What do you do to mitigate lighting damage?

[Jdege]

Maybe it's just me, but I'd consider preventing the lightning from blowing a hole through my hull to be of higher priority than protecting my electronics.

[dstraton]

No reason not to do both. Zener diodes are very cheap.

[BoatBumm]

Everything I’ve read says that the various lightning protection systems do indeed make it less likely you’ll have serious damage from a strike, BUT they don’t guarantee no damage, AND the experts say that having those systems (like the metal bottle brush at the top of the mast) actually makes it more likely you’ll be hit since that makes a good path to ground.

And lightning strikes are rare. In my 50 years of sailing I have personal knowledge of only one boat that got hit. It was anchored near me in the North Channel of Lake Huron when a very strong TStorm system swept through. That was not the tallest mast there. Just bad luck. Most of the onboard electronics were fried as a result. No other damage. Mother Nature is fickle especially regarding where she sends her lightning bolts.

Anyway, I view it as a wash. The systems might give you some protection but at the cost of being more likely to get hit. Choose your poison.

[Jammer]

Originally Posted by dstraton

Apart from the issues discussed in this thread so far, I think there is a case to put a Zener diode across the positive and negative inputs into valuable electronic devices. It opens up extremely quickly and should protect the device within a certain range of lightning spike.

Zener diode or MOV? MOVs will stop spikes that are too large for diodes


We would use them both



You might want to think about putting either of them in an enclosure that is suitable for the maximum power levels involved because they can fail in ways that give off a lot of heat if you connect them to a 12vdc supply that is fused for lots of amps


Every input and output to a device can carry a surge. Antenna, NMEA2000, power, Ethernet, video camera feed, etc etc. You have to put surge protectors on all of them and connect them to a common low-resistance point.



Each input will need its own strategy for stopping a surge. On the antennas you can use a blocking capacitor and a gas discharge tube. On the power you can use a fast-acting fuse and a MOV. On NMEA2000 you can use ferrites and maybe a MOV or a pair of diodes to clamp the voltage. Or all three


Ethernet is difficult because most techniques will affect communications. Best to replace with fiber.


It all has to be engineered if you want it to improve overall safety.



I've been in labs where this stuff is tested. Red 120v outlet with the big warning sign on it and a red button a foot away to apply the surge. Configurable as to voltage and duration. We also had a high voltage wand that could be applied to other connectors and to exposed surfaces of the product. Lots of dollars spent blowing up prototypes in that lab trying to figure out compact, cost-effective ways to build a product that will withstand a surge.

[calmissile]

After reading all the posts in this thread, I feel compelled to add my 2 cents. Hopefully my comments will add some perspective to the various opinions, causes, solutions, etc.

My background is nearly 60 years as an aerospace engineer in both missile systems and aircraft avionics. Have been a 'ham' operator since the 6th grade and initially educated in Broadcast Engineering. I have been the owner of power boats most of my life but recently purchased a Columbia 45 CC sailboat that has turned into something of a project boat.

To understand the basics of lightning, I recommend watching the video which was posted earlier https://youtu.be/ww0XJUqFHXU It is not necessary to understand the math and complex material, it is the basics that are important to understand the impact of lightning on a boat. The demonstration of the Van De Graph generator with the sphere as well as the pointed rod are perhaps the most relevant portions to watch.

I have watched many lectures and videos on lightning and this is one of the best I have seen so far. From the collection of those I have watched there are some facts common to most of them.
1. Lightning is caused by an electrical voltage difference between air in the clouds and the earth (or even cloud to cloud).
2. Electron flow can be cloud to ground or ground to cloud, depending on which polarity the cloud is charged.
3. A lighting bolt is usually preceded by feeder or spider paths that do not ionize the air and hence do not give off a flash. Think of being electrically charged such as walking across a carpet and your hair stands up but no arc or spark occurs. There is enough voltage difference to stand your hair up indicating that a small current is flowing through the air but not enough to ionize the air and be visible.
4. As mentioned in some lectures/videos, these feeder strikes do not generally cause massive damage to equipment or prooperty. Overvoltage protection devices and even zeners and MOV's can generally cope with the feeder strikes. As seen in lightning videos, these feeder paths/strikes often do not even reach the ground. A good case could be made that HV voltage protection devices are a good idea and should be incorporated in all electronic devices. Not only for lightning, but any other sources that might exceed the rated voltage input to the device.
5. It is true that lightning is going to take the least resistance path to ground. It is a little simplistic to think of this in only static terms. As the lighning bolts begins its path to ground through an object, that ground may deteriorate such as melting or blowing off and the lightning bolt will then fan out to find a better return path to ground.
6. As noted in the video the feeder strikes are not what causes the massive damage, it is the ionization of the air of the main strike that provides the 'pipeline' of low resistance for the main charge which causes the flash and thunder.

So, what are the main factors determining if a boat will be struck? The point of the cloud formation that has the highest voltage difference between it and earth is going to try to find the path of least resistance to discharge its potential to ground. It is not necessarily directly below the cloud. The air is unstable and moisture content is not uniform. The lightning discharge might travel horizontally before finding a path to ground. It might even spread out like a spider web before picking its chosen path.

Lets think about this realistically. If we are on a flat ocean with a charged cloud above us, what would cause my boat to be picked out as the target of a strike? The most obvious answer is that something about the boat is making it a lower resistance to ground than the surrounding water. Lets remember that air is generally an insulator when it is not ionized. If you stick something up from the water surface that has less resistance to electricity than air, then the path for the strike has to go through less resistance to reach ground.

The best evidence of this is when trees are hit and explode (due to the water vapor in them) rather than simply striking some dirt next to the trees. Anything that pokes up from the ground is more likely to be hit than just plain soil. We also need to consider the horizontal component of the resistance path. Lightning is not going to travel horizontally unless the ultimate resistance of the path is less than the terrain immediately below it.

So what would be the ultimate protection from being hit by lightning on a boat? A submarine!

Now let's discuss some practical solutions to mitigate the damage since we don't really want to sail submarines.

First, we need to remember that the lightning energy is seeking the easiest path to the oceans surface. It does not mean that it will only choose one path. It may well split into several paths if they are available. The one path you do not want it to take is through the hull material. A hole in your boat below the waterline in a storm is not my idea of having a good time.

So what are the best measures to take to minimize the damage to the boat and the electronics. The obvious is to create a straight path from where the strike is likely to occur to a robust metallic connection below the waterline. There is a lot of debate about whether we are 'attracting' lightning by doing this. My sense is that if the lightning is close enough to strike my boat with a ground system, it is close enough to likely strike it anyway and I would rather mitigate the damage than to think I will be lucky and it will strike somewhere else.

For the sake of this discussion, I am going to not address the affects of EMP on damaging electronics other than to agree with the comments about putting critical electronics in an oven or similar box. To truly shield against EMP is so costly and impractical that in my mind it is not worth the effort. We spend millions every year protecting our missile and aircraft systems from EMP and it is not something practical for a pleasure craft. (IMHO).

I would like to point out something in the video that I find very interesting. Note that when a sphere is used as the ground, ionization of the air occurred and the charge produced a 'lightning bolt" along with the sound of the air ionizing. When he used the pointed rod, ionization did not occur. I had not seen this in other studies but find it worth exploring further. If at the top of the mast, you have a pointed rod would it be less likely to experience a lightning hit? Don't know, but would like to see some more experiments.

At any rate, it seems to me that a heavy gauge ground wire from a lightning rod at the top of the mast to a metalic point below the waterline is probably the best thing to do first. I have an aluminum mast keel stepped into a steel step and bolted to the cast iron keel. The keel is fiberglassed so I would expect a lightning bolt to blow off a small portion of the fiberglass which is a lot easier to repair than a hole in the boat.

If this were the only path the strike took, then the electronics might otherwise survive. Unfortunately, in most cases I have read about, the path the strike took was throughout the electrical system. Many cases of melted wires, motors burned up, etc. Why was this? Because the path to the ocean surface was not adequate and the current had to find other paths to get to ground! Also, please remember that using a little green wire running down your mast isn't going to carry the current of a lightning strike for more than microseconds,. It is going to vaporize much like the antennas, etc that we see were hit. The cable/wire has to be substantial for it to withstand a strike.

So what might we do to protect the electronic systems that are still connected when we expect a potential strike? One of the posters offered a solution that makes some sense. That is to completely disconnect the electronics with a double pole switch (both the power and ground leads). With an air gap of an inch to two it might prevent the voltage from propagating down all the power leads. At least it is worth thinking about.

In any case, you would not want the boats (-) power leads connected to the same place as the lightning ground (in my case the mast step/keel). That would be the point where the high voltage would propagate into the boat wiring.

The idea of adding zener diodes, MOV's etc to various electronics would probably provide some protection from feeder strikes but would do nothing against the main direct strike. It will simply blow them off the board (as I have experienced).

There is probably something to be said for grounding shrouds and stays. Again, it is only going to provide protection if there is a good solid connection to a metalic ground below the waterline. Also, remember that lightning traveling at the speed of light does not like to change direction. Therefore, the path to your ground needs to be direct and heavy duty.

Hope my 2 cents has inspired some follow on thinking about the topic and am anxious to learn of additional experiments and anecdotal results others have experienced.

[Icarus]

Originally Posted by a64pilot

Insurence
But it’s not a sure thing, I’d bet that those that have been struck are a minority,or insurence wouldn’t cover it, you would buying special high dollar lightning insurence if it were that common.

Lighting insurance?
Maybe staying on safe land would be batter., even then you might just get hit by a falling tree.

[carstendenmark]

Nicholson58, could you please specify which double switch (+/- integrated) to recommend for this purpose, for a 12/48 volt system ?

[carstendenmark]

Interesting to add MOV's into the electronics circuits for protection.


Any experiences of you guys, how to do this ?



Might blow up, though...

https://en.wikipedia.org/wiki/Varist...rfail_full.jpg

[Hermia II]

Originally Posted by jen1722terry

Yet another interesting thread on lightning.

Never thought of the jumper cable-shroud-water idea.

We cruise mostly in Maine and the Canadian Maritimes. Lightning is not the issue that it is further south, but we get some storms with pretty good fireworks.

Got me thinking: in marinas we use a corrision "fish," basically a 1 lb. piece of zinc on a piece of coated SS cable with a clip to the backstay. Would this function as lightning protection also?

We do carry jumper cables we could also use, but if the fish works, why not use it?

Cheers. Everyone stay healthy.

Stainless steel is not a very good conductor, and electricity from a thunderbolt is in a hurry. Do carry about six jumper cables Forestay, Aftstay and 4 shrouds. It is a very small investment, easily set up when needed.

[alanvee]

Originally Posted by Lasivian

I figure it's not "if I get struck by lightning" it's "when I get struck by lightning".

What is the best solution to deal with this threat?

Thanks

Is this relating to loss of electronics being zapped? If so, it seems to me that what’s needed is a piece of GPS kit that can be brought out of a lightning safe place and can run off a self-contained power source in the event everything else has been fried. How about this?
5 inch chart plotter with own GPS antenna designed to run off 5 volts consuming very little power. It will run for 14 hours off a phone bank type power pack and if the phone pack is one of those with a small solar cell built in it can be kept topped up. Keep everything associated with the plotter in something that represents a Faraday Cage and it will be safe from a strike. Plotter is made by Onwa Marine, model KP38S, only thing I didn’t like about the plotter is that after around 30 seconds it goes to a stand-by state but wakes up if any button used. This is a power saving feature and why it can run 14 hours from one charge. Comes with an 8 to 48 volt to 5 volt converter which has a 5 volt output to a USB socket (the plotter supply cable is terminated with a USB plug)

[Jammer]

Originally Posted by carstendenmark

Interesting to add MOV's into the electronics circuits for protection.


Any experiences of you guys, how to do this ?

https://www.mouser.com/pdfdocs/Litte...72014final.PDF

Might blow up, though...

https://en.wikipedia.org/wiki/Varist...rfail_full.jpg

Sometimes they fall on the sword to save the downstream electronics. Sometimes they fall on the sword and the electronics downstream is burnt to a crisp anyway. MOVs have maximum surges they will survive, see the application guide I linked above.

[carstendenmark]

I wonder if this 2-pole switch will work, to shut off power to the 12V sensitive devices during a thunderstorm ?

I don't know the gap of the internal conductors when shut off, but I can split one in pieces. (Price is 2 US$ where I am now.)

Sounds like MOV's makes more damage than good, when overpowered...

[Basil]

Hi I hope the attached video shows the power of lightning, your protection onboard needs to be able to withstand this type of force. If you think hanging chains or battery cables hung over the side can handle this force , great, or your fluffy mast mounted lightening defector good luck.
https://youtu.be/LCdIM67g3mY

[calmissile]

Originally Posted by Basil

Hi I hope the attached video shows the power of lightning, your protection onboard needs to be able to withstand this type of force. If you think hanging chains or battery cables hung over the side can handle this force , great, or your fluffy mast mounted lightening defector good luck.
https://youtu.be/LCdIM67g3mY

Give us a break! Your fake lightning video doesn't impress anyone but the gullible.

[Sailmonkey]

Originally Posted by Basil

Hi I hope the attached video shows the power of lightning, your protection onboard needs to be able to withstand this type of force. If you think hanging chains or battery cables hung over the side can handle this force , great, or your fluffy mast mounted lightening defector good luck.

https://youtu.be/LCdIM67g3mY

That “Lightning” looks an awful lot like primacord running down the shoreline to initiate some explosives beneath the surface.