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Old 25-03-2018, 19:09   #1
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LIGHTNING DETAILS -Risk Management

Many tales on CF about damages from Lightning Strikes, but nothing specific about the conditions that caused them?

1...What type of Lightning caused them?
2....Steel, Wood or Fiberglass hull?
3....Aluminium or Wood Masts?
4....At Sea or in a marina, plugged in?
5....What did this type of Lightning hit?
6...What damages were done?
7...Tips to prevent damages if at Risk.

After +40 years at sea, I have never had any damages, despite many times in severe lightning storms
(So i figure I'm due ).
..so I want to learn more about the specific details, conditions and prevention

My study so far
http://stormhighway.com/types.php
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Old 25-03-2018, 20:03   #2
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Re: LIGHTNING DETAILS -Risk Management

There's a bunch of science for this in the radio (cellular phone) industry.

Key take aways to consider:
1) Most lightning strikes occur in regions that get a lot of thunderstorms; statistically, this has much more to do with the probably of loss than protective measures, materials, etc.
2) Structure height is the other main factor however the best available data now shows that the likelihood of a strike doesn't increase much beyond around 500 feet
3) Protective measures are expensive and nowhere near 100% effective. In areas with lots of storms they are financially worthwhile

Separately, talking with insurance adjusters, far more losses are wind related than lightning related
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Old 25-03-2018, 20:29   #3
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Re: LIGHTNING DETAILS -Risk Management

Thanks Jammer,
I'm specifically interested in marine related lightning risks.

Are our networked Nav/AIS systems more vulnerable?

Am I protected enough with a steel hull?

If no. should I just turn off all Nav/ electronics when a Sumatra hits near Singapore?
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Old 25-03-2018, 20:56   #4
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Re: LIGHTNING DETAILS -Risk Management

Quote:
Originally Posted by Pelagic View Post
Thanks Jammer,
I'm specifically interested in marine related lightning risks.
I wish you well in finding solid data. I offer informed conjecture, based on dealing with the aftermath in land-based situations.

Quote:
Are our networked Nav/AIS systems more vulnerable?
Probably not, because the +12v power system is a sufficient vector to do loads of damage. It is possible for manufacturers to "harden" the power and networking connections by adding ferrite chokes, metal-oxide varistors, optical isolators, and so on, but this would add $10-$20 per assembly which most manufacturers aren't willing to do. A good question to ask is which, if any, of the mainstream marine electronics makers have incorporated this sort of protection into their products.

Quote:
Am I protected enough with a steel hull?
There is no "enough" when it comes to lightening protection.

Quote:
If no. should I just turn off all Nav/ electronics when a Sumatra hits near Singapore?
It won't help.

My parents are weather geeks and had a windex on their house. It got hit by lightening, the hit and the resulting fire did $20k damage. I could not find the wire that used to go to the windex. It was vaporized. There was a hole in the propane line 20' away from the strike due to inductive effects. Phone lines, around 15' away, had the insulation melted and failed a couple weeks later.

Substantially all electronics in the house were destroyed.

I can tell similar industrial stories about cell sites that took a direct hit. Despite being "hardened" a bad strike can more or less toast all the electronics.

Now, if you have gear that is shut down, disconnected, carefully wrapped in two layers of thick copper foil, and stored away from the mast, it will be ok.

The marine environment is not materially different for this.
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Old 25-03-2018, 21:13   #5
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Re: LIGHTNING DETAILS -Risk Management

Quote:
Originally Posted by Pelagic View Post
Many tales on CF about damages from Lightning Strikes, but nothing specific about the conditions that caused them?

1...What type of Lightning caused them?
2....Steel, Wood or Fiberglass hull?
3....Aluminium or Wood Masts?
4....At Sea or in a marina, plugged in?
5....What did this type of Lightning hit?
6...What damages were done?
7...Tips to prevent damages if at Risk.

After +40 years at sea, I have never had any damages, despite many times in severe lightning storms
(So i figure I'm due ).
..so I want to learn more about the specific details, conditions and prevention

My study so far
Lightning Types and Classifications
I have read about folks who, while underway, put a handheld VHF and handheld GPS in the oven with the hopes of isolating them only to bake them the next day.
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Old 25-03-2018, 22:54   #6
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Re: LIGHTNING DETAILS -Risk Management

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.
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Old 25-03-2018, 22:54   #7
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Re: LIGHTNING DETAILS -Risk Management

So far, this is what I am finding from NOAA weather safety tips
http://www.lightningsafety.noaa.gov/tips.shtml

Less likely to get lightning strikes at Sea than on Land

If lightning strikes on Water, it radiates out horizontally at a shallow depth, so swimmers are vulnerable if within a few 100 ft.

On land, most electrical / wiring damages result from major strikes to power grids that surge towards adjacent homes ...They now recommend you switch to internal power (generator/invertor) to avoid this.

(So on a boat, are we not safer if off the grid? (Unplugged at Marinas?)

As Jammer said, if you get a direct strike on land, surge protectors and your ground wires will probable not prevent serious damages.

Why makes aircraft safe flying near or thru thunderstorms?

What about at Sea (as a better conductor)...with my whole steel hull as a ground?

If lightning struck the stainless Mast Caps of my wooden Masts, would it not just travel down the path of leat resistance....i.e the heavy rigging to hull and dissipate in salt water?
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Old 25-03-2018, 22:57   #8
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Re: LIGHTNING DETAILS -Risk Management

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Old 26-03-2018, 10:04   #9
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Re: LIGHTNING DETAILS -Risk Management

I have always been instructed that one reasons electronics are more susceptible to damage is that they have a soft switch that turns them on and off. This is not the physical disconnection that an actual mechanical switch creates. The theory (and it's a good theory) is that if you have a mechanical switch before the electronic equipment you wish to protect, you are less likely to fry the electronics if hits.

One must of course recognize that a powerful, direct hit may very well do all sorts of strange things regardless or protective measures. On the other hand, a mechanical switch may save something as opposed to not having it. It guess it's a crap shoot so all one can really do is take as many precautions as one can sensibly take and the rest is up to luck.

I often wonder if a wooden mast would help but then, an antenna at the top of the mast or metal stays would defeat any benefit.
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Old 26-03-2018, 10:18   #10
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Re: LIGHTNING DETAILS -Risk Management

My boat took a lightning strike the week I bought it, fortunately I had insurance. The strike hit the VHF antenna on the main mast, vaporizing it. I found little bits of the base and the mount on the deck afterwards, which is what clued me in to what happened as I was not aboard at the time. The boat was docked and plugged in to shore power at the time. The nearby restaurant claimed that they lost a couple of TVs when the strike happened.

Most of the electronics were fried and needed replacement. Strangely, the masthead wind instrument survived. No hull damage, but many electrical circuits needed replacement. Batteries were fried too, as was the inverter/charger. All told, the repairs and replacement gear came to around $30k.

I've read that, and apparently insurance statistics back this up, multihulls are about twice as likely to get hit than monohulls, even in the same marina. https://www.boatus.com/seaworthy/mag...ning-facts.asp

To answer your specific questions:
1...What type of Lightning caused them? - Regular thunderstorm type lighting - sorry, silly question ;-)
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? - See above
7...Tips to prevent damages if at Risk. - Live somewhere with lower lightning incidence ;-)


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Old 26-03-2018, 10:21   #11
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Re: LIGHTNING DETAILS -Risk Management

Quote:
Originally Posted by Pelagic View Post
Thanks Jammer,
I'm specifically interested in marine related lightning risks.

There's no such thing as 'protected' from lightning on a boat you can just get a little "safer";all the gadgets claiming to reduce lightning are frankly baloney. Turning things off won't protect them either, lightning jumps and there's enough energy to fuse engine bearings so never mind anything else ... but turning them off is the best you can do and doesnt' cost anything so, why not?

On the positive side, years of accumulated data by the US Coast Guard shows that the biggest threat to boats is inattention and drinking. Lightning is no where near the top of the list of things to worry about.
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Old 26-03-2018, 10:21   #12
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Re: LIGHTNING DETAILS -Risk Management

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.
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Old 26-03-2018, 10:28   #13
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Re: LIGHTNING DETAILS -Risk Management

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Why makes aircraft safe flying near or thru thunderstorms?

The same reason that birds can sit on an electrical wire and not die -- the circuit is not complete.

Lightning jumps around it doesn't just go where you expect. And it does damage as it goes -- chains or other metal things can actually explode (such as the large SSB bronze plate ground attache to the hull below waterline), fiberglass cooks and becomes brittle etc.
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Old 26-03-2018, 11:04   #14
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Re: LIGHTNING DETAILS -Risk Management

Quote:
.....

Am I protected enough with a steel hull?

If no. should I just turn off all Nav/ electronics when a Sumatra hits near Singapore?
I've been on a friends steel hull who was hit by lightning while offshore in Central America. The hit started a fire in a wiring harness in the engine room and fried some electronics. Steel hulls seem to statistically be less prone to lightning damage, but not immune.

I think there are two things you can do concerning lightning.
1. Keep backup nav electronics in a cage, aka the given.
2. Stay out of high lightning areas in the thunderstorm season.
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Old 26-03-2018, 11:07   #15
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Re: LIGHTNING DETAILS -Risk Management

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If lightning struck the stainless Mast Caps of my wooden Masts, would it not just travel down the path of leat resistance....i.e the heavy rigging to hull and dissipate in salt water?

"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!
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