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Old 26-09-2009, 09:28   #46
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Originally Posted by Reality Check View Post
One poster asked about attaching a copper wire to the chainplates and running it into the water... Probably not a good idea.
[...]
Faraday Shield
[...]
Some feel the standard metal rigging on a sail boat would provide a somewhat effective Faraday Shield but it is far from ideal... or even good.
Reality,

All the research that I read states that the Faraday cage created by mast and rigging is pretty effective. In fact, I have never read any report that it didn't work (I don't mean that it creates a perfect Faraday cage in theory). So, why do you imply the opposite, can you provide some citations that support your pov? Is your rigging bonded?

Also, even if one believes that it's so-so, wouldn't that still be better than nothing. What is the reason you discourage others to bond their rigging? I am an electric engineer too, so don't worry to use tech-terms.

ciao!
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Old 27-09-2009, 15:55   #47
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But what we can do on a boat is just the 'normal' stuff of turning off the electricty, unplugging the computer (etc) and putting the handheld GPS away from the Nav switch pannel etc.
The portable electronic items (i.e. cell phones, handheld GPS, etc) can be popped into the cold oven which acts like a Faraday cage. It's not perfect, and don't forget them in there, but it's better than nothing.
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Old 27-09-2009, 16:12   #48
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Any comments/opinions on Strikeshield?
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Old 27-09-2009, 16:30   #49
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Any comments/opinions on Strikeshield?
We only have second hand anecdotal results. Our Maine Cat 41 comes with the StrikeShield as standard equipment. We also haven't had a lightning strike yet. Our builder explained it this way (not a direct quote):

I was getting a lot of calls from our Maine Cat 30 owners in Florida who were being struck by lightning and did some investigating. The StrikeShield looked to be the best product on the market, so I offered it to them and made it part of the standard package on our boats. Since then, I have not received one call about a lightning strike.

Fair Winds,
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Old 27-09-2009, 16:58   #50
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Thanks Mike.
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Old 28-09-2009, 06:11   #51
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Quote:
Originally Posted by mikeandrebecca View Post
Any comments/opinions on Strikeshield?
Mike,
I used the Strikeshield for 7 years on my Manta 42 with great success. I have had it on my St Francis now for 2 years (knock on wood). I have two commercial type bottle brushes on the mast from IPS Marine 401-846-3724. Great system while stationary, in theory the brushes are not doing anything for you unless the strikeshield is in the water. I did rig guy lines to my bow prod eyes down near the water line so I could deploy it during lighting while underway without it bashing holes in the bridge deck. Never did deploy it while underway though.
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Old 28-09-2009, 06:20   #52
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Again, FWIW, YMMV, blah, blah, blah...

We have deployed the StrikeShield while underway in seas up to 10'/3m without problem. I was certain that the heavy metal end was bashing holes in the boat when we were bashing to windward in a storm, but watching it through one of the escape hatches proved me totally wrong (that's NEVER happened B4!) - never came close!

Fair Winds,
Mike
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Old 01-10-2009, 14:23   #53
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If I would sail a cat, my worry would not be the statistical chance of being hit more often than a mono hull.... my worry would be about what would happen to me and the boat when lightning strikes. For some reason, only few in this thread share that point of view.
Well, nothing happens. You pick the bits and pieces out your hair, brush yourself off and head to the marina. Then begin the process of writing checks to cover the damage.

I have been struck while underway. Yes I have a catamaran. No, there was no hull or engine damage. Yes, I lost everything connected into 12VDC.

My experience was featured in the June 2009 issue of Southwinds magazine and there is an account of it here:

Repairing Lightning Damage on My Boat
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Old 01-10-2009, 15:05   #54
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Well, nothing happens. You pick the bits and pieces out your hair, brush yourself off and head to the marina. Then begin the process of writing checks to cover the damage.
You were lucky. There are many reported incidents where the strike left punctures through the hull laminate or vaporized thru hull fittings etc. Or where arcing hit crew members.

cheers,
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Old 01-10-2009, 15:19   #55
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Catamarans

"According to Boat US insurance claims, they are struck twice as frequently as monohulls of similar length."

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The following statistics are based on all of the BoatUS Marine Insurance claims for lightning damage over a five-year period. The percentages suggest the chances of the various types of boats being struck in any given year (not over a lifetime)
Auxiliary Sail 0.006 (0.6%) Sixty out of 10,000
Multi-hull sail 0.005 (0.5%) Fifty out of 10,000
Trawlers 0.003 (0.3%) Thirty out of 10,000
Sail Only 0.002 (0.2%) Twenty out of 10,000
Cruisers 0.001 (0.1%) Ten out of 10,000
Runabouts 0.0002 (0.02%) Two out of 10,000

Hmmmmmm.........maybe somebody with something to sell isn't telling the truth?
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Old 03-10-2009, 05:49   #56
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You were lucky. There are many reported incidents where the strike left punctures through the hull laminate or vaporized thru hull fittings etc. Or where arcing hit crew members.

cheers,
Nick.
Well, speaking for myself, I could do without this kind of 'luck'. It was a very expensive experience. I sail in lightning quite a bit, although never on purpose, and have a fair amount of experience as I live in what's called the lightning capital of the world. The key to lightning management seems to be staying out of shallow waters during a storm. This is a non issue for monohulls and I notice no one has mentioned it in this thread as a reason cats might be more susceptible to lightning strikes. We spend more time in very shallow water, because we can.

As an aside, I have no bonding or lightning protection of any kind on my cat. It just isn't necessary. The Mast and Stays provide a cone of protection for crew and if thru hulls are replaced with Marlon and the boat has an inboard engine, (or two as in our case) people's experience should be similar to ours. Electronics will be lost, of course.

Boat's with outboard engines have issues with hull damage after strikes as the electricity obviously takes the easiest path to ground. This is where hull damage occurs.

I've never heard of a sailor being electrocuted by a lightning hit and would love for you to point me to that story you mentioned.
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Old 03-10-2009, 06:09   #57
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... I have no bonding or lightning protection of any kind on my cat. It just isn't necessary. The Mast and Stays provide a cone of protection for crew and if thru hulls are replaced with Marlon and the boat has an inboard engine, (or two as in our case) people's experience should be similar to ours. Electronics will be lost, of course...
Any electrically conductive object, grounded or not, can attract lightning.

Lightning leaves an ungrounded object (to one that is, like the water) by converting enormous energy into heat. Once embarked on a continuously bonded and low-impedance path to ground, lightning ceases to convert as much energy into heat, and dissipates into earth in a much less destructive manner. The less conductive the grounding path (from attachment to water), the more damage usually results where lightning leaves the boat. To lightning, virtually everything is somewhat conductive.
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Old 04-10-2009, 14:56   #58
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This is a timely topic for me as I just finished replacing all the electronics on my catamaran (The Ligthning Strike). I had a wire dropped down from the mast support and scorch marks showed that most of the charge went through the mast support. Burn marks on the breaker panel showed that the anchor light and spreader light conducted current into the breaker panel and probably from there to everything else. The outboards were fried even thought they were lifted clear of the water.
I am adding fuses and transient suppressers to the mast wiring and disconnects for all the electronics and the engines. Does anyone else have plans or thoughts on hardening their boat?
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Old 04-10-2009, 15:09   #59
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I am adding fuses and transient suppressers to the mast wiring and disconnects for all the electronics and the engines. Does anyone else have plans or thoughts on hardening their boat?
As for protection? It sounds as though you didn't suffer hull / boat damage either. I'm certain you're electronics suffered the same fate as mine.

Repairing Lightning Damage on My Boat

I wouldn't know where to locate a transient suppressor which could handle a direct lightning hit, and if I could, I can't imagine it would fit on my boat. I can't think of anything else that would protect electronics other than disconnecting them from 12VDC. As you can see from that link I posted, all electronic devices operating on internal batteries... ie: cell phones, gps, camera, were completely unaffected by the lightning hit on my boat, while anything connected to 12VDC was blown to smithereens.
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Old 04-10-2009, 19:04   #60
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I am not trying to suppress the lightning strike, just the part going to the electronics. Everyting on the top of the mast was totally destroyed but the breaker panel had only minor damage. The scorch marks indicate that most of the current went through the mast step and into the grounding wire. My theory is that the portion going down the mast wiring will blow out a fuse and the suppressor STM Microelectronics 1.5KE18A will keep the voltage down until the fuse blows. I will let you know how it works after the next strike.
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