What do you do to mitigate lighting damage?

[peter57]

[QUOTE=Chris Cringle;3289538]Sailing south down the west coast of Central America, there were forty boats is our informal "fleet". Off Costa Rica, the "lightning capital" of the west coast, 27 of those boats were damaged by lighting.

Do you know if any steel hull yachts were affected by a hit or suffered field damage from a yacht hit nearby?

[Paul L]

[QUOTE=peter57;3290326]

Originally Posted by Chris Cringle

Sailing south down the west coast of Central America, there were forty boats is our informal "fleet". Off Costa Rica, the "lightning capital" of the west coast, 27 of those boats were damaged by lighting.

Do you know if any steel hull yachts were affected by a hit or suffered field damage from a yacht hit nearby?

A few years back when we did Pacific central America, a friends steel hull was struck off of Nicaragua. It took out a fair amount of electronics and started a nasty fire in an engine room wiring harness.

[Nahbrown]

We unplug the microwave and throw our hand held GPS, Ipad, radio and sat phone into it. The unpluged microwave acts as a faraday cage to protect those items so we can still communicate and navigate.

[Cyrus Safdari]

Ground Mast and all large metal fitting within 10 feet
Engine already grounded via prop shaft

Starting from farthest below:

- Mast compression post base is connected via 1/2" bolt to copper flatbar running 7 feet aft below under hull exterior at about 5 ft underwater;

- higher up; 2x3 ft long copper flat bar outside along waterline each on Port and stb hull sides midship, for grounding stanchions & shrouds there and anything metal larger than a breadbox which can accumulate charge ie bronze seawater distribution manifold in the head too. These two copper straips are themselves connected to the mast compression post base and so to the 7ft strip running under the hull.

- Then there is the rubrail running al9ng topside. It is wooden but has a decorative brass half oval 1/2 wide stock that goes almost the entire length of the exterior hull on each side, mounted about 7" below the toerail. I use that as a common bus to ground the remaining stanchions, pushpit and pulpit railing by using long 3/8th copper bolts that gothrough the rubrail at intervals along the hull sides, to both secure the rubrail on the hull and to attach terminals for grounding wires along the way. The rubrail common bus is also connected to the three ft long copper strips running along sides at water surface level and also copper strip running under the hull

Wiring: uses awg 6 and marine tinned wire and tinned copper eye terminals. The 1/2" copper bolt ends used to secure the copper strips externally are esaily peened to make sure the nuts don't come off. The wires are kept off hull interior by about an inch.

If hit i am sure my electronics and vhf antenna will be toast just b ecause of the induction chargecal9ne even if not a direct hit. Not much to do about that as I am not about to spend thousands to EMP harden the boat so I carry spare VHF ant. Even disco nected devices can be ruined

(It is important to remember what NOT TO bond ie: windlass. If there is a short to the metal casing any smaller grounding/bonding wire you attach to it will become energized with a lot of power and will burn up. So no bonding the windlass, or things connected to it ie chain or anchor rollers. )


I was of the "nevermind lightning not much you can do anyway" school but became a convert to grounding after seeing a boat that had been struck with, left with multiple holes just above waterline and along prop shaft, so I figure better safe than sorry. If you're out in the middle of an electrical storm waving a 40f5 conductor in the air, and no lightning protection..., just seems silly and unnecessarily risky. The trick is to try to avoid building up charge and giving a clear path for electricity to tye water surface so the charge does not punch through the hull and or your body.


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.

[kmason]

Lightening protection is a misnomer. You can't protect from it. If it hits your boat or close by you are almost guaranteed to have some damage. Think Localized Electro-Magnetic Pulse or LEMP. Even without touching your boat or by riding down the mast, through some jumper cables and into the water, your boat has been subjected to a very large LEMP. This alone will cause current to travel down every copper circuit in your boat and may cause problems.

Electricity takes the path of least resistance and the only way to stop electrical flow is to provide a gap in the circuit. If you drop a cable into the water have you increased your chances of being hit? I mean, haven't you just provided a clear circuit from the tallest object (your mast) to ground? Same thing with grounding all your thru-hull fittings to the mast. Why do you think electrical code requires an earth ground on houses? It's not to protect your house, it's to protect the electrical lines from from absorbing a lot of electricity. Path of least resistance.

Think about this (I think I read it a long time ago on these forums)...

Insurance companies do not require any kind of lightening protection or mitigation on your boat/yacht. Nada, zip... nothing you can do will reduce your premiums on your insurance. If there was some magical, lightening repellent on the market your insurance would make it mandatory equipment in order to get a policy.

[a64pilot]

Originally Posted by kmason

Insurance companies do not require any kind of lightening protection or mitigation on your boat/yacht. Nada, zip... nothing you can do will reduce your premiums on your insurance. If there was some magical, lightening repellent on the market your insurance would make it mandatory equipment in order to get a policy.

I base a lot of my belief that there is no effective solution on this. If something worked, then either you would get an insurence break for having it, or be required to have it, or not be covered for a strike.
It’s like having old rigging as an example, many insurence companies won’t insure you with old rigging, because of course old rigging is more likely to fail and cause a claim.

[Paul L]

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.

Where are you coming up with a 1/2in max hole for protection of a lightning strike in an onboard Faraday cage?

[GordMay]

Originally Posted by a64pilot

I base a lot of my belief that there is no effective solution on this. If something worked, then either you would get an insurence break for having it, or be required to have it, or not be covered for a strike...

Marine Insurance companies, typically, don’t offer discounts (or require installation) for lightning mitigation systems, for a number of reasons, including (but not necessarily limited to):
- They have no practical way to determine if your boat has an effective system. There are no certifications for marine lightning protection designers, installers, nor inspectors.
- They have no practical way to determine if your system has been adequately maintained.

See “Lightning Protection” ~ Inland Marine Underwriters Association (IMUA)
➥ https://www.imua.org/Files/reports/L...rotection.html

Originally Posted by Paul L

Where are you coming up with a 1/2in max hole for protection of a lightning strike in an onboard Faraday cage?

See ➥ https://www.cruisersforum.com/forums...ml#post3284294

[Cyrus Safdari]

Originally Posted by Paul L

Where are you coming up with a 1/2in max hole for protection of a lightning strike in an onboard Faraday cage?

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

.

[GordMay]

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"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.

That calculation is based upon the speed of light.
But, what is/are the frequency(s) of a lightning induced RF pulse, that we're discussing?

[Cyrus Safdari]

Originally Posted by kmason

Electricity takes the path of least resistance and the only way to stop electrical flow is to provide a gap in the circuit. If you drop a cable into the water have you increased your chances of being hit? I mean, haven't you just provided a clear circuit from the tallest object (your mast) to ground?

No. Look at it this way. Like you say an air gap is the best insulation ( nevermind induction by emp) and that lightning bolt is coming out of literally thin air miles of atmosphere so really your little bit of chain tossed into water isnt a big contributor or encourager of the strike. The charges aee simply too massive to care.

[Cyrus Safdari]

Originally Posted by GordMay

That calculation is based upon the speed of light.
But, what is/are the frequency(s) of a lightning induced RF pulse, that we're discussing?

Ill leave that to enginneers
Speed of light and speed of electricity are the same.
Anyway point is, less gaps the better and that big window in your oven is not helping

[grantmc]

Originally Posted by Chris Cringle

... On my boat, we had a small icon of Saint Barbara, the patron saint of lightning strikes, tacked to the mainmast. We were not damaged.

This statement sounds like the most scientific suggestion of all.

I think that the idea of lightning protection on a boat is pseudoscience. All the anecdotes of this worked, or that didn't almost always neglect to state rig and hull materials. Even the spelling of the word causes issues for many.

[Jammer]

Originally Posted by grantmc

I think that the idea of lightning protection on a boat is pseudoscience.

Perhaps some of it is.

Lightning hits produce sudden, severe, memorable damage whether on sea or land. This affects people's perceptions. The science, though sound, is complicated and there is a random element involved in how lightning will behave. On land there have been well-controlled experiments with buildings, radio masts, etc. deliberately built in areas with frequent storms so that the outcome of various mitigations can be assessed in an analytical way. As a result some of the general principles are understood as are techniques for things like antenna and electric wiring in/on a mast.

Not much work done on fiberglass boats with aluminum masts so we have to extrapolate. There is plenty of evidence to show that grounding the mast will reduce the likelihood of getting a hole in the hull from a strike.

It becomes difficult and expensive -- very difficult and expensive -- to protect the electrical and electronic components in any useful way. Much of the work really belongs in the electronics themselves through the use of ferrites and MOVs on power and data at the entry point to each device. Figure $2 per individual wire and you're looking at over $100 parts cost for a chartplotter manufacturer to do this (once you add up NMEA2000, HDMI, Ethernet ports, power, NMEA0183, remembering that most of these have multiple wires requiring protection).

Do it outside the device and you're adding connectors, bulk, cost, possible failure points, and an installation that most marine service techs will not be able to understand and certainly won't be able to maintain properly. There are things like running fiber optic cable in place of Ethernet to the radar, and fiber optic cable in place of NMEA2000 to the wind instrument, that would make a great deal of sense and dramatically improve the survivability of the chartplotter if the manufacturers would support them. But they don't, and weatherproof ethernet-to-fiber converters are expensive, and NMEA2000-to-fiber converters are AFAIK nonexistent.


Some of the most useful information out there is best practices for radio transmitters. Though they are on land, a transmitter building with a mast next to it and a fence around it has remarkable similarities to a boat with a cabin, a mast, and lifelines:


http://www.repeater-builder.com/ge/l...lbi-39067a.pdf


There are common-sense things like using an RF surge protector where the VHF antenna lead exits the mast. They're $100 and take an hour of skilled technician time to install. How many boats have them? It adds up. You should perhaps have one for your other antennas too (AIS, second VHF, DSC, backstay, etc). How many thousand dollars are you willing to spend to improve the odds of your electronics surviving a hit?

[skyhawk]

everytime I see this trhead pop up, I keep thinking a good idea might be some sort of emergency disconnect
....like one of those red e-stop mushroomed shaped buttons you can slap with a hand or knee....
Storm gets close....Hit the e-stop and open relays to disconnect everything. Antenna cables, power to each device, etc...

I know it's not an absolute but disconnecting can sometimes help (as I experienced in my lightning event many years ago)

does such a thing exist?