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Old 19-09-2014, 21:10   #1
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Lightning Strikes and Cats

I am currently in the market for a 45-55 foot catamaran for full time cruising. I have it narrowed down to just a couple different brands of boats so don't need help with that. My question is that one of the boats I have in mind has been struck by lightning not once but twice. The owner says everything checked out fine per a survey except the electronics. All of those have been replaced with new. Should I even consider this boat and if I do is there a way to ensure that everything is in order via a through survey? I live on the left coast so not much experience with lightning strikes and it's aftermath on boat strikes. I am very interested in this particular boat as there aren't many like it but I don't want to get stuck with something that has a billion holes in it that I can't see.


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Old 19-09-2014, 21:56   #2
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Re: Lightning strikes and cats

A friend's Lagoon was affected by lightning. What didn't burn ended up breaking even months after. Incandescent filaments, gps right away, radar, charger later on. Many other things got damaged but no sign of direct hit.

My take from it is that electronics may seem fine but won't be trust worthy later on.
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Old 19-09-2014, 23:31   #3
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Re: Lightning strikes and cats

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Originally Posted by fcftampa View Post
A friend's Lagoon was affected by lightning. What didn't burn ended up breaking even months after. Incandescent filaments, gps right away, radar, charger later on. Many other things got damaged but no sign of direct hit.

My take from it is that electronics may seem fine but won't be trust worthy later on.
+1. I've seen electrical gremlins persist long after a strike and repairs.

I would not rule out a boat because of a strike, but something to be aware of.
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Old 19-09-2014, 23:36   #4
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Re: Lightning strikes and cats

Aside from all things electrical, you might want to check the integrity of all through hulls in case the strike grounded through one or more of them.
Last I read, multihulls are 50% more likely to be hit by lightning and suffer 70% more damage when hit than other types of craft. That's why I am going to build in a lightning mitigation/protection system on our new cat.


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Old 20-09-2014, 00:31   #5
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Re: Lightning strikes and cats

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Last I read, multihulls are 50% more likely to be hit by lightning and suffer 70% more damage when hit than other types of craft. That's why I am going to build in a lightning mitigation/protection system on our new cat.
Reference?, I mean that genuinely and respectfully. We had Professor Darveniza from UQ at the MYCQ meeting a few years back to talk about lightning, and his only observation was that a bigger boat was slightly more likely than a small boat to be hit (and even that was in the order of tenths of a percent), and that amount of boat in the air (mast) and in the water(Wetted surface) were possible concerns, if I remember correctly. Professor Darveniza is a world renowned expert on lightning.
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Old 20-09-2014, 02:21   #6
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Re: Lightning strikes and cats

Hi Factor,

Reference is from Ewen Thomson's site on lightning protection,

About MLP

Data was collected in US over 10 years on hits on boats in marinas comparing boat types, type and amount of damage & boat position relative to the "mast herd" effect. Cats were most hit even with other masted boats around them but when they were on slip positions away from other masted boats, like at end of T slipways, they were at even greater risk & most damage. More anecdotal evidence suggests if anchored out, the risk goes up again.

I'd be interested to see the data that forms the basis of Prof. Darveniza's viewpoint. Did he indicate how they came to that conclusion because it seems at odds (perhaps) to the US study.
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Old 20-09-2014, 02:48   #7
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Re: Lightning strikes and cats

This is the link to the page concerning strikes on catamarans.
Catamarans
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Old 20-09-2014, 02:55   #8
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Re: Lightning strikes and cats

I have a cabinet maker friend who specialises in restoring antique houses and old furniture.

He has an interesting technique. Using car batteries, he puts the positive and negative across an area he wants to strip of old paint and varnish and then leaves it until the old stuff comes off. He uses very low voltage and time. It didnt damage the wood at all.

I saw him once zap an area with 24 volts. The results were startling.. the paint became brittle a few days after removing the charge.

I have no idea what a full lightening strike would do long term...... I have a gut feeling that it is doing something. Guess it depends on the materials etc.

Just a passing comment.
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Old 20-09-2014, 03:36   #9
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Re: Lightning strikes and cats

I don't have a reference it was just from a presentation by Mat Darevniza. All interesting stuff. It appears the Ewen Thompson has a similar background to Darveniza as well. I wonder why the US data indicates that cats are most hit, as in what the underlying physics is. Seawind does offer a Lightening Protection System as an option on new boats and I have been interested in understanding, in so far as I can, what LP systems do and how.
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Old 20-09-2014, 04:45   #10
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Re: Lightning strikes and cats

The answers to your questions are on that website. Is there a document from Seawind that outlines their approach? Had a quick look on the Seawind website and didn't see it referred to.
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Old 20-09-2014, 05:13   #11
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Re: Lightning strikes and cats

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Originally Posted by Factor View Post
I wonder why the US data indicates that cats are most hit, as in what the underlying physics is. Seawind does offer a Lightening Protection System as an option on new boats and I have been interested in understanding, in so far as I can, what LP systems do and how.
Really good point, Factor, I do believe.
We had quite a lot of discussions regarding effects of lightning strikes. On the other hand I can not recall any really systematic thread regarding the available solutions for lightning protection systems, their effectveness, pros and cons and so on.
Just a rough idea - as You are obviously interested in some digging into this matter, why not to start and take some care about such a thread?
It can be very useful to exchange and analyse all possible, up to date options, I assume

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Old 20-09-2014, 05:56   #12
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Re: Lightning strikes and cats

A few years ago on this forum in a similar thread an insurance company actuary (statistical mathematician) went and checked all claims and could find no difference in boat type, number of masts and if there was ligtning protection.

He said if there was some difference there would be differences in insurance rates for certain type boats.

I prefer to beive him than a company trying to sell you lightning protection.

Of course, i cant find the thread....
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Old 20-09-2014, 06:30   #13
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Re: Lightning Strikes and Cats

The data was gathered over a decade period by US Yachting body, so if there is better data, I'm sure we'd like to see it. It's the best data I've been able to find so far, and it is quite unrelated to whether someone is offering a service to help sailors protect their boats using their expertise.




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Old 20-09-2014, 07:05   #14
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Re: Lightning Strikes and Cats

Your Boat's Been Hit By Lightning - Now What? - Seaworthy - BoatUS

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One surprise: Multihull sailboats are struck more than twice as often as monohulls. Even accounting for the fact that a large percentage of multihulls are in lightning-prone Florida, the odds of multihulls being struck are still statistically much greater.
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Old 20-09-2014, 08:09   #15
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Re: Lightning Strikes and Cats

Last year in Panama the word was that only Cat got hit.

This year only ketch get hit and one was 200 ft from us and lot smaller.

In reality it's shear luck nothing else and perspective of the viewer for the story that follow.

On the inside is same thing no reason or logic in destruction Mother nature does what ever she wish.
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