Lightning, and what to do about it

[Pegu Club]

Originally Posted by onestepcsy37

Q.
Do you have any technical citations to back up this approach? As I understand it, EM radiation blows electronics unless they are in a Faraday cage/shield.


A.
i have not one shred of scientific evidence. it was not even my 'approach'. it just so happened that furuno fused both wires when they built their navtex. i am merely relating my one and only experience with lightning. but wait. theres more....

some, but not all, of our interior bulbs were burned out. our p&s nav lights were also burned out, but not the stern light.

anything i had connected directly to the battery bank (six 6v golf carts) was undamaged. they were the cpt autopilot, the adler barbour fridge, the 600w inverter, and the solar panel. all except the solar panel were fused only on the positive wire.

in the words of pee wee herman -

what does all this mean? I DONT KNOW!!!!

Mecka Lecka hi Mecka Hiny ho, Jomby knows...

[Wallaby]

It is indeed a matter of luck, or lack thereof, yet having been struck by lightning in the past, I believe proper grounding and bonding saved the vessel from sinking. Every bronze thru-hull was an exit point--we knew that from the scorch marks in the anti-fouling.

The EM radiation killed anything with a circuit board, and knocked out five new AGM Lifeline batteries. Had it happened offshore...

Nowadays, I have surge suppressors on radios and crucial instruments. Offshore, I carry an emergency epirb, vhf radio, and battery-powered mini-chartplotter in the microwave. And yes, I carry charts, a compass and a sextant.

[PineyWoodsPete]

30 years ago we were 1st time sleeping aboard our little Sea Pearl 21 cat-ketch with a midship canvas enclosure - a bit like in a coffin - in Captiva I., FL's Ding Darling wildlife sanctuary. At dawn, awakened by thunder and lightning and an approaching black cloud, I pulled the closed-cell cockpit cushions inside and we sat on them on the bottom.

Soon there was a tremendous, deafening crash, and coming to our senses the garbage bag next to mizzen mast tube was afire, which I quickly threw into the cockpit's dense rain. Smelled burning plastic, and saw the 3" or so diameter PVC mast tube bases melted fore and aft, but no water coming in. The cockpit compass card was blown off, the handheld VHF non-op. We got the little 3HP Suzuki started and began motoring toward the canoe rental skid a half-mile or so distant when the boat began to settle into the water, but none seen above the double floor. I pumped the P&S 30 gal ballast tanks dry on the way.

Massive hull damage apparent on pulling the boat out, with a 1" exit hole in the outer hull bottom below a spare anchor adjacent to the mizzen mast tube, but no inner liner damage above it; a large exit hole above waterline adjacent to foremast, with spongy glass about 18" radius around it; multiple bronze fasteners in the leeboard rubbing strakes blown out. The foremast top took the strike and was damaged, and there was an arc-burn on the mizzen mast from the main boom's end about 6" away. Every thing metallic on the side shelves was damaged, with some pinhole exterior exits.

We were somehow not physically affected by this cage of lightning surrounding us, but with the replacement boat, heavy auto jump-start cables clamped onto a 1' 3/4" copper tube joined the boat kit...

[Montanan]

Well lets lighten up this thread.

[CLady]

Ah, Lightning.
Just make sure you have taken very good care of your Karma.

Some years back I was sailing south from Nicaragua approaching Isla del Cocos off Costa Rica. The convection lightning storms typical of the Intertropical Convergence Zone were in full bloom. The worst was at night with heavy rain and little wind--very slow going and approaching the island from the north. The rain was so intense, the radar had difficulty "seeing" the island, so it was prudent to stand off until daylight to safely enter Chatham Bay.
For hours the lightning struck the water all around the boat every few seconds--the thunder was deafening loud at the same time as the bolts occurred--it was right on top of the boat. Crouched under the hard dodger, stripped of any metal such as harness d-rings/shackles, I made a Karma review. After that, I concluded that we all are not in charge of 'scheduling' of our 'time'. We ultimately aren't in control. Just put your handheld devices in the galley oven, (acts as a Faraday cage hopefully), in case of a strike to the boat. After the storm passes and you realize you are granted 'more time', just keep all of your promises you made to all of the Gods while you were surrounded by lightning. That seemed to help my fate as since that occasion, I have survived several since--out in the Pacific encircled by huge intense squalls, record rare unforecasted synoptic low off the Washington coast that made the front page of the Seattle Times, off Hawaii,(Oahu), in the Chesapeake, in the South Pacific, and off Brasil.

'Wishing you good Karma

C Lady

[fguptill]

Walking around in Miami airport a few years ago I noticed that its buildings are equipped with hundreds of rooftop lightning rods. It seems likely that someone might have confirmed their utility before incurring such a large expense.

[wholybee]

Originally Posted by Cpt Pat

Woe is me. All is lost. It's up to fate. Don't look both ways before crossing the street because: "when it's my time to go, it's my time."

Fatalistic rubbish. You'd think no one here has heard of Benjamin Franklin.

I worked as a broadcast engineer, and we'd take direct hits on our towers hundreds of times a year with no damage. The coax from that tower lead into a building full of electronics more delicate than anything on your boat.

What's the difference between a broadcast tower and a sailboat mast? There's water under a boat.

Bonding. Grounding (a relative term - seawater is more conductive than the dirt under the broadcast tower). Surge protection.

Do those three things right, and you shouldn't have a problem. Or, you can just blame the capricious lightning gods for smiting your boat with fire from the sky. Everyone in the 17th century would agree with you.

Also a broadcast engineer for 20 years. Towers get hit all the time, and with millions of dollars of equipment at risk, lighting protection has been well studied and works.

That said, the bonding on most boats is far too small, it needs to *huge* to prevent damage to equipment.

[atoll]

you could fast charge your new Lipo battery bank,,,,,,,,,,,

[kmacdonald]

Originally Posted by robert sailor

Lightning....the act of being completely unpredictable as to where/who it's going to strike, when it's going to strike and what damages it will create. Sorta the C19 of mother nature. I've read so much on the subject and learned so little it's almost embarrassing.

Well put. You cant do anything about it. It is what it is. Forget the snake oils.

[kmacdonald]

Originally Posted by fguptill

Walking around in Miami airport a few years ago I noticed that its buildings are equipped with hundreds of rooftop lightning rods. It seems likely that someone might have confirmed their utility before incurring such a large expense.

No. The contractor just knew the right people.

[Cpt Pat]

Originally Posted by Wallaby

Bonding and Grounding are crucial. With regard to surge protection: 12v 10kA on the primary electronics?



Do you have better suggestions for surge protection? I think that would be helpful.

1) I use TVS (transient voltage suppression) diodes across every power input to every load, as near the load as possible. Zener diodes work too, but the junctions saturate at lower currents. Here's an example diode for 12 volt buses: https://www.digikey.com/product-deta...ACT-ND/2770240. Those'll cost you 59 cents each.

2) All my antennas have surge suppressors. Here's an example list: https://www.dxengineering.com/search...torder=Default. Those suppressors should mount either to the mast base (if it's out of the weather) or to one of the ground straps described below.

3) I have a common ground point to which all grounds and shields terminate. This is to prevent ground-loops. Signal level wires (NMEA data, audio, control cables, etc.) are all shielded and connected to a negative bus at only one end. Again, to prevent ground-loops (this is a common practice in broadcasting). If the manufacturer didn't provide shielded wire (proving they're amateurs), I run the lead wires through shielded brain that I provide myself. Gutting coax cable is a good source.

4) All chainplates, the engine and the mast step are bonded together. If the entire boat jumps up 1 million volts, it doesn't matter provided there are no differences of potential. Otherwise, you'll get destructive "side-strikes."

5) The common "ground" (electrical drain to water) is at the backstay chainplate, providing a straight path from the masthead, down the backstay, to the water, with no sharp bends. I have a 3 square foot zinc plate that is trailed from the backstay when underway in lightning conditions. The plate is left in the water when the boat is docked. I recommend against rigidly mounting any plate to the hull - like a bronze "dynaplate" because: a) a hit could cause a steam explosion that will blow a hole in the hull and, 2) bronze will corrode my aluminum prop nearby.

6) The common ground fans out to the grounding (negative) buses with 1 inch-wide stainless flat braided conductors (from American Grounding Systems) run down the bilge. (Seawater dissolves copper wire.)

7) I have an industrial metal oxide semiconductor (MOV) across shore power, with a fast acting circuit breaker (which has tripped during thunder storms) to break shore power to the entire boat. Here's an example (for 120 VAC): https://www.digikey.com/product-deta...4089-ND/485303. Pricey yes, but you only need one, and destructive AC transients produced by inductive loads on the shore power are very common. Feel the MOV occasionally, and if it's warm, replace it. Put it in a metal AC utility box.

8) I do NOT carry the shore power safety ground through to the boat. Again, to prevent ground loop currents. The boat's safety ground is the common ground with the zinc plate.

Your VHF antenna at your masthead could still become a "sacrificial air terminal" for lightning. But with a good suppressor, the damage should stop there.

[PineyWoodsPete]

Originally Posted by Montanan

Well lets lighten up this thread.

OK! There was a "throw tent" we borrowed from a daughter that we stowed on the fated Sea Pearl's side shelf - you know, unfurl it and throw it up in the air, it (supposedly) floats down full erected.

She and hubby took it out west on a car camping trip. The first rainy night they slept in it they were drenched with water dripping in from countless lightning pinholes we/they hadn't seen, and slunk back into the overstuffed, steamy Subaru to complete the horrible night. I'd always suspected Rodney was dragging along some bad Karma!

[seabreez]

Originally Posted by robert sailor

By the way I notice you have a steel boat, you’ll have no problems.

Years ago our rescue vessel got hit by lightning during a storm... my wife saw the hit and woke me up. I never heard anything. Half asleep sitting on the edge of the bed, I looked outside and observed the fiberglass antenna on fire during the downpour, just like a candle on a birthday cake. I started to laugh and my wife was trying to wake me as she thought I was still sleeping. It was very funny. What do you want me to do HUNNNY!??? When it stopped raining, I went down to the boat and assured myself that the bilge pump was still operational. In the morning I went to check and replaced the antenna and the coax and all the fuses, radar, radio, gps and everything else was ok. The antenna was mounted on the stainless steel radar arch and bolted down on aluminum deck plated vessel. No other changes were done to the vessel...

[waterman46]

Originally Posted by Frankly

Lightning protection (somewhat of a misnomer) is to protect the crew from being injured/ killed and the yacht from being holed. Other than these two very important considerations all else is just BS. The only nearly foolproof technique to prevent a strike is to hide under overhead electrical transmission lines (I once did this crossing the Okeecheobee WW during a really nasty Florida thunderstorm).


Frankly

Safer under power lines? Sounds questionable.

If a lightning strike popped one of those wires off its insulator, I would not want to be there!

[Chotu]

Sitting in an open bay, the only boat. Lightning crashing down all around. Thinking hard about this thread. LOL

But there’s not much that can be done. Luck of the draw.