LIGHTNING DETAILS -Risk Management

[Cadence]

Originally Posted by clownfishsydney

A friend was sailing up New South Wales coast when hit. Details as follows:

1...What type of Lightning caused them? From the sky (ha ha). Normal lightning whatever that is called.
2....Steel, Wood or Fiberglass hull? Fibreglass
3....Aluminium or Wood Masts? Aluminium
4....At Sea or in a marina, plugged in? At sea
5....What did this type of Lightning hit? Mast
6...What damages were done? Fried all electronics and damaged engines
7...Tips to prevent damages if at Risk. Stay away from lightning? Moor close to other boats? Who knows, nothing I suspect.

Out of curiosity, was the rigging bonded. I've always wondered, does it help of invite lightning? I'm sure the are many threads and opinions on this. I have had boats both ways and I think I've just been lucky.

[chris95040]

Originally Posted by Cadence

Out of curiosity, was the rigging bonded. I've always wondered, does it help of invite lightning? I'm sure the are many threads and opinions on this. I have had boats both ways and I think I've just been lucky.

Yeah, that's a common question. Lots of people have different answers and I don't know which to trust.

One thing I've heard is that bonding can actually reduce your odds of being hit.
I guess before a lightning strike occurs, the charge in the clouds impresses an opposing charge on the ground below? Pointy things up high will get that opposing charge built up faster, so the potential between them and the cloud will be greater than the potential between the cloud and ground. By bonding the pointy thing to the ground around it, you've made it "invisible" to the lightning, its got no more potential than the ground around it, and therefore no more likely to get hit. Of course, it's still _closer_ to the cloud, which is maybe why grounded radio antennas still get whacked over and over.. (They do, right?)

Anyways, I really don't understand lightning, just relaying what I've heard.

[ArmyDaveNY]

Originally Posted by chris95040

YAnyways, I really don't understand lightning, just relaying what I've heard.

I don't think anyone truly understands lightening. Some experts may have a basic understanding of parts of it, but there seems to be more that we don't know than we do know. It works in mysterious ways and always seems to surprise us.

[Cadence]

Originally Posted by ArmyDaveNY

I don't think anyone truly understands lightening. Some experts may have a basic understanding of parts of it, but there seems to be more that we don't know than we do know. It works in mysterious ways and always seems to surprise us.

Treat it like golf. Head for the 19th hole at the first sign of lightning.
I guess the theory about bonding is to provide it with the easiest path to ground and the shrouds acting as a faraday's cage. I'm can't say I'm crazy about that wire running inside the boat to the grounding plate. I might feel better with a metal hull which I assume the shrouds are automatically grounded at the chain plates? Any thoughts from metal boat owners?

[JPA Cate]

Hi, Pelagic:

Rumor, in that I didn't see this unfortunate fellow, but heard about him from a friend.

1...What type of Lightning caused them? Thunderstorm with many strikes
2....Steel, Wood or Fiberglass hull? Steel,
3....Aluminium or Wood Masts? ?
4....At Sea or in a marina, plugged in? on mooring
5....What did this type of Lightning hit? ? assume, masts, but don't know
6...What damages were done? don't know
7...Tips to prevent damages if at Risk. He was struck 3 yrs. in a row on that mooring

#2

1...What type of Lightning caused them? Seasonal thunderstorm
2....Steel, Wood or Fiberglass hull? Steel "Spray" replica, taller masts next to it
3....Aluminium or Wood Masts? ?
4....At Sea or in a marina, plugged in? Marina, don't know if plugged in
5....What did this type of Lightning hit? Masts (ketch rigged)
6...What damages were done? All electronics lost, no other damage
7...Tips to prevent damages if at Risk.

#3
1...What type of Lightning caused them? Seasonal thunderstorm
2....Steel, Wood or Fiberglass hull? Vinylester, foam, carbon fiber
3....Aluminium or Wood Masts? Aluminum
4....At Sea or in a marina, plugged in? Tied up at a dock
5....What did this type of Lightning hit? Mast
6...What damages were done? All the electronics (~$25,000 to replace)




I think it may have been the EMP that took out the steelie's electronics

As to #7, preventive tips, Pelagic, Jim made a lightning deflector from a bit of rigging wire, mounted at the masthead, that we hear (on the VHF) dissipating ions. We haven't been struck, but I'm not at all sure there's a causal relationship there. More like a hope. You might send Jim a PM for a proper physicist discussion of what may be happening, it's above my understanding level.

Ann

[Pelagic]

Originally Posted by Ozifrog

Lightning Facts: An Analysis of Lightning Strikes >> Scuttlebutt Sailing News

This article is quite factual with some statistics.
Hope you learn something. I did.

My cat was struck in Guatemala (rio Dulce)
Every electronic device aboard was grilled. Radar, pilot, wind instruments. AIS VHF touch screen, you name it.
Next time I go to a lightning prone area, I'll disconnect absolutely everything.

Thanks Ozifrog, that helped a lot to put things in perspective....
Did you read the more detailed link that was attached to yours?
http://www.boatus.com/seaworthy/maga...ning-facts.asp

Great stuff!

Ironically after reading about the steps to a strike... "Leaders and Streamers"..... It may be the one time... NOT...to have Positive thoughts! [emoji2]

[GTom]

There are a few lightning topics already on CF, from those I learnt that there is no real protection against the hit, you can only reduce the damage. E.g. keep valuable not used/backup electronic equipment in a Faraday cage/box. Disconnecting stuff doesn't help, the EMP of a nearby lightning fries a completely isolated handheld VHF/mobile phone too. Actually I can imagine if my neighbor in the marina takes a hit my instruments fry too, without being in the actual lightning path.

Cats, bilge keelers need to pay attention on conduits to ensure the path of lightning to the sea.

[Basil]

Hi
I am in Asia an this is lightening central,
In my observations mast height makes no difference, but carbon fibre masts do seem to get hit more often, I was in a anchorage when three boats got hit one at least twice, while I was not struck as such I did find I had damage to a number of electronics including the alternator.
You could fee the crackle in the air at the time.
I have seen boats on anchor an in the marina struck.
In one case a boat on anchor was running his generator an this stopped in mid stroke causing major damage. A lot of damage is not discovered until months later as further electronics fail for no reason .
As for protection a friend had his super lightening protector unit which he had purchased at the top of his mast, this still remained after he was struck ,but both his outboard motor had gone along with most everything else.

[David Sandowich]

All very good and accurate information. My contribution is simple.. My boat a Catalina 42 was struct twice with in one year neatly tied to the dock in front of our home. There were, within 50 yards higher structures. Result both times... all electronics fried plus more as expected . No hull damage. Mast is keel stepped so I believe that is a plus. My friends want to park their boats at my dock this summer to hopefully get their electronics upgraded!

[thunderhoof]

I suggest that you should not disconnect only a portion of the electronics in a given bay or locker. If you physically disconnect only your most expensive gear connected to a distribution block you are still inviting lightning strike current to flow through the area and the Electromagnetic pulse may do plenty of damage.
A high current fuse on the supply of each distribution block, with a lighting arrestor well connected to the keel or hull plate on the load side of of the fuse may help you survive a strike. Remove the fuse before things get serious. The arrestor will give some protection if you don't remove the fuse.
A good fuse for the purpose is type ANL, it can be removed by loosening two bolts and leaves a good sized gap when gone.
Also, I think a good place to keep your battery operated radio and GPS should be in your sock drawer - literally. Someplace not near wiring, rigging or plumbing. Placing the items in a metalized container could only help.

[Olddan1943]

Originally Posted by thunderhoof

I suggest that you should not disconnect only a portion of the electronics in a given bay or locker. If you physically disconnect only your most expensive gear connected to a distribution block you are still i.

Remove it from the NEMA circuit and disconnect the antenna.

[Mr B]

I was sitting in my kitchen, The fridge started jumping across the floor,
The light fitting above my head exploded out of the ceiling, It wasnt turned on,
I lost a few light fittings that werent turned on, TV was kaput, Fridge was dead,
The switchboard was hanging off the wall, Melted,
Lightning had hit the mains taking out 200 odd houses,
I was at the end of it, so wasnt very badly hit, Other houses lost the lot,

My boat before I bought it had been hit by lightning in Fiji,The wind instrument wasnt working,
I have just found the wiring was fried, But it was hidden deep inside the linings,
The connector was fried, Melted wires,
It was on a swing mooring and isolated from the water,
Rope to the swing ball mooring,
The mast is 2 metres from the water line,

So I have no idea on what makes lightning hit one boat and not another,

Planes get hit flying across the sky, So being earthed out dosent seem to make a difference, either,

[Pelagic]

Originally Posted by GTom

...You can only reduce the damage. E.g. keep valuable not used/backup electronic equipment in a Faraday cage/box.

When I bought my boat, the PO had a portable Garmin GPS inside a heavy tinfoil bag.

Is that a suitable Faraday Cage/Box?... If No, how do you make one?

[leftbrainstuff]

Originally Posted by chris95040

"Electricity follows the path of least resistance" A popular and hugely misleading statement!

Current will flow through *all* available paths in an amount proportional to the resistance of that path.

Say you hook up a battery to a light bulb, but you wire it up with two parallel sets of wires. One set of wires is copper, the other is aluminum. If electricity "followed the path of least resistance", you'd expect all of the current to be flowing through the copper wire (since it is about twice as conductive as aluminum). In fact, that is not true. In this example, I guess about a third of the current would be flowing through the aluminum, the rest would flow through the copper.

Don't think that because you've given lightning a great down conductor that the other components in your rigging won't also see some current!

Lightning is very high potential (voltage). High voltages will tend to move down the outside (or skin) of paths to ground. These high voltages also jump gaps and arc which causes most of the damage to electronics.

Current flows within a conductor. I've never read anything on the amount of current in lightning. To weld bearings you need significant current. Welding with an earth through a transmission is one way to weld bearing balls / rollers and races. It's often not obvious until some time later when bearings get noisy.

[puffcard]

My boat has been hit twice. The 2nd strike happened just after I finished fixing the last item from the first hit. I just replaced the AM FM radio and turned it on for five minutes to test went home and the boat was struck that night. I've also personally was hit while working on a boat that was sitting on the hard high and dry.

Answer to your specific questions: For my boats hit
1...What type of Lightning caused them? - Regular thunderstorm in Va
2...Steel, Wood or Fiberglass hull? - Fiberglass
3...Aluminium or Wood Masts? - Aluminium
4...At Sea or in a marina, plugged in? - Marina, plugged in to shore power
5...What did this type of Lightning hit? - Masthead VHF antenna
6...What damages were done? - Everything electrical was toast
7...Tips to prevent damages if at Risk. - Unplug anything you can and don't hold on to the rigging.

Time I was personally hit. I was working on a boat that was sitting on the hard, blue-sky everything good. I was doing the final assembly on a hull valve. When I heard a loud crack then at the same time I was getting thrown across the v-berth and a 3ft green arc was coming off my wrench to the hull valve. Well that really shook me up my heart was beating out of my chest and I was just sitting there thinking what to do. So I started rummaging through the boat to find something to calm my nerves. I found an old beer, after drinking that beer I went and told the guy I was working for what happened. We went back and couldn't find any damage to the boat. That small sailboat was sitting high and dry, no shore power and the thru hull wasn't bonded. Guess I was lucky.

It seems with lightning protection there's a lot of different theories. but you have to realize that lightning is traveling through air for miles and a little air gap across a switch is not going to slow it down one bit.

The most damaging lightning hit I've ever seen was in St Michael's Maryland sitting at the Crab Claw eating crabs. When a summer squall came through. There was a 38-foot Hughes sailboat anchored in the river when lightning hit the boat it sank in just 5 seconds. It seemed that Hughes when they built the boat, they built it in two halves and then joined the two halves together after the moldings were done. Well what happened the lightning hit the rigging came down the back stay and forstay and split the boat right in half.