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Old 08-07-2019, 08:22   #31
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Re: Lightning Protection, pros and cons

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0.5% to 1% seems high. Can you put up a link to this information?

I find it hard to believe that 1 out of every 200 boats gets hit by lightning every year.

If this were true, I'd imagine cruisers would be at significantly higher risk, than those at marinas. Being the only boat in an area, must increase the risk. Whereas those at marinas, especially the smaller boats, have the benefit of being within the cone of protection, of the larger boats.

We were hit, off bermuda, in 2006.
Minor electrical damage. Non-grounded mast.

The strike rate varies significantly with location, type of boat (sailboats are more at risk, catamarans especially so), size of boat (larger is worse). Unfortunately, most cruising boats are sailboats and also larger than the average coastal yacht, putting us in the high risk category. The other thing to consider is that the consequences of a severe strike are much more serious for a boat that is offshore.

I think your theory of boats cruising without other boats in close proximity having a greater risk is probably correct, but I have never seen any data. I did read a study that boats on the end of marina pontoons were significantly more at risk than those berthed somewhere in the middle, which sort of fits with the theory.

Here are a couple of articles discussing risk numbers:

The first is by Beth Leonard. The risk for all boats is only about 1 in 1000 per year (0.1%), but this jumps up to around 3.8 per thousand (0.38%) for sailboats in general and around 6 in a 1000 (0.6%) for larger sailboats:
https://wavetrain.net/2015/01/27/mar...on-a-sailboat/

The second is by Charles Doane:
https://wavetrain.net/2015/01/27/mar...on-a-sailboat/

This agrees reasonably closely with Beth’s numbers suggesting the risk for all boats is 1.2 per 1000 per year (0.12%) but for sailboats this jumps up up to 4 per 1000 (0.4%) but the article notes that these numbers underestimate this risk because of unreported strikes. They also note that some sources suggest with a 50 foot mast the risk is once every 11.4 years or 8.7% !!!! A rather frightening number especially for boats such as mine that have a taller mast than this.
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Old 08-07-2019, 08:27   #32
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Re: Lightning Protection, pros and cons

I was caught in a t-storm Friday coming in from the GOM to Pensacola Bay; lots of lightning and I saw a sailing cat at anchor get hit. Not fun for anyone.
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Old 08-07-2019, 08:38   #33
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Re: Lightning Protection, pros and cons

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Considering an aluminium mast is just standing there on a Fibreglass boat and is not connected to ground or earthed out in any way,
Why would it attract a lightning strike, ???????????
On anchor with a chain out, Yes then your earthed out,
Very small gap between your anchor chain and the front Guy wire for your mast,

Would it not be the same as an aircraft getting hit by lightning,
Its a large aluminium structure flying through the air and not earthed or grounded out,
They seem to be uneffected by lightning strikes,
Their electronics and wiring dont short out or melt when hit by lightning,

Its a totally different story if your mast is connected to the water in some way, Welding wires over the side into the water attached to the mast,
Then the mast is and will be grounded out,

I do not know of a boat with an electrical system that does not have some wiring connection from the mast to the water.
What about: VHF antennae wire and lights on mast wiring that goes to a distribution panel that is eventually grounded to the engine block and through the engine and shaft to the water?
I was sailing a catamaran about 200 miles offshore that was struck by lightning. There were grounding plates connected to a shroud both port and starboard, but the mast itself was not directly grounded. Lightning struct the mast top (there were marks on the mast top as if someone was trying to strike a welding arc) but did not travel down the shrouds, as the aluminum mast was a much better conductor for the massive charge. The charge travelled down the mast to the mast step and leaped the short gap between the mast step to the inverter and house battery bank just below it. The charge melted the inverter, burst the house battery bank, melted the distribution panel, ran down the ground wire to the engine to which the electrical system was grounded, burned out the starter and alternator and buckled the flywheel in the bellhousing and travelled out through the saildrive. Virtually every electrical item on the boat was burned out - lights, bilge pumps, instruments, radios (VHF and SSB), fridges, etc., but the integrity of the rig and the one remaining engine with its own starting battery was left in-tact.
On returning to my home port I installed a grounding plate and cable to the mast step on my own catamaran in addition to the grounding plates to the two shrouds.
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Old 08-07-2019, 09:43   #34
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Re: Lightning Protection, pros and cons

About 15 years back I had a Catalina 42 docked in Kemah marina in Houston. A lighting tower was hit and apparently it jumped to the masts as in a domino. I was docked about 30 boats away. Just like every boat in that dock lost electronics and #2 wire to the engine block was vaporized. Now on my Bene 52 I installed the dissipator of static electricity on top of the stick. I have been through some ugly tropical storms out in the Carib with no issues. The same boat with no dissipator in Curaçao 5 years ago got hit in Spanish waters marina. The anchoring light blew away along with vhf antenna became fg hair with the radio toasted with no other effect noted.
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Old 08-07-2019, 10:06   #35
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Re: Lightning Protection, pros and cons

Be thankful you don't sail in South Florida, the lightning capital of the United States! I'm with you! It scares me shirtless!
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Old 08-07-2019, 10:12   #36
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Re: Lightning Protection, pros and cons

I recall years ago reading an article on what it would take to totally protect the average sloop. What they came up with was many pointed rods below the water line all pointing in different directs, all bonded together.

I'm sorry I can't recall who did the study and experiments. If I find it in the cobwebs if my brain, I'll certainly post a link...to the article...not my brain..that's too scary.
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Old 08-07-2019, 10:18   #37
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Re: Lightning Protection, pros and cons

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I'd be interested in the literature on this statement, too. Especially the "spectacular fashion" part. Seems this is said a lot but can't find much evidence it is actually true.
A friend of mine is a professional rigger working mostly on high end yachts, and I trust his judgment. I picked his brains on the mast selection for our new boat. He was not against carbon fibre masts, but had lots of interesting stories concerning their vulnerability in the event of a lightning strike.

This makes sense. The aim is to conduct the strike to ground (the water) without generating excessive heat. The lower the resistance the less the damage. Hence the concept of using large copper conductors. Aluminium is a good conductor. Carbon fibre and epoxy less so. This, combined with low heat tolerance of epoxy, means carbon fibre is more vulnerable than aluminium. Most carbon fibre masts incorporate a large copper grounding wire to try and minimise this difference, but there are invariably areas of local heating with a lightning strike.

Interesting, there was also a comment that he occasionally receives requests from people that want components, and even their whole aluminium mast painted black to look like carbon fibre. However, it was not unusual for the wealthy to want their carbon fibre mast painted another colour, not just for aesthetics, but specifically so no one will realise it is carbon fibre. An interesting comment on human nature.

Clear coated carbon fibre is so beautiful I personally cannot imagine painting it as a disguise. Who cares what other people think.

BTW, I note you have a Freedom 38. Do you have an unstayed carbon mast? Have you seen the report on a Freedom 40 hit by lightning? It described how the lightning blew a hole in the mast showering the foredeck with splinters. It certainly sounded spectacular. One report does not mean much, and lightning can do anything, but aluminium masts do not normally behave like this. Aluminium masts do sometimes fall down following a lightning strike, but mostly from the fibreglass around the chainplates failing.

There was also a Freedom 40 lost offshore with all hands off Florida with speculation at the inquiry that the carbon fibre mast was destroyed by lightning, although considering the boat was totally lost it was not clear why this particular scenario was suggested.
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Old 08-07-2019, 10:55   #38
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Re: Lightning Protection, pros and cons

There are many many horror stories about lightning strikes on boats and how devastating a direct hit can be. It is true that holes can blow through the bottoms of boats both wood, steel and FRP. We are talking thousands of amps of energy that has to be dissipated instantly. Also true in the electrical world that electricity will take the easiest path to ground. - Usually!
I am no expert on lightning but would relay my own single experience with close strikes during a storm at sea. We were sailing for Moorea from Tahiti where we had been held up getting a visa extension. By the time we got away it was too late to see the reef entrance clearly and we decided to lie ahull off the entrance until morning light. A lighting storm blew up about midnight. I had a heavy (about 2/0 as I recall) 6' length of copper cable ready and clamped it to the upper shroud on my 36ft wood sailboat with about 1 foot of cover cut away. It was a true horror story. I sat in the cockpit and watched strike after strike hit the water very close to the boat for at least an hour or more. Difficult to tell how close because you suddenly go from darkness to blinding brilliance in a nanosecond. Thunder and lightning were together so very close. We were not struck, had no damage other than to our psyche and to this day I do not know if the cable over the side helped. However, next trip offshore I think I will have one ready.
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Old 08-07-2019, 11:01   #39
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Re: Lightning Protection, pros and cons

@Noelex 77

<<Clear coated carbon fibre is so beautiful I personally cannot imagine painting it as a disguise. Who cares what other people think.>>

One very good reason for painting a carbon fiber mast is it has very poor UV resistance. It is highly recommended to paint them for this reason.
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Old 08-07-2019, 11:09   #40
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Re: Lightning Protection, pros and cons

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I recall years ago reading an article on what it would take to totally protect the average sloop. What they came up with was many pointed rods below the water line all pointing in different directs, all bonded together.

I'm sorry I can't recall who did the study and experiments. If I find it in the cobwebs if my brain, I'll certainly post a link...to the article...not my brain..that's too scary.
Do you mean these guys?
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Old 08-07-2019, 11:15   #41
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Re: Lightning Protection, pros and cons

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Lightning does respect conductors all that much. Remember that it just hopped across a thousand feet or more of air which is generally considered pretty nonconductive. Concepts that make sense for 12 or 240 volts break down when the voltage is in the billion range. My boat has a grounding system as well as a lightning rod at the masthead, but I don't count on it to do much. The overpriced brush style dissipators are worthless. NASA says a rod with a 3/16" rounded tip is most effective and they have a bunch of really smart people protecting a lot of really expensive really tall toys in a really high risk area.
Pray tell - what does one do with this 3/16” rod you speak of? Where do I place it? What do I attach it to? Do I ground this rod? How do I ground it?

Is it a dissapator? A conductor?
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Old 08-07-2019, 12:22   #42
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Re: Lightning Protection, pros and cons

https://www.rt.com/usa/463624-boston...htning-strike/
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Old 08-07-2019, 12:33   #43
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Re: Lightning Protection, pros and cons

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One very good reason for painting a carbon fiber mast is it has very poor UV resistance. It is highly recommended to paint them for this reason.
Good point. It is important to apply a coating for UV protection, but there are clear coatings that have good UV blocking ability. UV by definition cannot be seen so a material that blocks UV can still appear transparent. Polycarbonate is a common example and there are clear coatings with similar properties.

I understand that the clear coatings applied to carbon fibre masts need more frequent renewal than a solid paint finish, but a clear coated carbon mast is a thing of beauty.

The other issue is that epoxy resins start to lose strength at relatively low temperatures. I used to fly high performance gliders and these were always painted white for this reason. There was even concern about small amounts of orange that were sometimes added to wingtips and the rear of rudders. The idea of the colour was to provide a contrast and thereby reduce the chance of midair collisions. All white gliders disappear against a background of white cloud and midair collisions are unfortunately reasonably common, nevertheless even in small areas anything other than white was outlawed by many manufacturers.
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Old 08-07-2019, 12:58   #44
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Re: Lightning Protection, pros and cons

A carbon fiber mast is just as attractive to lightning as one that is aluminum. The top of the mast is pointy and high off the water so that initially it accumulates static charge via low current flow, so the material resistance is not an issue. When the ionized channel in the air is formed just before the strike it makes much higher current flow possible. When the strike occurs the flow is a matter (more of less) of Ohms Law at work. The current into the Earth will be divided among the available paths... mast, rigging, wiring... in inverse proportion to the resistance of each path. Lower resistance, higher current. In all cases the mast is the lowest resistance and will carry the large bulk of the current. Problems of carbon composite are that it has a significantly higher volume resistivity (think 50:1) and lower damage temperature (250 vs 1000 deg F) compared to aluminum.

A strike on a carbon mast causes localized heating that punches a burned hole in the material. Aircraft deal with this by using a lightweight copper mesh in the high strike probability areas (wing and tail tips) to distribute the current over an area as it is "launched" into the carbon, reducing the heating effect.
I have thought that applying this material to the top and bottom 2 feet of a composite mast might limit catastrophic damage. Generally there is cosmetic damage and some mesh must be replaced after a strike.
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Old 08-07-2019, 13:43   #45
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Re: Lightning Protection, pros and cons

I just have hands on knowledge. For 44 yrs.I have used 1/4” grounding rod copper attached to rigging extending at least 2^ under the water, each side bow and stern and have not been hit, I did out run a water spout with copper down and recieved a good hit thru my tiller, having a drop or kick up alumlnum rudder , on my tri felt like a truck ran over my arm. I had a bad storm kick up with my dad on his tri , got to the dock, blasts all over , flash and blast , ran to the house, didn t put ground rods down and the tri got hit and blew a 2’x4’ chunk out of the hull above the water line. So I use grounding rods and hope to remain afloat, a guys sail boat locally got hit and sunk in 15 minutes. me and my grounding rods. I hope they work......
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