Lightning Protection

[Barker45]

Greetings All,

We will be going with a wooden mast and synthetic standing rigging like amsteel. What would your opinions be on a sail boat with no metal aloft? Seems relevant to me since so many golfers get hit with only a few feet of meal golf club and most courses have tall trees. I am no expert in this area at all and am just curious. (the boat is wood too) Thanks.

[sandy daugherty]

After sustaining a considerable amount of damage to my cat as a result of a lightning strike, I have done a lot of research on the subject. The reason there is nothing on my present beloved is simple; nothing works. The best scientific evidence has led noted "authorities" on fire prevention (NFPA, OSHA, FAA) to retract their previous firmly held positions, and the wide assortment of snake-oil cures continue to emerge with great fanfare and dissappear in the night after the first strike.

We know how to attract lightning, and a strike in close proximity has clearly understood effects on pricey electronics. I choose not to attract lightning. No strike shield for me. (sorry, Richard Woods, I have to disagree with you on this ONE thing!)

As for that fuzzy little wire ball at the top of your mast, it works to conduct charges both ways, and that includes the big one. Besides, it's useless if it isn't higher than anything else on you boat, and you'll get zapped (at least by an astute surveyor) if your VHF antenna sticks up above it!

All you can do to improve your level of comfort is to chose to believe something works, anything. Even jumper cables. What did that song say?

"I don't care if it rains or freezes
'long as I got my Plastic Jesus
riding on the dashboard of my car..."

I'm stepping on toes here, but I believe that Lightning Protectors, (AND radar reflectors) are dangerous; they give skippers a false sense of security when they might otherwise be more cautious.

In the mean time, you'll find me smugly nestled among a forrest of taller masts, with a farraday bag full of emergency gadgets.

[SailFastTri]

Originally Posted by Spammy

Another related question: carbon versus aluminum masts. I've heard that a lightning strike to a carbon mast might destroy it. anyone with experience?
Rocky

Just one data point: My CF mast was not damaged after being struck. What does it take to melt a stainless whip antenna? There is no explaining lightning.

BTW - there is stainless rigging attached at the collar (barely showing in the image) at the headstay furler and from that collar there are jumper stays connecting down to the mast base. The mast base is grounded to a Dynaplate underwater directly below the base. I think the charge jumped to the rigging and traveled down the rigging on multiple paths to the water. We were not aboard at the time.

There was a thorough inspection done on the rigging, mast, and hull (hauled out for that) and no damage. Most of the boat's Raymarine nav electronics and 2 out of three tank gages had to be replaced, including some engine harness wiring that contained relays and diodes. The rigger who did the inspection has over 30 years experience and said he's seen all kinds of stuff, but there's no predicting lightning.

BTW I sent all Raymarine stuff in for test as a networked system and Raymarine gave a very nice deal on replacement/upgrade for newer generation gear at "repair" prices.

[Tropic Cat]

Sandy, genuinely sorry to hear you sustained damage. When were you struck? How deep was the water you were in at the time?

My latest theory is that Cats are struck more often than monos because we're in shallower water at the time. Shallower than a mono can comfortably handle.

In my case I had to replace all electronics and clean up the mast to remove the black carbon from the lightning strike. For the record, my VHF antenna was on top of the mast and was vaporized.

[Barker45]

Originally Posted by sandy daugherty

After sustaining a considerable amount of damage to my cat as a result of a lightning strike, I have done a lot of research on the subject. The reason there is nothing on my present beloved is simple; nothing works. The best scientific evidence has led noted "authorities" on fire prevention (NFPA, OSHA, FAA) to retract their previous firmly held positions, and the wide assortment of snake-oil cures continue to emerge with great fanfare and dissappear in the night after the first strike.

We know how to attract lightning, and a strike in close proximity has clearly understood effects on pricey electronics. I choose not to attract lightning. No strike shield for me. (sorry, Richard Woods, I have to disagree with you on this ONE thing!)

As for that fuzzy little wire ball at the top of your mast, it works to conduct charges both ways, and that includes the big one. Besides, it's useless if it isn't higher than anything else on you boat, and you'll get zapped (at least by an astute surveyor) if your VHF antenna sticks up above it!

All you can do to improve your level of comfort is to chose to believe something works, anything. Even jumper cables. What did that song say?

"I don't care if it rains or freezes
'long as I got my Plastic Jesus
riding on the dashboard of my car..."

I'm stepping on toes here, but I believe that Lightning Protectors, (AND radar reflectors) are dangerous; they give skippers a false sense of security when they might otherwise be more cautious.

In the mean time, you'll find me smugly nestled among a forrest of taller masts, with a farraday bag full of emergency gadgets.

Greetings Sandy,

Thank you very much for your candid and clear reply. Our boat is also a catamaran, Wharram design. With the exception of a Faraday bag we will hope for the best and know we are safer out there than on the road.

Really, thank you again.

Cheers.

[sandy daugherty]

Here's my post on another Forum:
"My PDQ 32 was struck in a slip off the Potomac River in 1999. The windex and vhf antenna blew up, and the antenna cable in the mast melted. Every circuit board on board was fried, including a Street Pilot III in a drawer, but we found no discernible exit point. One witness said the entire boat glowed. A second said that a fluorescent fixture on his boat that had quite working years before came on and continues to work. Another (drunk and peeing in the water in front of my Cat) said God told him to cast his glasses on the concrete dock and crush them under his foot. So much for witnesses. A sailboat on stands in the yard fell over on the owner's pickup, who had just been sued for divorce.

Markel American's Yachtsman Policy replaced every single item with new, using the installer I specified. Radar, chart plotter, radios, autopilot, chart cartridges, instruments, handhelds, et. al. I can't speak highly enough of them, certainly worth the premiums I paid, plus whatever premiums I will pay in the future too! Do the math.

Paul Fleury, a leading authority on Marine electrical systems, lightning strikes (and consultant to PDQ), assured me that no "Lightning Protection Device" would have mattered. Still in doubt, I did a lot of research myself, and came to the same conclusion. I was working for the NTSB at the time and had the resources for a definitive examination of the claims, counter claims, good science and bad from all over. Sources that sounded like they should know better plainly didn't. Arguments about preventing an electrical differential through static discharge equal but do not overcome arguments against creating an electrical path for lightning. In short, no one has an answer, YET."

I should add that, for the price of a cup of coffee, I was able to consult with several other (truly brilliant) Professional Engineers and Accident Investigators at the Board, who came to the same conclusion. They had (if you will forgive the understatement) some experience in the matter.

Further: The boat was in 9 feet of water, tied to a galvanized steel framed floating dock riding up and down with the tide on concrete filled 12" diameter steel pilings driven to a heavy clay substrate in a wide creek off the Potomac river. Salinity was low. Adjacent residential areas had underground utilities that were knocked out in the storm. I believe that there were multiple strikes in the area. The boat had Stainless steel plates fitted over the bows, and they were normally submerged an inch or two, possibly providing a path to ground. My boat was thirty feet away from a monohull sailboat with a 10' taller mast.

Remember, it is NOT the actual path of the lightning that fries electronics, it is the massive EMF generated that does the dirty. So a Farraday Cage better NOT be grounded lest it become a real oven. Think of the heat generated by a metal wire as it vaporizes.

[sandy daugherty]

Barker 45: Its just my opinion, but I think you are still at risk for the VHF and masthead light wiring running up your mast.

[zeehag]

the only boat i know of that had protection from lightning and was owned by nasa scientist was hit by lightning when all the unprotected boats were not-----will take 6 mos to 1 yr to repair the damage from hit number two----4 yrs ago was hit and took 6 mos to repair......i just have a cat---ther eis no recorded words about a cat being hit by lightning---and we sailed through many storms pof the lightning variety just this past june off florida-----we didnt get hit-----there is no rhyme nor reason to lightning----but after seeing the beneteau 50 get hit the second time made me not want to get protection for my boats -- seriously....

[DaveOnCudjoe]

My thought is to insulate the boat as much as posible from ground. Research shows that as a strike forms a streamer rises from the earth to meet it and initiate the main discharge. You can't protect yourself from the strike but you may be able to prevent the streamer from directing it to you. There are lots of variables and lots of points of view, that is mine. So far(25yrs)so good. Dave

[neelie]

Anyone have any theories as to why Cats are more susceptible to lightning strikes?

Or is simply because that statistic (from insurance companies) is skewed because Cats make more claims due to sustaining greater damage?

While I accept that lightning protection is impossible. Can one not make a case for for providing a path to ground (e.g. Strikeshield) in order to minimize damage?

This practice is done on some tall buildings.

I'm still contemplating the Strikeshield line of products.

[GordMay]

Originally Posted by DaveOnCudjoe

My thought is to insulate the boat as much as posible from ground...

And that "insulation" will exceed that of 5 to15 miles* of air?

* That's how far the lightning may have travelled to get to the boat. Air is an excellent insulator.

[lancelots]

Lightning is one of the most deadly natural phenomena known to man, with bolt temperatures hotter than the surface of the sun and shockwaves beaming out in all directions.

In an electrical storm, the storm clouds are charged like giant capacitors in the sky. The upper portion of the cloud is positive and the lower portion is negative.
The electric field becomes more and more intense, so intense, in fact, that the electrons at the oceans’ surface are repelled deeper into the ocean by the strong negative charge at the lower portion of the cloud. This repulsion of electrons causes the earth's surface to acquire a strong positive charge.
All that is needed now is aconductive path for the negative cloud bottom to contact the positive earth surface. The strong electric field, being somewhat self-sufficient, creates this path.
When the electric field becomes very strong, conditions are ripe for the air to begin breaking down. The electric field causes the surrounding air to become separated into positive ions and electrons

The importance of this separation is that the electrons are now free to move much more easily. The ionization of air or gas creates plasma with conductive properties similar to that of metals. We can view the ionization process as "burning a path" through the air for the lightning to follow.

A path is not created instantaneously. In fact, there are usually many separate paths of ionized air stemming from the cloud. These paths are typically referred to as step leaders, objects reach out to the cloud by "growing" positive streamers. These streamers also have a purplish color and appear to be more prominent on sharp edges

After the step leader and the streamer meet, the ionized air (plasma) has completed its journey to the earth, leaving a conductive path from the cloud to the earth. With this path complete, current flows between the earth and the cloud. This discharge of current is nature's way of trying to neutralize the charge separation. The flash we see when this discharge occurs is not the strike, it is the local effects of the strike. Any time there is an electrical current, there is also heat associated with the current. Since there is an enormous amount of current in a lightning strike, there is also an enormous amount of heat. This heat is the actual cause of the brilliant white-blue flash that we see.

After the original strike occurs, it is usually followed by 30 to 40 secondary strikes. These strikes follow the path of the main strike, the secondary strike can occur while the flash from the main stroke is still visible or after the flash from the main strike ends, making it appear that the main strike is flickering.



The purpose of lightning rods is often misunderstood. Many people believe that lightning rods "attract" lightning. It is better stated to say that lightning rods provide a low-resistance path to ground that can be used to conduct the enormous electrical currents when lightning strikes occur. If lightning strikes, the system attempts to carry the harmful electrical current away from the structure and safely to ground.

The lightning can strike and then "seek" a path of least resistance by jumping around to nearby objects that provide a better path to ground. If the strike occurs near the lightning-rod system, the system will have a very low-resistance path and can then receive a "jump," diverting the strike current to ground before it can do any more damage.
Lightning rods only become relevant when a strike occurs or immediately after a strike occurs.

Regardless of whether or not a lightning-rod system is present, the strike will still occur.

After lightning strikes the ocean, there is an electric potential that radiates outward from the point of contact which can also cause damage and death

Surge protectors won'tsave your electronics if lightning strikes you need a lightning arrester on the circuit. The arrester uses a gas-filled gap that acts as an open circuit to low potentials, but becomes ionized and conducts at very high potentials. If the lightning hits the line you are protecting, the gas gap will conduct the current safely to ground.

However a Faraday cage is much better protection, the metal cage will shield objects within the cage when a high potential discharge hits. The metal, being a good conductor, would direct the current around the objects and discharge it safely to the ground.

An oven does this nicely if it is connected to ground (remember to make sure the door is electrically connected to the body). And in conjunction with a quality lightning rod set up, may help to protect your boat, your electronics and you.





“This information is edited from other sources and does not constitute electrical advice”.

[Vick Moore]

I agree with zeehag. After 20 years owning Morgan 41 with NO lightning strikes, installed a bronze grounding plate, and guess what, we were the best ground around and got nailed. Good point was that "only" about $8,000 damage to electronics, wire in the mast, etc. and NO hull or personnel damage. Water under the hull boiled pink for a few minutes, killed a bunch of shrimp. After repairs, added one of those bottle brush thingies on the masthead, which is supposed to diffuse the buildup of positive ions instead of concentrating them. So far, no hits and the boat next to ours took a shot! My new catamaran came with one attached. I believe!

[TabbyCat]

Originally Posted by Woods Designs

This topic came up on another forum, but since it is such a major problem, especially for multihulls, that I thought it was worth posting here as well.

I suspect that more cruising multihulls are hit by lightning than capsize. But who thinks about the former before going offshore?

Anyway, this is what I wrote

"First visit Marine Lightning Protection Inc.

see the photo on the home page of a catamaran sunk after being hit by lightning, June 20th 2008

Then go to Strikeshield Lightning Protection Systems for Sailboats — Strikeshield Lightning Protection Systems for Sailboats

For the solution that I used after being hit.

Sail in the tropics in the wet season or on the east coast USA right now and you will hear dozens of stories of lightning strikes. With "luck" you'll even be hit yourself.

I sailed up the east coast of the USA in 2003 and met 2 other English boats doing the same. All three of us were hit by lightning.

Later in Panama we were anchored with a group of 12 boats. In one storm 6 were hit. Not us, we had a Strikeshield system fitted, or were lucky.

I write more about my own lightning strike on the article pages of my website"

Woods Designs Sailing Catamarans

Richard Woods of Woods Designs

Richard, came across an old post. Wondering if Strike Shield has gone out of business? I can't find them anywhere!

[Mr B]

I own a Cat, Its totally isolated from the water by about two metres,

Only the anchor chain is in the water, Its connected to plastic inside the chain locker,
I dont have an anchor windlass to connect it to anything metal on the boat,
I do have a 12 metre aluminium mast, But it is also isolated by the two metres from the water,
So is a 12 metre mast fully isolated from the water any more suseptical to getting hit by lightning, than one thats connected via electrics to the anchor Winch and Grounding via the anchor,,

Then again, Planes get hit by lightning and they are not earthed,
Looks like Pot Luck to me whether you get hit or not,


Brian,