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Old 29-07-2008, 10:30   #31
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For those with Strikeshield, can anyone advise what the manufacturer recommends for the depth below the surface of the anode when deployed? Do they advise of any reduction in efficiency if/when the anode tends to rise while underway?

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Old 29-07-2008, 11:57   #32
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Rob, I don't think I am allowed to post a direct link into another forum (I recall some kind of feather ruffling about this a while back), but it is the CSBB forum. The person who's boat was hit has posted here in the past, but I haven't seen him here in a while.

Brad, the manufacturer recommends 3-5 feet below the surface. They don't mention anything about reduction in efficiency underway, and my experience is that it is not 3-5 feet below the surface while underway (more like 1'). However, it seems the purpose is to direct the strike to the seawater, so as long as contact is maintained it should still fulfill its function.

Mark
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Old 29-07-2008, 12:08   #33
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Strikeshield would better than nothing. I doubt there is a perfect solution when it comes to lightning protection. Lightning sort of has a mind of its own in that we cant control it, we can only encourage it. At least it's not like the weather with which we have no control over.
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Old 29-07-2008, 15:23   #34
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As I mentioned earlier, the Strikeshield does nothing to protect you from lightning. Its only purpose is to provide a straight highly conductive path directly from your mast to the water with the hope that this will minimize the chances of lightning taking a more destructive path through the boat.

It is of most use to multihulls because these boats generally are difficult to establish a lightning bonding system in (mast sits over the water between the hulls and don't have large lead or iron keels to bond to).

Mark
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Old 30-07-2008, 08:52   #35
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Thanks Mark, my concern was whether there would be a greater tendancy towards a discharge back towards the hull if the anode was closer to the surface (some are stuggesting that this is a real problem).

Regardless, I'm still playing with the idea of not only a system like the Strikeshield but also heavy copper cable temporarily attached to the stays/shrouds and ending in anodes below the surface. The latter technique is one I had used for years in a series of monohulls and can say that several years ago, a nearby boat under anchor in Georgian Bay (with a much shorter mast) received a strike resulting in pinholes at the waterline while mine went unscathed. I know, I know, it could have been coincidence, but I was on anchor watch when the boat was struck and saw the sparks of current going down the shrouds on the boat that was struck. The mast is clearly the most direct path and is therefore the first thing that requires grounding, but...

Brad
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Old 30-07-2008, 14:59   #36
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Originally Posted by Southern Star View Post
Thanks Mark, my concern was whether there would be a greater tendancy towards a discharge back towards the hull if the anode was closer to the surface (some are stuggesting that this is a real problem).

Regardless, I'm still playing with the idea of not only a system like the Strikeshield but also heavy copper cable temporarily attached to the stays/shrouds and ending in anodes below the surface. The latter technique is one I had used for years in a series of monohulls and can say that several years ago, a nearby boat under anchor in Georgian Bay (with a much shorter mast) received a strike resulting in pinholes at the waterline while mine went unscathed. I know, I know, it could have been coincidence, but I was on anchor watch when the boat was struck and saw the sparks of current going down the shrouds on the boat that was struck. The mast is clearly the most direct path and is therefore the first thing that requires grounding, but...

Brad
Hi Brad,

Good point on the back discharge. I don't know, but it seems that the water would dissipate the energy quickly and there is no electrical attraction from the water to the hulls. If there was some physical reason for a strike to discharge from the water to the hulls, I don't think the difference from having the anode 1' below vs 3' below would be significant.

Your idea of also bonding the shrouds can't hurt. On the surface it seems like a good idea to provide as many controlled paths to the water as possible.

I spent a lot of time sailing Georgian Bay and the North Channel. Maybe some of the best cruising grounds in the world. At least they were back in the 80's - seems like every place is full of stripmalls, Walmarts and Home Depots now. Wouldn't surprise me if Bear Drop is now a shopping mall and Lion's Head a mega-marine center.

Mark
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Old 30-07-2008, 15:09   #37
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Quote:
Originally Posted by Southern Star View Post
... several years ago, a nearby boat under anchor in Georgian Bay (with a much shorter mast) received a strike resulting in pinholes at the waterline while mine went unscathed. I know, I know, it could have been coincidence, but I was on anchor watch when the boat was struck and saw the sparks of current going down the shrouds on the boat that was struck. The mast is clearly the most direct path and is therefore the first thing that requires grounding, but...Brad


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Originally Posted by colemj View Post
As I mentioned earlier, the Strikeshield does nothing to protect you from lightning. Its only purpose is to provide a straight highly conductive path directly from your mast to the water with the hope that this will minimize the chances of lightning taking a more destructive path through the boat...Mark

BRAD: See Mark’s contribution. Grounding/Bonding does nothing to prevent a lightning strike – it only reduces the damage, if/when one occurs.
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Old 30-07-2008, 16:38   #38
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All of this detail and projection is giving me a headache. I have a trimaran (Searunner 40) with the mast stepping astride the centerboard trunk, essentially a big hole in the boat leading straight down, three feet, to the ocean. The mast is supported by a 1/2" stainless steel "bridge". If I flatten a 3/4" copper pipe, drill a hole at one end, securing it to the mast step, and secure the other end to a 1/4" copper shoe at the base of the minikeel ( a 1 foot projecting mass of lumber, plywood and epoxy/fiberglass surrounding the centerboard trunk), that gives me a straight, heavy duty conductor, six feet from mast to shoe. Still, the thought of all that current blasting down is terrifying. That's why I haven't done it (yet).
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Old 30-07-2008, 19:42   #39
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Still, the thought of all that current blasting down is terrifying. That's why I haven't done it (yet).
But think about all that curret blasting down without a conductor there - because that is most likely the path it would take - it could do much much more damage.
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Old 30-07-2008, 19:49   #40
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Rob, I don't think I am allowed to post a direct link into another forum (I recall some kind of feather ruffling about this a while back), but it is the CSBB forum. The person who's boat was hit has posted here in the past, but I haven't seen him here in a while.

Brad, the manufacturer recommends 3-5 feet below the surface. They don't mention anything about reduction in efficiency underway, and my experience is that it is not 3-5 feet below the surface while underway (more like 1'). However, it seems the purpose is to direct the strike to the seawater, so as long as contact is maintained it should still fulfill its function.

Mark
G'day,

Thanks Mark. Interesting stuff and some examples of carbon masts unaffected by lightning, including this quote from a rigger in "the lightning capital of the world"
start quote
the only damage I've ever seen is at the occasional strike point or exit point. There are a load of variables involved (too many to get going on about here) from construction to condition of the carbon mast.
Although carbon has conductive properties, most of the time I see that lightning hits antennas, AWI's and standing rigging then travels down the path of least resistance leaving the mast alone. end quote.



The conclusion of the thread is that the stories about carbon masts exploding in lightning strikes, and/or melting into puddles of epoxy and carbon are urban myths, probably started by people with over active imaginations, or trying to sell aluminium.


regards,

Rob
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Old 30-07-2008, 21:12   #41
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Rob,

I shared my personal experience about my catamaran being struck by lightning recently and informed the group about the catamaran near mine taking the direct hit which destroyed (set on fire) his $100,000 carbon fibre mast and blowing a large hole in the bridge deck. (post 14) There was no melting puddles of epoxy and carbon and the incident was no urban myth, in fact it is costing $35,00 to repair my own boat. And just for the record Rob, I do not sell aluminium masts !!

Many people have their own opinions when it comes to lightning and lightning protection and it always makes an interesting topic for discussion on this site, but the astute reader should follow up all claims and information with the latest scientific facts and not try and summarize his informed conclusions and present it as facts just because some rigger in "the lightning capital of the world" (could be many places I have been) told him so !!

The correct conclusion to this thread should read.........

Catamarans are more prone to lightning strikes than mono hulls
No lightning prevention will stop your boat from being struck by lightning, and if you are lucky it MAY minimise the damage sustained.
Carbon masts DO get struck by lightning AND can catch fire
There is NO lightning capital of the world, just some places are more prone to electrical storms than others
Whether to install lightning protection or not is a personal decision based on chance, cost, difficulty, aesthetic, etc
If you have nothing to benefit this site then you should stick to reading as you might learn some thing.

Rob,

As you live in Perth you may consider a trip down to Hillary's boat yard and ask to have a look at the catamaran called "Claudette" and then come back to the group and inform every body on your findings of the urban myth about carbon fibre masts being immune to lightning strikes.

I look forward to reading about your findings...........
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Old 30-07-2008, 22:25   #42
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Rob,

I shared my personal experience about my catamaran being struck by lightning recently and informed the group about the catamaran near mine taking the direct hit which destroyed (set on fire) his $100,000 carbon fibre mast and blowing a large hole in the bridge deck. (post 14) There was no melting puddles of epoxy and carbon and the incident was no urban myth, in fact it is costing $35,00 to repair my own boat. And just for the record Rob, I do not sell aluminium masts !!

Many people have their own opinions when it comes to lightning and lightning protection and it always makes an interesting topic for discussion on this site, but the astute reader should follow up all claims and information with the latest scientific facts and not try and summarize his informed conclusions and present it as facts just because some rigger in "the lightning capital of the world" (could be many places I have been) told him so !!

The correct conclusion to this thread should read.........

Catamarans are more prone to lightning strikes than mono hulls
No lightning prevention will stop your boat from being struck by lightning, and if you are lucky it MAY minimise the damage sustained.
Carbon masts DO get struck by lightning AND can catch fire
There is NO lightning capital of the world, just some places are more prone to electrical storms than others
Whether to install lightning protection or not is a personal decision based on chance, cost, difficulty, aesthetic, etc
If you have nothing to benefit this site then you should stick to reading as you might learn some thing.

Rob,

As you live in Perth you may consider a trip down to Hillary's boat yard and ask to have a look at the catamaran called "Claudette" and then come back to the group and inform every body on your findings of the urban myth about carbon fibre masts being immune to lightning strikes.

I look forward to reading about your findings...........
G'day,

The conclusion referred to the other thread (which we are not allowed to mention on this forum). The alloy mast salesman comment was mine and was a dig at someone from another forum. Sorry it upset you. It was not aimed at you.

My post was not trying to minimise what happened to your boat and the one next door, or implying that your story was anything other than horrific. I do sell carbon masts and want to know all there is to know about them and lightning.

I will go up to Hilary's tomorrow and have a look. Could you email (harryproa@gmail.com) or ph me (92843483) with the owners name, email or phone number please?

I would like to find out as much as I can about the mast construction and what burnt and why. Happy to report back if I find out anything of interest.

regards,

Rob
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Old 31-07-2008, 00:57   #43
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G'day,

Crak,

Just got back from Hilary's. Not sure what your agenda is, but I hope you were less dramatic with your insurance claim than your were with this forum.

My findings, as you requested.

The boat is a Schionning Waterline, named Clawdette, (not Claudette) never been sailed by the owner, recently arrived up here. The lightning strike appeared to enter the top of the mast and the forestay. There is a small amount of damage (couple of inches square) just under the mast head (looks like 4 or 5 layers of laminate have been damaged, hard to tell without a grinder). This is almost cosmetic and could be fixed in an afternoon. There is a similar sized area of damage a little further down the mast, not sure what this was caused by. As it is in a stressed area, repair would take a little longer. There is a bit of damage to the carbon laminate under the mast base. Another couple of hours work. NO other visible damage. The mast is pristine, shiny white paint, there is no evidence of fire or smoke damage, nor of any paint blistering, so I suspect it did not even get hot, much less ignite. I have seen more damage to carbon masts where fittings held on with self tapping screws have been torn out.

I spoke to the yard manager (turns out we have some mutual friends from the last English America's Cup challenge, which we were both involved with) who showed me the mast and the underside of the boat. He said he had been involved in the assessment of the damage and that the insurance company were reluctantly writing it off as there is no ultrasound testing equipment in this part of the world. It was pouring with rain so I did not go on deck. According to the manager, there was NO damage on deck at all.

There is a small area of delamination under the anchor winch, which is where they assume the lightning went to earth. This is a flat area and easily repaired.

So, probably no hole (large or small) in the deck, definitely no fire involving the mast, and definitely no "destroyed" mast. Another attempt to start an urban myth laid to rest.

I am waiting for the assessor to ring me back so I can make an offer on the mast, which subject to the repairs and some static tests could be back on a boat the week after next. I will also be offering to build a new one for the owner. This one may have cost over $100,000, but we can replace it for less than half that.

The yard manager invited me back next week to show me the lack of damage to the deck. Happy to meet you up there then so you can see what really happened.

I doubt I will get it, but I think you owe me, and the rest of the list an apology. You may also want to have another look at your conclusions and edit or remove your posts.

regards,

Rob
Quote:
Originally Posted by Crak View Post
Rob,

I shared my personal experience about my catamaran being struck by lightning recently and informed the group about the catamaran near mine taking the direct hit which destroyed (set on fire) his $100,000 carbon fibre mast and blowing a large hole in the bridge deck. (post 14) There was no melting puddles of epoxy and carbon and the incident was no urban myth, in fact it is costing $35,00 to repair my own boat. And just for the record Rob, I do not sell aluminium masts !!

Many people have their own opinions when it comes to lightning and lightning protection and it always makes an interesting topic for discussion on this site, but the astute reader should follow up all claims and information with the latest scientific facts and not try and summarize his informed conclusions and present it as facts just because some rigger in "the lightning capital of the world" (could be many places I have been) told him so !!

The correct conclusion to this thread should read.........

Catamarans are more prone to lightning strikes than mono hulls
No lightning prevention will stop your boat from being struck by lightning, and if you are lucky it MAY minimise the damage sustained.
Carbon masts DO get struck by lightning AND can catch fire
There is NO lightning capital of the world, just some places are more prone to electrical storms than others
Whether to install lightning protection or not is a personal decision based on chance, cost, difficulty, aesthetic, etc
If you have nothing to benefit this site then you should stick to reading as you might learn some thing.

Rob,

As you live in Perth you may consider a trip down to Hillary's boat yard and ask to have a look at the catamaran called "Claudette" and then come back to the group and inform every body on your findings of the urban myth about carbon fibre masts being immune to lightning strikes.

I look forward to reading about your findings...........
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Old 31-07-2008, 08:39   #44
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G'day,

Crak,

Just got back from Hilary's.

Rob
Thanks for looking at the cat for us Rob!!



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Old 31-07-2008, 10:22   #45
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Gord, you are of course correct about no grounding system preventing a strike, but the boat that was struck directly was so close that I received a few sparks on my rigging, an immediate smell of ozone and yet received no damage. Yes, it may be that I would not have anyway (as I said); nevertheless, I still suspect that I would have received some damage secondary to his strike had mine not been grounded in any way (and apart from the grounding of the shrouds/stays, the mast itself was grounded to the cast iron keel).

I am wondering if there is any rational behind the suggestion that cats are more susceptible than monos to lightening strikes?

Brad
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