is used to make insulators for high voltage installations.* Nevertheless, the lightning voltage is more than enough to cause electrical breakdown through a fiberglass hull if no alternative path is provided, and frequently even if one is.* Each penetration leaves a charred hole and much more extensive internal damage.* Grounding conductors (electrodes) are intended to form a bridge into the water to eliminate this hull damage.* However, a single ground plate is inadequate to prevent sideflashes, necessitating multiple interconnected conductors.* These cause a whole new set of problems:
accelerated galvanic corrosion or loss of sacrificial zinc's;
electrolytic erosion in marinas with ground currents leakage;
many mounting bolts and hull penetrations, each one raising the risk of water seepage;
additional drag since plates should have exposed edges.
Through-hull transducers, fittings, and all immersed metal, including outboard drives, also inadvertently act as lightning grounds.* A typical scenario for an ungrounded smaller powerboat, such as a 20' fisherman, is for lightning to attach to the VHF antenna (vaporizing it), spark through the electronics panel (destroying all electronics), travel* into the battery ground or control cables into the outboard solid state ignition (rendering it inoperable), and then spark into the water through the drive unit. Any transducer such as a knotmeter is also likely to be blown out, possibly leaving a hole where it was mounted.* This scenario assumes that no crew member is unlucky enough to be bridging a gap along the way.
Carbon deposits after lightning strikes* trace out the paths followed by sparks forming from immersed conductors, both those grounded and those* that are isolated.* A detailed discussion of this effect is given in a *letter* published in Professional Boatbuilder.* Briefly, charge accumulates on all conductors on the boat,* even when current is flowing into the water.* The charge density is largest close to the water and on sharp corners and edges of conductors, which is thus where sparks are most likely to start.* So sharp corners are highly desirable on the outside of grounding plates and are recommended in most standards.* As well as initiating current flow, spark formation reduces the grounding resistance, thereby lowering the voltage of the whole protection system.* There is experimental evidence that the eventual effective area of the sparks formed from at the water surface above-water fittings may be hundreds or thousands of square feet.* See a brief discussion of this mechanism below.
In summary, the major problem with charge dissipation into the water is how to provide the appropriate number and distribution of grounding conductors, to eliminate sideflashes,* while minimizing the corrosive effects of multiple immersed conductors that are bonded together.
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Old 17-10-2016, 06:38   #15
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Re: Lightning Strike! Whats the likely damage and preventive measures.

Excellent presentation. I've got a broom shaped dissipator at the mast head, but as most have said there is no real prediction on what lightning will do. Disconnect shore power, turn the battery off..hope for the best.
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