What do you do to mitigate lighting damage?

[kmason]

In the link GordMay provided it specifically says in section 5, "Currently, no evidence exists (other than that of the manufacturer) to substantiate the claims made about these [lightening prevention] systems. NFPA has [to date] voted down attempts by the manufacturers to create a separate NFPA standard for DAS, and there has been no U.L. approval of these devices. Until there is corroboration of the manufacturer's claims, these systems cannot be considered a genuine means of preventing the potential for property damage due to lightning."

If there is no proven device for lightening protection/prevention then insurance companies can't require you install it. All the methods for mitigating a lightening strike (except a faraday cage) is completely anecdotal and unproven.

[Paul L]

Originally Posted by Cyrus Safdari

From making Faraday cages as a kid as experiments
Kids still make em and now you can test their effectivemess by putting a cellphone inside your faraday cage and seeing how many bar it has for reception

The trick is to make sure the holes in the cage material are smaller than the wavelength you wish to block. It’s the same principle that allows you to use standard chicken wire as a RF reflector as long as you’re working with relatively low frequencies. But as your target frequency increases the wavelength gets small enough that it can sneak through chicken wire, so you need to use something tighter. But how small is small enough?

To start, we need to find the wavelength for the frequency we want to block. This can be found by dividing the wave’s speed in meters per second by its frequency in hertz. As we’re dealing with a radio wave we know it will be traveling at the speed of light, and for the frequency let’s say we want to block 2.4GHz. So the math will look like:

"So the math will look like: The rule of thumb for a Faraday cage is that the openings should be no larger than 1/10th of the wavelength, which in our case is 12.5 mm (approximately 1/2 inch).
https://hackaday.com/2018/09/26/buil...ly%20available

.

The 1/2 inch hole corresponds with approx. 2.5GHz. Nothing magic about that frequency and lightning. Also, as I understand it, the lower frequencies have far more power than the higher frequencies in a lightning strike. It will do a good job blocking WiFi
Using a typical boat oven, even with the window, or a microwave will do a pretty good job onboard. Nothing is perfect when it comes to lightning. It seems to me rules like less than 1/2in just put people off from doing the simple, relatively effective solutions.

[Oceanride007]

Think Ham Operators would know if there suppression equipment will work. In regard to Faraday Cage, a metal hulled boat, would be protection if only the cables are "opened" before they get inside, Radio, TV, solar, Mast lighting, mast transducers, etc.

Pseudo science is out there but trying different protection devices is the way to find out what works, but a boat 90% protection is still a failure in a lightening event.

[coopec43]

Apparently a school was hit by lightning today and 15 people had to be taken to hospital.

https://www.9news.com.au/national/13...2-cedee74e5b3b

[Cyrus Safdari]

Originally Posted by Paul L

The 1/2 inch hole corresponds with approx. 2.5GHz. Nothing magic about that frequency and lightning.

The point was that the smaller the holes provide the better protection and so - separately- in order to test this they used what they could which was cellphones reception and thus they picked that frequency - to test their Fraraday cage effectiveness out on a cellphone (because we can't yet induce real lightning to test Faraday cages, see?)
The same principle however applies to lightning protection: a Faraday cage must have as continuous an exterior as possible and insulated on the inside

Originally Posted by Paul L

Also, as I understand it, the lower frequencies have far more power than the higher frequencies in a lightning strike.

You'd still want as few and as small holes as possible regardless for the greatest protection

Originally Posted by Paul L

Using a typical boat oven, even with the window, or a microwave will do a pretty good job onboard. Nothing is perfect when it comes to lightning. It seems to me rules like less than 1/2in just put people off from doing the simple, relatively effective solutions.

Not sure this claim has any actual support other than a common cruisers myth. But it can't hurt so why not shove our gadgets in the oven anyway and if they live through a t-storm we can say it was because we kept no bananas aboard and witches sink too etc.

The science of Faraday cages on the otherhand is well known. Any hole weakens the Faraday effect. That big hole in you oven does indeed compromise it as a Faraday cage *because science.*

[Cyrus Safdari]

There are indeed "arrestors" which furthermore kick in automatically but the problem is that they still won't protect from the induction charge. Even if you're not directly struck the bolt will distribute an electrical jolt on every wire in everything electric or electronic and a few may even turn on by themselves if not already fried. You may not find out they're fried until much later too when they start to act up

[Paul L]

Originally Posted by Cyrus Safdari

The point was that the smaller the holes provide the better protection and so - separately- in order to test this they used what they could which was cellphones reception and thus they picked that frequency - to test their Fraraday cage effectiveness out on a cellphone (because we can't yet induce real lightning, see?)
The same principle however applies to lightning protection: a Faraday cage must have as continuous an exterior as possible and insulated on the inside




You'd still want as few and as small holes as possible regardless for the greatest protection






Not sure this claim has any actual support other than a common cruisers myth. But it can't hurt so why not shove our gadgets in the oven anyway and if they live through a t-storm we can say it was because we kept no bananas aboard and witches sink too etc.

The science of Faraday cages on the otherhand is well known. Any hole weakens the Faraday effect. That big hole in you oven does indeed compromise it as a Faraday cage *because science.*
(& Just because someone's uncle once had their electronic survive a t storm in an oven is not any kind of proof,)

Smaller holes are needed for higher frequencies. They don't provide better protection from lower frequencies. So do you claim that the bulk of the energy in a lightning strike is in the 2GHz and higher frequencies? If so I'd like to see some support. The papers I've seen show the bulk of the energy to be MHz and below. Try your posted calculation for 100MHz and see the acceptable hole size. Nothing like your advice that you need 1/2in or less on a cruising boat.

You can call putting devices in ovens or microwaves cruiser myth if you want. Having spent a significant amount of time in Central America and Panama in lightning season, and seeing dozens of cruising boats get hit by lightning, I am confident of a few things about lightning.
1. It is capricious
2. No boat is immune, including steel hulls and boats with lightning protection systems.
3. Electronics placed in ovens and microwaves tend to survive, while not much else does,

[Cyrus Safdari]

Originally Posted by kmason

All the methods for mitigating a lightening strike (except a faraday cage) is completely anecdotal and unproven.

I think it is fair to say that *preventing * strikes is bs but we've been *mitigating* damage from strikes for a long time - with Faraday cages but also with grounding. Plenty of good science there on grounding too. Indeed Faraday cages work better if grounded. There are certainly no guarantees that grounding will prevent a sinking if struck because of the infinite number 9f factors involved in determining where lightning will go on any particular boat but the fact that you're far better off grounded than ungrounded if struck really isn't debatable imho

[Cyrus Safdari]

Originally Posted by Paul L

. So do you claim that the bulk of the energy in a lightning strike is in the 2GHz and higher frequencies?

That frequency was picked by the folks who made that cage to *display the principle* that the smaller the holes the better the Faraday effect. We can't test out a Faraday cage IRL without effect. lightning so we pick what we can work with to show the priciple. Neither that frequency or 1/2" holes are any magic number, indeed the ideal Is NO HOLES at all but since you can test with a cellphone then thats a good min hole size when you pickmupmradio waves to use.. The more larger penetrations the less effective. There is enough range of frequencies in a lightning strike not to be too picky or specific. Where you want to draw your line is up to you but note you yourself say lightning is capricious as in not predictable so why risk it at all just to prove that ovens make good Faraday cages rather than just make a good solid Faraday cage with no holes or windows at all to begin with?

Originally Posted by Paul L

You can call putting devices in ovens or microwaves cruiser myth if you want. Having spent a significant amount of time in Central America and Panama in lightning season, and seeing dozens of cruising boats get hit by lightning, I am confident of a few things about lightning.
1. It is capricious
2. No boat is immune, including steel hulls and boats with lightning protection systems.
3. Electronics placed in ovens and microwaves tend to survive, while not much else does,]

I have no quibble with any of that indeed I believe the ABYC says electronics should be ina metal box but the science of Faraday cages is pretty straightforward


Se3ms to me Unless you have some particular affection for the ol' oven-as-faraday cage trick and want to risk it, 8 don't see why not make a real cage I think it is relatively simple to gin-up a full enclosure metal box with some plastic lining on the inside so why not? I use a kid's school lunchbox. Just scrape the pain't off the lid. Fits a cellphone wGPS plus charger battery and a vhf.

[Paul L]

Originally Posted by Cyrus Safdari

That frequency was picked by the folks who made that cage to *display the principle* that the smaller the holes the better. We can't test out a Faraday cage IRL without lightning so we pick what we can work with. 1/2" holes are not a magic number the ideal Is NO HOLES



I have no quibble with any of that indeed I believe the ABYC says electronics should be ina metal box but the science of Faraday cages is pretty straightforward


Unless you have some particular affection for the ol' oven-as-faraday cage trick and want to risk it, 8 don't see why not make a real cage I think it is relatively simple to gin-up a full enclosure metal box with some plastic lining on the inside so why not? I use a kid's school lunchbox. Just scrape the pain't off the lid.

Yes, the 1/2in example may have been just an example, but you then tell people in this thread that it is a requirement, something that is just not true. You match the construction of a faraday cage to the enemy you are protecting from.

Originally Posted by Cyrus Safdari
.......
Ps microvwaves and ovens work as Faraday cages only if there are no gaps larger than about 1/2", plus insulated on inside. They do sell soft sidesd metalic lined cases for electronics to block rf which also acts as Faraday cages.

Microwaves and ovens work as faraday cages because like all faraday cages they work at certain frequencies and to certain extents.

[Jammer]

I can assure you that some RF energy at 100 MHz will make it through a 1/2" opening, though perhaps not much. The ideal Faraday cage has no holes and is made of perfectly conductive material. There are commercially available screen rooms used for R&D and some kinds of radio equipment service -- we've had them at work. They use copper screen with around 25 wires per inch, and have antireflective treatments inside to further dissipate any unwanted RF.



In practice most electronics will be just fine if they are not connected to anything (such as 12vdc or external antennas) and are far (many feet) from the discharge path i.e. the mast and its ground strap.


Microwaves are pretty well shielded at their operating frequency around 2.5 GHz; if they weren't your hand would get warm if you felt around the door (and they would not meet regulatory safety standards). I think it would take a large stretch of the imagination to conclude that much energy from a lightning hit would get inside.


Lightning protection is less well understood than the OP (among many of us) might like but it is science not voodoo

[Cyrus Safdari]

Originally Posted by Paul L

Yes, the 1/2in example may have been just an example, but you then tell people in this thread that it is a requirement, something that is just not true. You match the construction of a faraday cage to the enemy you are protecting from.

Microwaves and ovens work as faraday cages because like all faraday cages they work at certain frequencies and to certain extents.

A smaller hole blocks a greater range of frequencies than a bigger hole. Your goal is to stop electromgnetic radiation as much as possible across as many frEq ranges not to for some reason optimize the hole size on the Farday cage to make the biggest possible hole. At least thats not my overriding goal lol. At 1/2 " you start picking up cellphones. This is a good max size to set because it is easily testable w cellphone but ideally there should be no holes.

IWhy be picky?unless you're really realty intent on proving ovens as Faraday cages, just buy a lunchbox Is it really such a big deal?
Things don't become tru just because they're repeated often and are conceivably possible aka have "truthiness" because it merely sounds plausible. No one has shown ovens actually work as farday cages and i for one wouldn't want to have to prove it with my gear when. I can just buy a lunchbox

[Eder]

Well heres my story of our last crossing the equator. Anyone who has done this knows the lightening storms involved in the Pacific north of the doldrums....scary.


After getting fragged left right & center for almost an hour the most experienced of our crew said" I'm going to bed".
Pretty much the most intelligent response.


fwiw myself and another spent 4 hours trying to steer around the storm...most likely extended our exposure.

[Paul L]

Originally Posted by Cyrus Safdari

A smaller hole blocks a greater range of frequencies than a bigger hole. Your goal is to stop electromgnetic radiation as much as possible across as many frEq ranges not to for some reason optimize the hole size on the Farday cage to make the biggest possible hole. At least thats not my overriding goal lol. At 1/2 " you start picking up cellphones. This is a good max size to set because it is easily testable w cellphone but ideally there should be no holes.

IWhy be picky?unless you're really realty intent on proving ovens as Faraday cages, just buy a lunchbox Is it really such a big deal?
Things don't become tru just because they're repeated often and are conceivably possible aka have "truthiness" because it merely sounds plausible. No one has shown ovens actually work as farday cages and i for one wouldn't want to have to prove it with my gear when. I can just buy a lunchbox

That maybe your goal in arguing on a CF thread, it is not the goal of someone out cruising in lightning areas. The goal is to reasonably protect backup electronics, such as handheld vhf, laptops GPS, from lightning induced energy above the level that causes damage. Nothing more. And to do this in a way that doesn't disrupt the operation of the boat.

You seem to think that the oven or microwave window negates their usefulness. Did you do the size calculation for 100MHz and below? The engineering involved does follow.

Don't make perfect, the enemy of good as so many CF threads are inclined to do.

[Cyrus Safdari]

I think you're really really, over estimwting how much cruisers optimize things...lol

If someone thinks using a oven as a Faraday cage because the ... what? Weight savings? - makes them a better cruiser somehow, far be it for me to stop them from shoving their electronics or themselves in an oven. I'll splurge on a tin box to make a real Faraday cage that I don't also need to bake a chicken in.