Lightning

[TheDragon]

I bought my boat in Panama in 2019 and it sat on a mooring there for 2.5 years through innumerable thunderstorms without being hit, let alone its previous five years there, along with many other boats in that marina and elsewhere in Panama. But I met three boats that were hit, and have followed the saga of the catamaran Parlay Revival on YouTube that got hit at anchor near Panama City a few years ago and then again recently in Costa Rica, each time suffering major electronics damage. I am not convinced there is any way to avoid or prevent a lightning strike, but when crossing Panama Bay one night got enveloped in a massive set of thunderstorms so wrapped all electronics in many layers of heavy tin foil and put them in the oven as the bare minimum, plus disconnected my VHF and chartplotter. I believe my mast is grounded to the big zinc bolted to the hull, but not sure (should ask Pacific Seacraft), but I also have a heavy-gauge set of car battery cables that I put one on each upper shroud and the end in the sea. All probably useless in case of a direct strike, but possibly helpful in case of a streamer or nearby strike. Then I sat in the companionway as far from metal as possible for several hours.

All by way of introduction to this article in NYT on a remarkable study of strikes filmed in Brazil. Of course we have long known of the positive streamers generated from the ground by intense thunderstorm clouds overhead (I have even experienced the standing-up-hair phenomenon while hiking in mountains in a storm), and that a strike usually connects to one of them, but these guys caught it all with a ultra-highspeed camera that takes 40,000 images per second, allowing literal millisecond analysis. There is a vid in the article and the paper linked below has more detail. Amazingly the final strike took a 90 degree turn as the connection to a streamer from a chimney was made, even ignoring a nearby higher lightning rod. Scary stuff.

One of the Luckiest Lightning Strikes Ever Recorded

Brazilian researchers captured on camera the brief moment when lightning rods on buildings released an upward discharge to attract incoming lightning.

www.nytimes.com

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101482

 

[kent_island_sailor]

I used to do a lot of lightning repairs. The most common one was that the dock or nearby boat got hit and the boat I was working on was damaged by the lightning coming in via the shore power connection.
Direct hits varied between trivial damage and a sunk boat. I was standing about 50 feet away from a boat that took a direct hit once, their VHF antenna landed on the dock black and smoking The radio and the antenna were the only damage. A common repair was pretty much all the electronics. If the mast was not grounded to the keel, a lot of really bad things could happen, including one we worked on that blew a hole in the hull and sank.

Good reading on lightning: http://www.marinelightning.com/Siedarc.htm

 

[TheDragon]

So maybe being on an isolated mooring rather than in a slip with shore power connection was good?

 

[Kurtz]

I love this video on dealing with lightning. It makes sense

 

[TheDragon]

Here's another company claiming to offer a system to prevent lightning strikes, apparently costing 15k per "antenna". Sounds like voodoo to me.

Its operating principle is based on compensating, stabilizing the existing electric field in its environment, generating the conditions of factors so that no electric discharge is produced in the protection area, in this way it cancels the formation of the ascending tracer, neutralizing the lightning, draining the electrical charges to ground, in harmless milliamps.

UN DISPOSITIVO DIFERENTE A LOS PARARRAYOS – SERTEC S.R.L.

sertec.com.py

 

[Lost in Translation]

In tower construction for radio systems, there is a lot of knowledge and data now on lightning. One long lived standard is Motorola R56. I’ve never seen it come up in marine discussions but seems relevant with a lot of money going into it over the years for public safety radios etc across the USA. A big emphasis is grounding and tower builders place many wires, rods, and minerals into the earth to achieve low levels of resistance from the tower to ground. I’m a big believer in grounding from my work in the industry.

One difference for some sailors is fresh water. I read a Univ of Florida study that tested different lightning solutions for boats. It’s posted somewhere on these forums IIRC. I remember them finding there was little that could be done in fresh water as the grounding is so much worse in fresh.

 

[TheDragon]

Just not sure I believe what the guy in that video is claiming. Just to start, being hit by lightning every second month till he got the "ionic dissipator" on the mast is hard to believe. I have a Namibian couple who were my mentors in Panama over my 2.5 years there and who basically live on their boat in the San Blas in Panama where they charter for a living, and have been there for almost a decade now. As far as I know they have never been hit, and I am not aware of any "preventive" measures they take. It seems just to be luck.

 

[Ron Swanson]

Best discussion on lightning I've heard: https://www.59-north.com/onthewindpodcast/290-jeff-thayer

 

[low bum]

I wonder about lightning and dyneema rigging. Some sources say it's more protective (current just doesn't "go there" because it's not attracted) and some say less protective (heat and sparks can melt it off.) I asked John Franta and if I remember correctly he didn't know of an instance where it has happened yet.

 

[low bum]

If the mast was not grounded to the keel, a lot of really bad things could happen, including one we worked on that blew a hole in the hull and sank.

Good reading on lightning: http://www.marinelightning.com/Siedarc.htm

So for a deck stepped mast... It blows a hole in the deck with probable resulting dismasting? Or it runs down the wire to the chainplates? I guess anything that can happen will.

 

[kent_island_sailor]

So for a deck stepped mast... It blows a hole in the deck with probable resulting dismasting? Or it runs down the wire to the chainplates? I guess anything that can happen will.

You would want to try to ground the mast somehow. Grounding the chainplates would also help. If there is a compression post under the mast you could run a wire down that to the keel, assuming it is an external lead keel. I am not quite sure what happens when an encapulated keel is used for a ground.

 

[kent_island_sailor]

I love this video on dealing with lightning. It makes sense

Those things and the bottle-brush dissipaters sold for big $$$ that are actually 25mm bore gun cleaning bristle brushes AFAIK do nothing at all.

 

[low bum]

You would want to try to ground the mast somehow. Grounding the chainplates would also help. If there is a compression post under the mast you could run a wire down that to the keel, assuming it is an external lead keel. I am not quite sure what happens when an encapulated keel is used for a ground.

Internal ballast - lead pigs in concrete, glassed over. Maybe I'll just clamp some jumper cables to the mast and drop the other end over the side if things start to snap crackle pop.

 

[longhorn]

Here's another company claiming to offer a system to prevent lightning strikes, apparently costing 15k per "antenna". Sounds like voodoo to me.

Its operating principle is based on compensating, stabilizing the existing electric field in its environment, generating the conditions of factors so that no electric discharge is produced in the protection area, in this way it cancels the formation of the ascending tracer, neutralizing the lightning, draining the electrical charges to ground, in harmless milliamps.

UN DISPOSITIVO DIFERENTE A LOS PARARRAYOS – SERTEC S.R.L.

sertec.com.py

That's the device that the Wynns covered in a recent video with Just Catamarans:

 

[Diarmuid]

Lightning: It does what it wants.

The potentials and current involved are so far outside normal electric system parameters, there's really no way to prevent it from harming your boat or the devices attached to it. Lighting writes its own rules and warps physics to its needs: it send feelers ahead of it to ionize (normally-insulative) air, then the big hammer chases that plasma tube to ground. You know those gigantic forks in the sky? That's lighting following a self-generated path(s) of least resistance, changing its mind partway down and jumping sideways thru the air 4 miles. So it gets halfway down your shrouds and decides that engine block looks tasty ... ya think it isn't gonna detour there, possibly using your oven as a waypoint?

I live on absolutely flat and treeless prairie, near 12,000' mountains that catch a lot of T-storms. Our house electrical system is entirely self-contained, which involves big metal poles sticking up in the sky, then fat wires running into the house. We've hammered 8' copper ground rods everywhere, bunged Delta lightning pots in ten different places, added clamping-type surge arrestors to the sensitive gear ... but I know much of that is mere propitiation. "Please, O Lord of Thunder: I beg you, do not fry my shit, kthnx have a cookie." Someday a direct hit will probably liquify the wind turbine, melt off the wire insulation, chase a conductor underground to my house, and blow all the watering caps off my forklift batteries. Because it can. Because it wants to. Because a silicon oxide varistor is just an amuse-bouche to a direct lightning strike, a story to tell the lightning grandkids, about as effective at blocking lightning's progress as that squirrel that throws itself under the wheels of your SUV.

I mean, ya gotta try something, and maybe it even helps, more or less. But we shouldn't be surprised when it doesn't, and we return to our boat to find a smoking puddle where the VHF used to be.

 

[Kurtz]

Those things and the bottle-brush dissipaters sold for big $$$ that are actually 25mm bore gun cleaning bristle brushes AFAIK do nothing at all.

I've done a bit of work dealing with static electricity build up on industrial machinery, Earthed bars of sharp pointy strips of metal certainly dissipate a local electric field. The spark length of an accidently disconnected earth wire to Earth is scary.

 

[Lost in Translation]

University of FL research: https://ufdcimages.uflib.ufl.edu/IR/00/00/76/10/00001/SG07100.pdf

Nothing normal is going to safely carry a full strike as Diarmuid says. The charge has made it across miles of nothing and a few feet or meters of any material that is less conductive won’t stop it. The goal is just to try not to attract it more than anything else around.

 

[justsomeguy!]

The spark length of an accidently disconnected earth wire to Earth is scary.

I was getting 3/4 inch+ discharges from my body to any piece of metal inside my old Mac25 during some threatening weather.
Attached the end of a roll of solder to a shroud and dropped the rest of the roll to the ground.
Worked.

 

[TheDragon]

That's the device that the Wynns covered in a recent video with Just Catamarans:

Thanks for that. I still don't buy it and certainly would not BUY it. Best comment on that video.

"There has got to be a way to mimic this in a marine lab. Put small boats in the water one with the device and throw out lightning."

 

[kent_island_sailor]

I was getting 3/4 inch+ discharges from my body to any piece of metal inside my old Mac25 during some threatening weather.
Attached the end of a roll of solder to a shroud and dropped the rest of the roll to the ground.
Worked.

Our old standby when I was a kid was jumper cables from the upper shrouds hanging in the water. I think they can carry a lot more current then solder