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  #1  
Old 02-06-2007
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Lightning Ground

I've narrowed my search down to two boats: a used, late-model Valiant 42 and a new Caliber 40 (both around the same price and similarly equipped).

The Valiant treats the issue of potential lightning strikes as follows:

"Very extensive grounding of mast, stanchions, thru-hull fittings, etc."

The Caliber does the following:

Nothing. The dealer claims that Caliber says, "it's unnecessary."

I expect to cruise in areas where lightning is common at certain times of the year.

How big of a consideration should this be in making my decision? My understanding of the conventional wisdom on the subject is that, with the grounding you increase the likelihood of actually getting struck, but minimize potential structural damage. However, if you don't have the grounding and are struck, the damage can be much more severe.

Could you experienced cruisers please give me your opinions?

Thanks,

Fritz
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Old 02-06-2007
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Again... a quick look at other lightning threads would have told you quite a bit... but since you don't seem able to do that...

A boat with a proper lightning bonding and grounding system will have more of a chance of getting hit, but will generally suffer less damage than a boat that is ungrounded/unbonded in the case of a lightning strike. Conversely, an unbonded/ungrounded boat will generally get hit less often but has a greater chance of having catastrophic damage done if it should get hit.

The tradeoff is whether you rather be hit and protected better or risk getting hit harder but more rarely. In either case, lightning strikes are fairly rare.

Also, a good site to check out is Dr. Thomson's site. This site is probably referred to at least once in any thread discussing marine lightning protection systems.

From what I've seen, most boats do not have a lightning bonding/grounding system in place.

A badly designed lightning protection system can increase your risk of sinking. You should never ground thru-hull fittings to a lightning protection system, and if Valiant is doing so, they're being pretty stupid about it. Lightning will never strike at a thru-hull, which is below the water's surface, and there isn't really enough metal there to make bonding it worthwhile. Thruhulls should be bonded in a galvanic corrosion protection system, but not in a lightning protection system. The only parts that should be bonded are the major, above waterline components, and they should be connected to a grounding strip embedded in the exterior part of the hull. The stays, shrouds, and mast, and possibly the pulpit, pushpit and lifelines should be connected with heavy #4 AWG wire. The mast should be connected to the grounding strip with a heavy #4 AWG wire, running as close to vertical with as few bends in it as possible.

The thru-hulls, engine and electrical system should be isolated from the lightning bonding system... as should any galvanic prevention system.
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Old 02-06-2007
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Dr. Thomson's video:

www.thomson.ece.ufl.edu/lightning/sailboats.ram
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Old 02-06-2007
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Quote:
Originally Posted by sailingdog
Thruhulls should be bonded in a galvanic corrosion protection system, but not in a lightning protection system.
I always wondered about that. Is it truly necessary to do galvanic isolation for bronze thruhulls? I thought that since bronze has very low anodic index it really isn't very succeptible to that, unless of course other parts are made of gold or something.

Besides, according to articles on galvanic corrosion, in order for it to happen there must be an electric connection between the anodes-to-be, and so bonding system between thruhulls and engine might provide just that? Wouldn't that make things worse?

Last edited by brak; 02-06-2007 at 08:53 PM.
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Old 02-06-2007
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ABYC Standards

Quote:
Originally Posted by FritzN
I've narrowed my search down to two boats: a used, late-model Valiant 42 and a new Caliber 40 (both around the same price and similarly equipped).

The Valiant treats the issue of potential lightning strikes as follows:

"Very extensive grounding of mast, stanchions, thru-hull fittings, etc."

The Caliber does the following:

Nothing. The dealer claims that Caliber says, "it's unnecessary."......Could you experienced cruisers please give me your opinions?
Yikes, here's yesterday's thread on lightning Lightning protection on 1991 Hunter 30 which references last week's which...Most of this message will be in that thread...

It sounds like Valiant builds their boats to meet the ABYC standards for ligthning protection ( See Section E-4 http://www.abycinc.org/standards/purpose.cfm#E4 . A good yard or builder would likely have a copy of the full ABYC specs.)

I expect the Caliber has a grounded mast, but no more. Given a choice, I'd rather have a boat meeting the ABYC specs. However, I would not PAY to meet the ABYC specs (as I told my insurance company following last year's survey raising that issue. The cost of retrofiting a 36 footer with a full bonding system was in the area $4,000, I did not think it wortht it, and apparently the insurance company concurs or at least choses not to debate it).

I agree with SD that full ligthening bonding bonding systems (per the ABYC) are not common. I'd guess this rarity is an example of features that seperate the Sabres and Tartans ($$-$$$) from the Catalinas and Beneteaus ($-$$), and apparently Valiants from Calibers (beats me, don't know either)...I would think that most boats do have grounded masts for basic lightning protection. Whether grounding increases the risk of a hit or not, such grounding serves to protect crew and the hull from the worst of a strike.

PS: Camaraderie, how about speaking with the powers-that-be in Sailnet about starting a FAQs page to capture the gist of threads like these which re-occur so often...

Last edited by sailingfool; 02-06-2007 at 09:09 PM.
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Old 02-06-2007
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I was just considering installation of grounding plates last week when my boat was on the hard. However, after the reading, consultation with yards in NW, thickness of my pocket book, I chose to wait. During my years of installing electronics on 300 -500 ft. towers. Rule #1 don't put anything on top. R #2 isolate it, R #3 -Upon seeing the flash, pray and take another drink
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Old 02-06-2007
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SF... Camaraderie, how about speaking with the powers-that-be in Sailnet about starting a FAQs page to capture the gist of threads like these which re-occur so often...

That would be kinda counter productive to active discussion which is how sites like this make $$. Also while there's lots of opinion here...FAQ's kinda imply that "here are the answers"...and it seems about the only thing everyone agrees on is the "Miracle Cloth"!!
On the other hand...you might just wanna keep an archive of your own best posts so you can just cut and paste...both of them!!!
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Old 02-07-2007
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—Cpt. Mal Reynolds, Serenity (edited)

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  #9  
Old 02-07-2007
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If I was cruising the Pacific NW, no way I would spend a dollar on grounding systems. Why? How many days/year do you have major electrical storms?

On the other hand, if I was hitting the south florida, Bahamas, and surrounding islands on down south, I sure would consider it. We have, on average, about 100+ days/year of serious lightning storms.

http://www.cdc.gov/nasd/docs/d000001...7/d000007.html

In the summer, spring a bit, and fall, about every day at 2:00 you get a very strong storm. They may not last very long, but it is strike, after strike, after strike (all around you). That is about 1 out of every three days. Now, you make your own decisions from there...

I did not ground my 380 down there. I did not get hit. But I AM going to ground my 400, extensively. I will follow ABYC. Here is a nice write-up.

http://www.kastenmarine.com/Lightning.htm

If I was going offshore much, I would ground, period. A strike offshore could be devasting without a clear path to ground.

Bottom line, I think you need to outline where you are going to cruise, then decide from there what measures you need to take to assure your safety and that of your crew.

- CD

PS If I was deciding between a Valiant and a Caliber, there would not be a decision. Valiant every time, twice on sunday. Nothing wrong with a Caliber, nice boat, but it is NOOO Valiant in my opinion. It is a bit more roomy though and typically less expensive. You might probe the other members of this forum on that question in boat buying.
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Old 02-08-2007
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Well...it's either the shroud of Turin or some metal polish thingamagiggy that west marine sells for exorbitant prices.
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