Lightning strike second time

[sailaway78]

Over the weekend my across the canal neighbor got his boat hit by lightning. This is a 50' Benny, and is the second time it has been hit. Do not know the extent of damage this time, other than all electronics and wiring are fried. Last time it got hit, they had to do extensive hull repair, including pulling the keel. This time he had what he considered the latest, greatest and best lightning protection. One of those brush thingys on the mast, grounding and the whole schmere. This guy is a NASA engineer, and has available to him all available knowledge on the subject. There are two other sailboats within one hundred feet of him, so I guess it just basically comes down to being in the wrong place, at the wrong time.

 

[Cpt. Jon]

Wow, what bad luck. My boat was struck once before in it's slip while still owned by the previous owner. I still need to replace the anchor light and probably the wiring. He said it was a grounded mast, but doesn't think it is grounded any more meaning whatever was connecting the mast to the keel was fried. It's back to that old debate about whether it's better to be grounded or not... Lightning scares the bejesus out of me lately. We've had a lot of severe thunderstorms through here this year. I was fishing last weekend and heard thunder and started the boat and headed right in, no question. A severe thunderstorm came up fast and we ended up losing power for a few hours... at least I got to power the house up with the genny and put a load on it and test it all out in case of any more serious power outages/storms.

 

[Bob J.]

Curious, has anyone seen or heard of any studies that show the frequency of hits & damage between a keel or mast stepped boat?

Bob

 

[sailaway78]

Keel or mast stepped

I have read a lot of reports, by so called experts, including quite a bit by the UofFl. The only thing they agree on is to disagree. There are just as many studies I have seen that say ground as say don't ground. As I said in the origional post, this guy works for NASA, and should have all info. at his finger tips. Yet, his boat got hit, and two others very close to it were not touched. Don't know about the Hunter next to me, but mine is not grounded. I can see nothing positive to indicate to me that it will help. And lightning scares the crap out of me too. Got caught a few weeks ago about 30 miles offshore in a line of nasty thunderstorms, with a lot of lightning. NOAA was saying seek shelter, but there was no shelter. Other than getting beat up a little bit, no problems. But it was SCARY.

 

[Ross]

Re: Keel or mast stepped

When you consider all of the years that we have observed lightning it would seem that if there were a pattern we would have identified it by now. I think that it is completely random in both the where and the how strong of the strikes.

 

[zeehag]

i keep telling nice n easy that it is the kat that kept us from the lightning hitting us then as we traversed in the thick of it--was soooo scary i had to hide under the kat---a friend jokingly said that no one has ever known a kat to get hit by lightning----that friend and i , in all our silliness, agreed bubbadaboatkat is a potential anti zap kat hat with yet 9 lives to live before he gets to be the hat with 9 more lives in him----
sooooooo---since there is no scientific evidence to the contrary, i keep saying he is my protection---pooor kitty----but--i havent ever heard of any kitties being hit by lightning----and there is absolutely no explanation for our not having been hit during the lightning storms we went through----so far from any form of protection and in the midst of a war between the gods of the sea and our guardian angels----with a kat on board.....sooo--was it the guardian angels protecting us or was it the potential anti zap kat hat working his charms for us-----i wont leave home without him ....LOL---gooooood kitty!!!!!!!
but it is weird that one boat in an area gets slammed twice and the others donot----isnt it!! maybe kat should have gone over there and said hello.......

 

[Capn Dave]

NASA knows the brushes don't work

Florida Power and light tried them also and published a report on their dismall performance.

However, some people have claimed success. They claimed first to discharge the cloud. When that was proven impossible, they claimed to prevent a strike from occurring. It was just snake oil. These people were making a buck on wire bottle brushes. Various branches of the U.S. government have tested several multiple point arrays over the years without any success. One report was completed by the Office of Naval Research, NASA, and US Air Force in 1975.
A 1,200 foot tower at Eglin AFB, was fitted with a multipoint system and sustained eleven hits in three months.
Five were photographically recorded while seven other strikes were monitored, using NASA's magnetic links, as having had strikes in the 30 to 48kA range. The report also contains a video lightning strike sequence from a monitor showing NASA's Kennedy Space Center 500 foot meteorological tower, equipped with a multipoint array, being hit by lightning.
As the height of an object is increased, the number of strikes increases. This was proven in the middle of this century with testing at the Empire State Building. Most of the strikes to this structure were caused by upward streamers triggering the strike. A more recent test of multipoint arrays was done in the late 1980's by the FM. The FM report also concludes that the tower arrays under test were struck and damaged.The report further includes photos of the video tape of the strike, and the NASA magnetic links current measurement for one strike was 8 kA for one down conductor and 10 kA for the other. Other damage to the facility was listed together with eyewitness accounts.
Few array suppliers will agree whether it prevents a strike 100% or just minimizes the chances of a strike. Another argument is whether to ground the array and how important the ground is to the array operation.
Some of the arrays on the market consist of small rounded brushes which when hit, splatter molten metal as far away as 10 meters. This can be a fire hazard. The FAA report quotes the eyewitnesses to the August 27,1989 strike to the Tampa ATC Tower: Asparks like the slag you get when arc welding."
Mother Nature produces a large variation of strikes. The larger strikes will have larger E fields, and the stepped leaders will be longer. This means the larger strikes will overwhelm the array and upward streamers will reach out and grab the stepped leader anyway. Perhaps the array will slightly delay the streamer, making another target (if there is one) more attractive? Actually it's the KAT HAT

Fair Winds
Dave

 

[MrBee]

He got hit because his boat is grounded the best compared to the others ??? quickest route to the water. Just a thought here.
Everyone can do what "Think" or "Feel" is the best answer for them. I ain't wasting my time or money on Grounding all the stuff on the boat. I'll save that money for IF I get hit, then use it to replace parts.
Lightning is so fast and random I don't really think it takes time out of it's busy schedule to pick a target.
Put a 4 leaf clover under the Mast and Say 5 Hail Mary's .

Bee

 

[zeehag]

He got hit because his boat is grounded the best compared to the others ??? quickest route to the water. Just a thought here.
Everyone can do what "Think" or "Feel" is the best answer for them. I ain't wasting my time or money on Grounding all the stuff on the boat. I'll save that money for IF I get hit, then use it to replace parts.
Lightning is so fast and random I don't really think it takes time out of it's busy schedule to pick a target.
Put a 4 leaf clover under the Mast and Say 5 Hail Mary's .

Bee

i still like my potential anti zap kat hat ..LOL

 

[kloudie1]

My boat was hit at the slip about 5 years ago. It is grounded from the factory, has a deck stepped mast, and is the tallest mast around for about 150 yards. Some pine trees in the area are a bit taller, but their grounding systems look a little substandard. Blew apart the stern light bulb (glass sand and shards inside the Aquasignal 25 housing) , the “Reverse Polarity” light bulb on the AC panel (pieces scattered 10 feet away on the table), and erased the VHF antenna (missing and assumed to be in bottom of slip; anchor light two inches away was fine) and the VHF radio (looked fine but was not) . Blew open a couple of 12 V breaker cases (Nav lights and steaming light) but the breakers still worked. The triac that ontrols air conditioner fan speed failed to high speed only. An internal fuse in the old Raytheon LORAN failed but the thing still worked fine after replacing the fuse. No alternator or other electronic damage.. There were obvious burn tracks on the back of the breaker panel, where the tracks went from the blown breaker cases to the AC ground (green wire) . The green wire on this boat is not connected to DC ground nor is it connected to the mast ground. The DC ground is connected to mast ground. I feel lucky that the damage was so light, and that I was not aboard! Probably not a big strike.. Last summer when I did a bottom job, the keel barrier coat was flaking off strangely .. I suspect that the strike may have vaporized some water locally as it left the keel ( where all the DC grounds tie together) through the paint.. Strange stuff!

 

[higgs]

One certainty with lightning - anything can happen. The bottom line is that no one really knows - grounded or not. We do know that the rigging provides a faraday cage so being killed by the actual strike is highly unlikely.

Life is a dangerous thing.

 

[walt]

Seems that multihulls are about twice as likely to get a strike as mono hulls
http://www.marinelightning.com/catamaran/index.html#BoatUSStats
Multihulls generally are NOT grounded (i.e., no large metal underwater structures) and it looks like being twice as wide is more important than grounding or not.

One point about a Faraday cage. A Faraday cage is something like a hollow metal box. If current passes through the metal box, an electric field will not develop across the box because it is metal. So if you are inside the metal box, you do not see any electric fields despite whatever electric field "storm" is going on outside. A car with windows makes a degraded Faraday cage but apparently still a reasonable one – not so good as your cell phone still works. Calling sailboat rigging a Faraday cage is in my opinion a stretch as the rigging alone likely does little to contain electric fields. However, containing side flashing with a well bonded grounding system does likely reduce electric fields and I couldn’t really call this a faraday cage but it would have the same (but reduced) effect.