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Old 04-05-2021, 08:58   #91
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Re: So my boat lacks a lightning ground.

Many professional guys here, with tons of experience from the professional world, it seems.
Many bright and en-lightened phd professors and EE engineers here on CF ! Great !

But, can any of you guys provide me a single link, how the pro's like ferries, fishing boats, oil rigs etc. protects themselves against lightning strikes ?
We do not hear "breaking news" of strike disasters from them at all.
They are stuffed with people and electronics when they set out.
No problem. Day after day. In severe weather conditions.
All their gear is far better than ours.

HOW DO THEY MANAGE STRIKES ?

So :
Are we just missing some important information ?


We should learn from the pro's
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Old 04-05-2021, 09:09   #92
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Re: So my boat lacks a lightning ground.

So I never thought this question would be controversial. Boy was I wrong.

Anyways between ABYC recommendation the fact that Nigel Calder* hasn't steered me wrong yet and similar statements by other people in the thread I am going to ground the mast and chainplates to a ground plate below the waterline.

At the very least I know how it is wired now is completely wrong. I disconnected the mast from the DC negative bus. Someone suggested the prior owner might have been using the mast as the DC return for instruments and lights and I agree that makes sense given the bizarre wiring but if they were at one time they weren't when I got her. I verified they have their own DC negative and everything works with the weird mast to DC negative bus connection removed.

Since only 1 in 1000 boats a year gets struck by lightning I figure it may not make much of a difference either way (connect mast to ground plate or leave mast ungrounded). The reality is most boats are just lucky and grounded, ungrounded, or wired horribly wrong like mine was they just avoided being in the wrong place at the wrong time.

* Author of "Boatowner's Mechanical and Electrical Manual"
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Old 04-05-2021, 09:34   #93
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Re: So my boat lacks a lightning ground.

Like I said in a previous post here :
Put up a picture of Saint Barbara and start praying like h.ll.
Or, leave it all to God, make yourself a cool drink and enjoy the fireworks.

If you do what you think is a good solution to keep you calm and safe, then do it !

We are all going to die, don't worry. Your day WILL come.
The exitement of life is - WHEN is the day !

However, when you're still alive, you'll need to replace your cellphones, chartplotter etc. every 5 or 10 years anyway.
Let the insurance pay ! Let nature do the work for you.
Many boat owners are actually quite happy to receive a huge payment after a little "toast" of the boat.
If you do all power and electronic cabling wrong, then the chance for a "Lucky Strike" that toasts your stuff well is much better.

I think that this is the philosophy of all those, who don't care much of lightning strikes to their boat. Live and let die.

Consider it - you may end up being quite happy (if you survive the hit) !
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Old 04-05-2021, 10:35   #94
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Re: So my boat lacks a lightning ground.

OP, as you have an alu mast with SS rig, I think that you can just make a grounding of the mast to a big aluminum ground plate, placed on one side of your keel. But, make it well and sturdy ! Square area of the pipe to be the same as the total square area of the mast profile.
Connections done well, face to face.
NO stainless steel washers between the conducting faces.
You CAN use SS bolts and washers.

Conductive paste may help, but do your homework well, then you can rely on good connections.
Link to paste :
https://www.amazon.com/MG-Chemicals-.../dp/B00SMRNSR0

The ultimate best solution (corrosion safe) is to use a pure alu bolt for connecting the down rod to the mast.
Link to alu bolt :
https://www.mcmaster.com/92722A122/
Be careful with the torque wrench...

So, a heavy alu pipe for connection (copper will do too, and can be half the square of alu, but be aware of galvanic corrosion), going straight down from the mast to the plate. The reason for going straight down is, that lightning (and currents in general) likes a direct path. Like a water pipe, without bends, it makes a free flow.

No need for your chain plates to be connected, if you make it like this.
Let the lightning make it's way easily.
The lightning will prefer to discharge through the very low resistance alu mast, rather then through the higher resistance of the thin SS stays and shrouds.
Again, only provided, if you make a good low resistance path for the lightning to get into the water all through the mast.


Put the VHF antenna on a spreader instead of the top of the mast.
Less vulnerable.
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Old 04-05-2021, 16:30   #95
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Re: So my boat lacks a lightning ground.

Quote:
Originally Posted by Cyrus Safdari View Post
But why take the risk in the first place?


The suggesti Isnt to do just ANY OLD THING rather to do whats rational and has the best science and facts behind it. Basic lightning protection neednt be elaborate or expensive. Considering all the bs and crap that boaters accumulate, and the very low cost of a tin box, or even a commercial emp resistant bag from Amazon, what explains this insistence on using the oven? Heck even a cocktail shaker can be used as a Faraday Cage. (I'm sue some expert will pop up now and say cocktail shakers are not effective but they're certainly more effective than an oven.)

The less penetrations the better the Faraday effect, this is simple and kids have made Faraday cages for generations. But if we want to ignore basic science asxwell as things like AByc recommendations re lightning etc, and instead rely on anecdotes about what happened to somebody's buddy instead...


This is the plan that went awry https://www.masslive.com/news/2014/0...n_to_micr.html


Pascals Wager assumes you have only 2 options: put your electronics in the oven, or don't and take the risk. Well, there is a probably more effective third alternative of making or buying a real Faraday Cage which is hardly any more expensive. So why rely on your oven, when you certainly don't have to? Unless you have some particular reason to want to only rely on the oven as a Faraday Cage? And so can't possibly spend the $5 it would take to line a tin box?

Honestly folks, I'm flabbergasted by the insistence that ovens make Faraday Cages. Is it so hard to say, eh, maybe not, why risk it? I mean,, it is an oven after all, and ovens are used for cooking food not intended nor designed to be used as a Faraday Cage..Does this really need explaining? Would you use you liferaft as a... toothbrush?

People just astound me. Yesterday some moron was explaining to me how wearing seatbelts can be more dangerous because it causes people to be more relaxed drivers. A grown adult....

Anyways for "not becoming part of the path of least resistance" by not installing lightning grounds, that's usually not how lightning works. If it was,, then boats without lightning protection wouldn't be hit but they are ( lightning protection doesn't prevent lightning, it ties to minimize the damage) First, electricity travels the path of least resistance but after it has tried every path open to it. And the path of least resistance, as any ungrounded boat struck by lightning shows, can be right thruogh the hull. Second, you can't "attract" or "repulse" lightning. Again, the idea of lightning protection is to minimize damage if hit not preventing a hit. The most effective electricity resistance comes from empty air, and yet lightning shoots through air no problem. So the even if we assume that your boats electrical resistance has something to do with it, it would never ever come close to the electrical resistance of 3 miles of empty air
My Pascal's wager comment was more in the context of what might be worth doing in the event of being caught with nothing more suitable available. Obviously, if wishing to rely on a Faraday cage and cruising in areas prone to lightning strikes, pre-preparation by obtaining a purpose made container, or properly sealed metal box would be far preferable.
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Old 04-05-2021, 18:55   #96
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Re: So my boat lacks a lightning ground.

Quote:
Originally Posted by Bycrick View Post
Some faraday cages are made of mesh. But the holes will in fact allow energy to pass through depending on the relation of the size of the holes to the wavelength of the energy. Since lightning has a frequency range of essentially DC to several hundred MHz, the holes have to be pretty small to block all the energy.

A microwave oven is designed to keep energy at 2450 MHz from getting out. That says absolutely nothing about letting energy from DC to 1000mHz from getting in.
1. The size of the hole must be small compared to the wavelength.

2. The wavelength increases as the frequency decreases.

3. Therefore, if a microwave contains 2.45GHz and lightening frequencies are less than 2.45GHz, the microwave should be effective against lightening.
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Old 07-05-2021, 22:15   #97
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Re: So my boat lacks a lightning ground.

OOOPS. I said PatB was the OP in a previous post, it was Statistical. Sorry. So many people.
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Old 07-05-2021, 22:31   #98
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Re: So my boat lacks a lightning ground.

Quote:
Originally Posted by coopec43 View Post
When I saw the following video clip it brought home to me that getting hit by lightning is the luck of the draw. According to the lightning map lightning is not a big problem mid ocean.
Ignore them if you have already seen them


https://www.blitzortung.org/en/live_lightning_maps.php






I was involved with the beta of the lighting interface for wildfire workers back when it was just a few sensors. I was told by one of the BLM or NOAA guys who pioneered lighting sensors/observations that "it does not work over the ocean" I tried to find this in peer review or grey literature the last couple days and I failed. But, i think the lighting sensors in the map to which you linked is perhaps not able to pick up mid ocean lighting unless very strong. Making it appear to rarely happen. Enchanting map none the less with plenty of scary storms over the Bahamas today.
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Old Yesterday, 03:56   #99
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Re: So my boat lacks a lightning ground.

Many factors contribute to the difference in weather, between land and sea, including, but not limited to, friction, moisture, and heat capacity [water has about four times higher heat capacity than land].

According to NOAA:
“... Lightning doesn’t strike the ocean as much as land, but when it does,it spreads out over the water, which acts as a conductor. It can hit boats that are nearby, and electrocute fish that are near the surface ...”
https://oceantoday.noaa.gov/lightning/

According to GlobalSailingWeather.com [Dr. A. Pessi*]:
“... Most of the lightning in the world occur over the land. In fact, it is estimated that nearly 90% of all the lightning strokes hit the land, although land covers only 30% of the earth's total surface area. However, some parts of the oceans are still relatively lightning-active ...
... Specifically the eastern and central parts of the Atlantic and Pacific Oceans near the ITCZ experience lots of lightning. Also the ocean areas east of the continents between about 30 and 50 latitude have lots of thunderstorms that have been often propagated from the continents and kept active over the relatively warm sea surface ...”
Thunderstorms and lightning

*Publications by Dr. A Pessie ➥ Publications and presentations - A. Pessi
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Old Today, 04:05   #100
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Re: So my boat lacks a lightning ground.

Unfortunately, the “super bolts” seem to target the ocean.

“More than 90 percent of lightning bolts strike over the continents, but the lightning that strikes the ocean can be far more intense. Rare “superbolts,” for example, with flashes 100 or 1,000 times brighter and more powerful than a regular bolt, are far more likely to hit the ocean. Exactly why this is so is still under debate.”

https://www.smithsonianmag.com/scien...ean-180976707/
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