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Old 03-05-2021, 17:03   #76
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Re: So my boat lacks a lightning ground.

Perhaps better to treat the oven thing in the manner of Pascal's Wager. If it costs nothing to put your portable electronics in the oven, and it might do some good, then what is there to lose? Especially if you don't have access to anything likely to be better. That's not the same as relying on it as a sure way of protecting your gizmos.

After all, most of the risk management I've been involved with is not about magic silver bullets, but relies more on using appropriate incremental steps, each of which tilt the odds a little in your favour. In that context, sticking everything in the oven when lightning threatens has a place. OTOH, IMHO, so does maybe keeping a sextant, a windup watch, a set of paper charts and maintaining the ability to use them, for when the magic smoke does escape from the GPS.
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Old 03-05-2021, 17:20   #77
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Re: So my boat lacks a lightning ground.

Insurance companies won't cover the boat if a survey shows there aren't two hose clamps on every thru-hull --- But I've never seen a survey where there's a mention of the lightening ground.

Insurance companies want to know how many fenders you'll put out before a hurricane in your hurricane plan -- But I've never seen them ask if you put your electronics in the oven during a thunderstorm.

Pretty convincing evidence to me that none of this does any good in the real world.
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Old 03-05-2021, 19:04   #78
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Re: So my boat lacks a lightning ground.

The discussion has been going on for a long time.
Here is what James Cook reported after he entered the port of Batavia in 1770:
"About 9 oClock in the Evening we had much Rain with some very heavy Claps of Thunder, one of which carried away a Dutch India-man's Main Mast by the Deck ^and split it, the Mn Topmt & Topgt mast all to shivers. she had had a Iron spindle at the Main Topgallant Mast head which had first Attracted the firy matter ^Lightning. This Ship lay about two Cables lengths from us and we were struck with the Thunder at the same time and in all probabillity we should have shared the same fate as the Dutchman had it not been for the Electrical Chain which we had but just before got up this carr[i]ed the firy ^Lightning or Electrical matter over the side Clear of the Ship, the Shock was so great as to shake the whole ship very sencibly, this instance alone is sufficient to recommend these Chains to all ships whatever, and that of the Dutchman ought to caution people from this a having Iron spindles at their Masts heads ó"
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Old 03-05-2021, 21:37   #79
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Re: So my boat lacks a lightning ground.

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Originally Posted by Jhclay View Post
The discussion has been going on for a long time.
Here is what James Cook reported after he entered the port of Batavia in 1770:
"About 9 oClock in the Evening we had much Rain with some very heavy Claps of Thunder, one of which carried away a Dutch India-man's Main Mast by the Deck ^and split it, the Mn Topmt & Topgt mast all to shivers. she had had a Iron spindle at the Main Topgallant Mast head which had first Attracted the firy matter ^Lightning. This Ship lay about two Cables lengths from us and we were struck with the Thunder at the same time and in all probabillity we should have shared the same fate as the Dutchman had it not been for the Electrical Chain which we had but just before got up this carr[i]ed the firy ^Lightning or Electrical matter over the side Clear of the Ship, the Shock was so great as to shake the whole ship very sencibly, this instance alone is sufficient to recommend these Chains to all ships whatever, and that of the Dutchman ought to caution people from this a having Iron spindles at their Masts heads ó"
Yes, yes, but did he put his electronics in the oven and were they OK?
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Old 03-05-2021, 22:13   #80
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Re: So my boat lacks a lightning ground.

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Argument by aphorism, as usual, isn’t very effective. While doing something, anything, might be better than doing nothing, that isn’t always the case. Sometimes just doing something makes me feel better, without necessarily actually changing the course of the universe.

Some ovens can be quite effective as a faraday shield. Others are virtually useless. Putting your GPS in either might make you feel better. Is that the "good" that we should accept over the "perfect?"

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...

Quote:
It's commonly thought that a refrigerator or freezer can serve as an ersatz Faraday cage. But unless the seal is really tight, it's not likely to work. Likewise, a microwave oven also does not a Faraday cage make. A police precinct in Greenfield, Massachusetts, tried to prevent the remote wiping of phones it confiscated by placing them in microwave ovens. They found that only commercial-grade ovens worked.https://www.pcmag.com/how-to/how-to-...n-faraday-cage
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
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Old 03-05-2021, 22:55   #81
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Re: So my boat lacks a lightning ground.

Quote:
Originally Posted by CarlF View Post
Insurance companies won't cover the boat if a survey shows there aren't two hose clamps on every thru-hull --- But I've never seen a survey where there's a mention of the lightening ground.

Insurance companies want to know how many fenders you'll put out before a hurricane in your hurricane plan -- But I've never seen them ask if you put your electronics in the oven during a thunderstorm.

Pretty convincing evidence to me that none of this does any good in the real world.
Ins cos don't require a lot of things that good and sensible boaters should have.

BTW not all hoses need be double-clamped. Not even the AbyC code suggests that.
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Old 04-05-2021, 00:37   #82
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Re: So my boat lacks a lightning ground.

To sum up :
Get a grandma's Kellogg's metal box and save some money.

If alu mast - connect the mast with a thick copper or alu bar (well connected) going straight DOWN to the naked iron keel, or if you don't have that, down to a several feet long alu or copper ground plate fixed to the hull (in an always submerged area). No spikes on the plate, as the lightning current WILL find its way into the water. Spikes will attract all plastic bags in the ocean.
If wood mast - get 4 long chains. Raise them to the top of the mast, and hang them down over the bow, the stern, to starboard and to port side, respectably (hmm - probably not the easiest to do when under sail). Each must be 4-5 feet into the water.

Do not connect any ground (-) to the mast. It is not a bus bar.
Unplug your electronics.
Use a big old style Edison knife switch for the power for these devices (for both + and -). Shut down the devices and turn off the switch.

Wear earplugs. A thunderclap does not do any good for your hearing.

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.

Did I forget anything ?
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Old 04-05-2021, 06:14   #83
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lightning surge protectors

Does anyone use these:

https://www.dxengineering.com/search...rder=Ascending


https://www.gigaparts.com/mfj-270.html


or others?

EDIT ADDED A FEW MINUTES AFTER: and to what do you ground it?
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Old 04-05-2021, 06:21   #84
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Re: lightning surge protectors

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Yes, the Polyphasor on my VHF masthead antenna coax near the mast base.
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Old 04-05-2021, 07:37   #85
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Re: So my boat lacks a lightning ground.

Yes, the good lightning suppressors work. But you have to use a good one. Polyphaser and DX Engineering and Alpha are examples. There are lots of variations on the theme as to which model to choose. Some pass through DC on both the shield and the center conductor. Others will DC block one or both sides of the coax. The latter type help avoid the problem where the coax shield is connected to -12v at the radio and to the mast at the antenna. The biggest installation problem is finding a way to make the seawater connection at the base of the mast. If you donít do that, it will protect from high voltage between the center conductor and the shield, but not common-mode high voltage. I prefer the ones that have a replaceable gas tube as the protection element. You canít tell if the gas tube works and it might not if itís already sacrificed itself in a strike you didnít notice. So at about $10, I replace mine at the start of the rainy season.

Putting stuff in an over canít hurt. If nothing else, itís less likely to get wet, or lost or thrown on the floor. Maybe the oven will provide a little electrical protection or maybe not. Thereís no good reason NOT to do it. But thereís also little proof that the oven DOES, as opposed to maybe/might/could, actually protect the electronics.

A solid metal box with a tight fitting lid, like the ones that come with some cookies or crackers is a better choice than the oven. Mine came full of crackers.
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Old 04-05-2021, 07:50   #86
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Re: So my boat lacks a lightning ground.

We use Amo-cans (army surplus ammunition cans) when doing RFID tags work and we do not want the antennas to pickup the tags (same thing cats and dogs sometimes get but we do it on fish). The rubber seal should maybe be removed? Dirt Cheap. The faraday drybags never worked. But that is all RF not lighting.





(we also use them for the head on raft trips)
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Old 04-05-2021, 08:17   #87
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Re: So my boat lacks a lightning ground.

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Originally Posted by carstendenmark View Post

Put up a picture of Saint Barbara and start praying like h.ll.

Well, that's not ABYC code but sailors who have been caught in actual electrical storm have been known to pray like heck...


Srsly folks, all this cruising thing is supposed to be fun, why alll the dispute and argument?
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Old 04-05-2021, 08:28   #88
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Re: So my boat lacks a lightning ground.

The issue with clamps and suppressors is that they won't protect against the emp wave associa5ed with lightning that fries electronics. They only shut the current in the cable they're attached to, the emp wave passes through everything including the body of the electronic items themselves. Chartplotters etc are not shielded either so though they may even seem fine and unaffected at first, later on they may start acting up due to the emp damage. On commercial vessels, efforts are taken to shield the electronics themselves as well as the cabling.

Even electronic items that are turned off and physically disconnected from anything else can and often do get fried in a lightning strike so a suppressor would be irrelevant. Thats sort of why people resort to Faraday cages.
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Old 04-05-2021, 08:43   #89
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Re: So my boat lacks a lightning ground.

By the way wooden masts aren't any less lightning conductive than aluminum ones. Electricity travels on the surface, edges, and the material isn't important; height is what counts. Witness trees struck by lightning.
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Old 04-05-2021, 08:53   #90
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Re: So my boat lacks a lightning ground.

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Srsly folks, all this cruising thing is supposed to be fun, why alll the dispute and argument?

I agree with trying to keep this great forum friendly. I think we all do. It is such a golden asset. It is easy to read into other peoples witting as mean or offensive. I feel it is human nature when communication is not done in person or without body language. Lighting is not a settled topic so there surely will be disagreement and opinions and a lack of evidence on some or all of those opinions. I appreciate a diversity of perspectives even if they are in disagreement.

I have been reading a lot on lighting lately as I, like PatB (the OP), am sitting here staring at my mess of wires and plates and copper ribbon wondering how best to proceed.



Inspired by this discussion, last night I made a mess of my garage, pulling old boxes out of the attic. I was looking for an early edition Nigel Calder "boatowner's mechanical and electrical manual". I failed to find it. But I wanted to compare the lighting chapter in the early editoin with the new edition that i read this last summer. I recall it being very different, but... that was long ago. A great read on the topic, by the way, PatB.
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