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Wallaby · 03-07-2020, 11:00

Quote:

Originally Posted by belizesailor

I have some AGM batterys ashore which the specs say have an "unlimited" charge absorption rate. When its time to retire them, Im going to hook a lightening rod to them and test that spec!

All I can say is that my boat was hit by lightning, and the brand new (1 day old) AGM batteries were zeroed. Nothing. They were taken to an auto-electrician to test. All five failed his test. I called Lifeline and they put a technician on the line with the auto-electrician. They talked (beyond my understanding) and performed test #2. The technician told me my batteries were like new, just charge them up and they'd be fine. He was 100% right.

He also said, I could toss the batteries in the water and zap them that way, but to dry them off before recharging. I haven't tested that. However, I have used Lifeline batteries every since.

barnakiel · 03-07-2020, 11:46

We sailed directly under major electrical storms a couple of times.

Never hit once. Boat grp, No lightning ground mounted.

Our friends were sailing under some heavy clouds and then ZAAAAAAAAP and here comes the weasel. Some damage to equipment on board, notably the stuff on the mast (wind sensor, vhf, ais, LED nav lights, etc. Alloy boat.

I am very very scared of electrical storms but from all I have read and heard, there is nothing that can be done (except to decide if you are in the grounding or isolating team).

I noticed that when our VHF radio is tuned up loud and attenuation is tuned close to the minimum, then any electrical bolts in vicinity will cause a short noise on the speaker. I believe this is in the range of maybe 25 miles or so.

barnakiel

Wallaby · 03-07-2020, 12:11

Quote:

Originally Posted by barnakiel

.

Our friends were sailing under some heavy clouds and then ZAAAAAAAAP and here comes the weasel. Some damage to equipment on board, notably the stuff on the mast (wind sensor, vhf, ais, LED nav lights, etc. Alloy boat.

barnakiel

I expect the alloy boat is acting as a large Faraday cage, keeping the EM radiation away from the goodies inside. Things at the helm (on deck) might not be protected. Things on the mast may get fried--vhf antenna is usually the highest so it gets whacked. Travels down the coax and into your radio. Possibly from there via DSC connections to other devices.

Frankly · 03-07-2020, 12:30

Might make more sense to think of "lightning protection" as two different but related issues.

A- Protecting the craft and it's crew from serious or fatal injury. This is typically done by providing a low impedance path from the masthead to the ocean. Lot of different schemes for going about this, pay your money and take your chances. For those that think this is a lost cause, I would direct you to shore based systems that safely conduct thousands of strikes to ground world over. The boat issue is actually simpler because most already come equipped with the lightning rod of superior conductivity. The issue is getting from the mast to the water and sea water is a far better conductor than most dirt.

B- Protecting the ships electrical system and the electronics most are equipped with. Here the solutions are much more problematic, but enough money will always provide a repair (not necessarily so with A). Lightning can range from light direct 10,000 amp strikes to 200,000 amps (mom ain't never going sailing again) shots. Also included in this are nearby strikes (emf field induction), and everybody in the marina plugged into shore power. Surge supressors (varistor, surge protection diodes, gas discharge tubes, switching arrangements, and grounding/ bonding configurations) can all help mitigate some of category B, but no gurantees. Again you pay your money and take your chances.

For the record Cbreeze is equipped with one or more of all the above. I have enough confidence in her set up that I operate my second favorite lady uninsured and live in Florida. "You pays your money and take your chances".

Slow Friday, Frankly

robert sailor · 03-07-2020, 14:27

I've been hanging around sailors and sailboats for longer than I can remember and we have discussed this topic a lot....I've gotten lots of advice from electrical engineers and I have in the past tried different ways to deal with it.
A friend was all decked out with his view of lightning protection which included huge cables from the base of his mast to the keel and in line suppressors and a bunch of stuff I couldn't even understand. He was hit years later and shortly thereafter his bilges started to fill up and when it passed his floorboards was when he noticed. Turns out there were small holes through his hull all around the boat at the waterline and fortunately he was close to a marina and got an emergency lift out once they put large pumps aboard to get rid of most of the water.
Later he told me he lost his alternator and most of his electronics but not all of them and he had no idea of why.
I've heard so many stories from sailors who were hit and everything from a little damage to alot that I don't believe anyone has a good answer.
If someone had it all figured out the insurance companies would be discounting their policies for those individuals.
I'm a skeptic by nature but I don't believe that anyone has it all figured out.
Fortunately almost no one is ever is killed from lightning on a sailboat boat strike.

Here's one piece of advice I can give you that works. If your boat is hit by lightning do not try to settle early with an insurance company, they want to and you shouldn't because I've been aware of problems that occurred months later that was related to a lightning strike and that is not uncommon.

flyingfin · 03-07-2020, 15:05

Apparently prayer works as well as any other device that is available on the market.

robert sailor · 03-07-2020, 15:14

Quote:

Originally Posted by flyingfin

Apparently prayer works as well as any other device that is available on the market.

That well, really? That's amazing!

Pegu Club · 03-07-2020, 17:49

Quote:

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.

Yes, we learned not to fly a kite in an electric storm

We to include you, have also learned that a boat bonded etc as you recommend can suffer a lightning strike and have all its electric equipment fried, and there is no way of stopping said lightning strike from happening, We can disagree but we don’t have to be disagreeable. 17th century cough cough...

Fair winds,

belizesailor · 03-07-2020, 18:18

Quote:

Originally Posted by belizesailor

There are a lot of scientists who have done research on lightening...and none of them seem to agree yet. [emoji849]

I did listen to the full podcast today, geez its long, cliff notes would have been preferable...could have summed it up in a few paragraphs, but it is very interesting. A worthwhile listen I think.

Jeff Thayer comes across as knowledgeable and credible. He is not hawking yet another miracle lightning protection system...which helps.

My initial response was based upon the fact that posts from lightning "experts" are made here pretty often and they are often contradictory.

Cpt Pat · 03-07-2020, 20:02

Quote:

Originally Posted by Frankly

(...)

Also included in this are nearby strikes (emf field induction), and everybody in the marina plugged into shore power.

That's a very important point! Induced fields and surges conveyed by shore power.

Your boat doesn't have to take a direct hit to be damaged. A vertical lightning strike can be viewed as the "primary" in an air-core transformer. Your vertical mast can act as the "secondary." The electrical current in the strike can magnetically couple to your mast and induce a large surge in your mast. The intensity of that surge will follow square-law: double the distance and the current is reduced by a factor of four, but it can still do damage. Protection is the same as for a direct strike.

I took a storage-scope (peak reading, display storing oscilloscope) out to the harbor and monitored spikes on the shore power one weekend. I saw spikes of several microseconds at 900 volts on the 120V mains. And that was during calm weather. When the power is daisy-chained to multiple outlets down a long dock and far from a transformer (transformers block the really intense short-period spikes), the health and quality of your neighbors' battery chargers and other gear affects you.

Freezer compressors on fishing boats are especially notorious for generating spikes. So surge suppression becomes an every day necessity in some places. Surge suppressors with robust metal oxide varistors (MOVs) - not the wimpy little things found in power strips - can clamp off those spikes. People with auto-transformers (isolation transformers) will get some surge-suppression benefit from those transformers too. If you have one, I'd install MOVs on the load side - not the supply side, to take advantage of the transformer core saturating and thus limiting a surge. It may ruin your transformer, but those are cheaper than everything else in your boat if a surge slips through.

If a surge doesn't hit you from the sky, it can still crawl up your shore power cord.

barnakiel · 04-07-2020, 08:18

Now to me the ever returning question is what if we think about the same boat in one of two states : grounded vs. un-grounded.

The grounded one will provide the better path, hence it may get hit while the ungrounded one provides no such a path and may not get hit.

So there is this argument against grounding.

A counter argument is when the un-grounded boat does get hit ...

b.

Pegu Club · 04-07-2020, 09:52

Five pages of stories, and a couple of theories on how to deal with lightning strikes, none of which are proven to work all the time. I suspect we would all agree that with the randomness and power of lightning one cannot predict the outcome of a lightning strike on a sailboat.

Fair winds,

Frankly · 04-07-2020, 09:59

I don't think you will find anybody that has some understanding of all this would support the idea that a well grounded mast is more likely to be struck.

I have a single data point to add to this. Some 10 years back just after retiring I was literally thrown from the bed by a lightning strike just outside out bedroom. At the time I had a 30' Hunter and my 32' IP docked approximately 75' from my bedroom. The Hunter had 49' mast and the IP a 45'. I looked out the bedroom window into one of them all Hell breaking loose Florida thunderstorms to see which one might have been hit. No fire and no sinking so I went back to bed. Both of these boats were equipped with 1 sq ft copper ground plates and redundant heavy connecting cables. Next morning I went to check the damage. Both boats were plugged into the same shore power duplex receptacle, both equipped with Freedom 10 inverters/ chargers keeping similar banks of GC2 batteries on float. The I/C on the Hunter was still charging the bateries, but the Radar would not come on. The I/C on the IP was smoked to the point I could smell it when I stepped below. Both still still working VHFs, instruments, HF radios, FM radios, TV, and autopilots. No other signs of damage. The still functioning VHFs (mast top whips) convinced me that the boats had not received a direct hit, but what.

Couple of years later a section of a live oak tree just outside our bedroom started dying. Tree trimmers removed dead section said lightning. That tree could not have been more than 5 ft taller than Hunter mast, and 40 ft away. Go figure. Hurricane Michael took care of the Hunter and the oak tree. IP still sailing today with all the same electronics (except inverter charger).

Frankly