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Old 10-08-2012, 12:52   #46
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Re: Lightning Strike Damage Details Needed

mrohr, if someone says lightning kills more people than anything else, and we already know one mudslide in central america can kill 200,000, one earthquake in China or Pakistan can kill 100-500,000...

Why question the claim? Obviously, there must have been over a half million deaths from lightning strikes last year. That would also explain why there are such incredibly high numbers of missing persons reports in the US every year, with no sign of the people reported missing. Just blown off the planet.

Ties everything up rather neatly, don't you think?

As for kraken research...I've been offering internships for years now, but after the last two interns got eaten, I'm afraid it has been hard finding good help. I warned them not to have sushi or sashimi in the cockpit, but no, you know college kids, they just wouldn't listen.
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Old 10-08-2012, 12:58   #47
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Quote:
Originally Posted by zeehag
colemj--i am not TELLING anyone to do a s i do--i am stating the OBVIOUS. EVERY SINGLE BOAT I KNOW OF PERSONALLY--AND YES I DO KNOW MANY boats PERSONALLY ---with alleged dissipators, have ATTRACTED lightning to them to the point of near total damage per insurance companies,,, one more than one time in 4 years. you do the math.

airplanes also go well to weather......
do airplanes fly in a salty oceanic environment????
Zee,

No one doubts your personal experience but personal experience is anecdotal evidence. It is not evidence that can be used to justify decisions. As a nurse I am sure you have heard your patients spout rubbish about new ages healing things and how it healed their friends but you, backed by medicine, knew it was a load of *****.

I'm not saying your position is *****, but even if you experienced 50 strikes it doesn't mean that your experience is fact since you can't know what exactly every boat did; for lightening protection, grounding philoshy, how they were grounded to the marina power, height of mast, material of hull, SSB connection, cables in mast, what equip,ent was on, etc....

There are so many damn variables to this problem, to say one knows how it works is crazy. Also to say that engineers are in collusion with the government to intentially cause damage by installing and recommending bad grounding techniques???

I have friends who are electrical engineers and you mention having relatives who are EE's as well. Have you spoken to them? They tend to not be the social type, but instead the locked into teh closet in the basement type who ate more interested in facts and design than they are in polotics and money.

My mates who are EE, if they tell me something I take it as gospel.
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Old 10-08-2012, 13:08   #48
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Re: Lightning Strike Damage Details Needed

Quote:
Originally Posted by mrohr View Post
Lightning is the #1 killer of all natural disasters on the planet. It is the fact that it is SO common, and kills one at the time, that has it off of the national news. This is as true on boats.
???????????????????????? M Johnson in the post above

Whoa! lighting kills more people than Floods? more than Earthquakes?more than Hurricanes?more than Volcanic eruptions? This truth is suppressed? You have come to this conclusion after reading hundreds of books?
Mr Woodward above post, states:"this make a lots of sense to me".

Haven't anybody here heard and done research on GIANT KRACKNEN!!!!
Hey mrohr, if you're going to quote me, quote me correctly. I said "Mark makes a lot of sense to me", referring to the manner in which he is bonding his boat to conduct the voltage to ground in a less destructive manner. I have no idea whether lightning is the no 1 killer, but so what? It kills a lot of people: 24,000 worldwide is the number that seems to be circulated. Your sarcastic response doesn't add to the main point of this thread, which is how to mitigate lightning damage to boats.
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Old 10-08-2012, 14:53   #49
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Re: Lightning Strike Damage Details Needed

How does a dissipator (bottle brush) work? Well, it has a thousand needle points, designed to work like 1000 lightning rods (which are always pointed, you may notice) in the theory that it will bleed off more of the ground charge, quickly.

Now what happens when you bleed off the ground charge into the air?

Instead of just sitting at ground, with ground?

Right, you've helped put up an ionized path into the air, and when that path gets into the clouds, it will bring down a cloud-to-ground return strike. So yes, in theory, any type of lightning rod or brush WILL attract lightning, if that ionic charge doesn't get spread around or dissipated before it gets upstairs.

I've never seen that aspect of it studied, but suspect it would be damned hard to measure the position and strength of a small "ionic cloud" during thunderstorms. Given a heavy rain or wind to disperse the charge, they might work. Given still humid air allowing it to build and stay cohesive, it just might not.

Meanwhile, someone has sold bottle brushes that are installed over EVERY traffic camera in Broward County and a chunk of other lightning infested places.
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Old 10-08-2012, 15:46   #50
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Re: Lightning Strike Damage Details Needed

I found this article quite informative:
Lightning And Sailboats
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Old 10-08-2012, 16:19   #51
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Re: Lightning Strike Damage Details Needed

Quote:
Originally Posted by hellosailor View Post
How does a dissipator (bottle brush) work? Well, it has a thousand needle points, designed to work like 1000 lightning rods (which are always pointed, you may notice) in the theory that it will bleed off more of the ground charge, quickly.

Now what happens when you bleed off the ground charge into the air?

Instead of just sitting at ground, with ground?

Right, you've helped put up an ionized path into the air, and when that path gets into the clouds, it will bring down a cloud-to-ground return strike. So yes, in theory, any type of lightning rod or brush WILL attract lightning,
In simple terms an ungrounded sailboat mast develops a static charge at the masthead. This charge makes the the mast ( slightly ) more likely to get hit by lightning.
When the boat is fitted with a propper lightning ground the masthead returns to ground potential which is why grounding slightly reduces the chance of a strike. The real purpose of grounding is not however to reduce the chance of a strike, but to more safely dissipate the energy of any strike that occurs reducing the damage.

Grounding is the most important saftey factor, but some boats go to the additional step of mounting a metal rod above any other masthead structures, such as VHF aerials, to try and protect those. A further refinement is to fit a masthead brush, the extra benifit of these is debatable and probably marginal. The important message is grounding will reduce the risk damage, particularly catastofic damage where the boat sinks or is dismasted. Contrary to common myths grounding will ( slightly) reduce the risk of a boat sustaining a strike.
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Old 10-08-2012, 16:28   #52
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Re: Lightning Strike Damage Details Needed

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Originally Posted by hellosailor View Post
... (which are always pointed, you may notice) ....
Actually, they aren't. Modern ones have a rounded tip.
Lightning Rods - Air Terminals - Lightning Rod Parts

There's some good info on mast protection here
Four Mast Failures
A pic from the article
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Old 10-08-2012, 16:45   #53
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Re: Lightning Strike Damage Details Needed

Quote:
Originally Posted by hellosailor View Post
How does a dissipator (bottle brush) work? Well, it has a thousand needle points, designed to work like 1000 lightning rods (which are always pointed, you may notice) in the theory that it will bleed off more of the ground charge, quickly...
Dissipators Don't work, and Blunt/Rounded Rod tips work better than Sharp Rods.

Excerpted from “
“A critical review of non-conventional approaches to lightning protection”
M. A. Uman, V. Rakov - Bulletin of the American Meteorological Society
“... SUMMARY. The conventional lightning protection technique has proven its effectiveness as evidenced by the comparative statistics of lightning damage to protected and unprotected structures ...
... Lightning elimination systems cannot prevent the initiation of lightning in the thundercloud and are unlikely to be able to avert an imminent lightning strike ...”
http://www.lightningsafety.com/nlsi_lhm/Uman_Rakov.pdf

Excerpted from:
“NON CONVENTIONAL LIGHTNING PROTECTION SYSTEMS”
Vernon Cooray - Uppsala University, Uppsala, Sweden
“...Both theory and experimental evidence show that Early Streamer Emission (ESE) principle does not work under natural field conditions and that there is no justification at present to assume that the ESE rods perform better than Franklin rods ...”

http://www.iclp-centre.org/pdf/Invit...ooray-2010.pdf

Excerpted from:Experimental Validation of Conventional and Non-Conventional Lightning Protection Systems William Rison, Member, IEEE
“... Field studies of Charge Transfer Systems show that they do not prevent lightning strikes as has been claimed.
http://earthing.co.kr/PGS_forum/files/ieee_panel.pdf

Lightning Rods with Rounded Tips are preferred to Sharp Tipped Rods:
http://earthing.co.kr/PGS_forum/files/ieee_panel.pdf
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Old 10-08-2012, 17:22   #54
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Re: Lightning Strike Damage Details Needed

The plot thickens...
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Old 10-08-2012, 19:33   #55
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Re: Lightning Strike Damage Details Needed

There you go again Gord, muddying the waters with facts!
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Old 11-08-2012, 01:25   #56
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Re: Lightning Strike Damage Details Needed

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Originally Posted by colemj View Post
OK, you win. I just don't have the mis-wired logic circuits necessary to continue this debate with you - particularly since your expertise in all things is derived from your genetic similarity to highly educated people. Can't top that.

"if all you can see is pure science, you are missing out on reality." Couldn't compete with this if I wanted to. I admit it - I am challenged when it comes to having unsupported beliefs and opinions slavishly held against all evidence. I bow to your ability here.

To complete the capitulation, I will end this with this advice to anyone coming across this thread in the future seeking information on this topic: Read zeehag's posts on this topic. Search for more of her posts on other topics and read those. You will understand her expertise.

Mark
+1 on this comment

The problem on these forums is that its so easy to make out that you are some sort of authority on various subjects when you might not be.

I guess its a desire some people have to appear more intelligent or more experienced or more important etc etc.

This, coupled with the forum concept, makes a very dangerous combination.

It is often very difficult for other members to see this, which often leads to very dangerous or misleading advice being given.
This advice unfortunately is then taken on board by other forum members non the wiser.
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Old 11-08-2012, 10:11   #57
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Re: Lightning Strike Damage Details Needed

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Originally Posted by Jerry Woodward View Post
Mark makes a lot of sense to me. I would also think that surge suppressors would help lesson the chance of electronics getting fried. You can get surge suppressors for the 12V lines as well as coax and other cables. Does anyone use these? What about hooking up surge suppressors to all the switches in the electrical panel? My (limited) understanding is that these work by diverting a high voltage current to ground. If you put a bunch of these on all your devices at the panel, then you could run all the grounding wires to a large copper wire going to ground as in Mark's setup.
Yes you have the correct way to deal with destruction of electronic equipment. Following are links to items I found on the internet. How to use these items are at a link I posted previously Lightning Protection

Two amp circuit lightning protectors, 18 volt turn on for smaller 12 volt DC items like GPS, liquid crystal display depth sounder.
PolyPhaser 12 V Surge protector

12 Volt DC, 30 amp power supply surge suppressor with negative ground, 18 volt turn on with 18,000 amps diversion to ground. Use this for transmitting with SSB, or VHF.
PolyPhaser 12 Vdc, 30 A surge suppressor with negative ground

DC blocking lightning protectors for coax antenna cable
Industrial Communication Engineers, LTD.

You also will need a protector for 120 volts for connection to dock side power.
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Old 11-08-2012, 10:46   #58
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Re: Lightning Strike Damage Details Needed

Paul, if round tips serve a purpose either someone doesn't want to get poked in the eye or someone has thrown out an awful lot of "established" theory to make that change. Damfino.

Jerry, surge surpressors might protect you from starting motor surges (600V) or line power surges (10,000V) and that's good if there's just some inductive surge in the power lines on your boat. But of course, if an actual strike gets into the wiring...millions of volts and the surge protector will be part of the same smoke cloud that the former instruments turn into.

You'd need something like a Polyphaser, with a dedicated ground line, to protect anything. They're a bit pricey but worthwhile in an antenna cable or other area of prime concern. (Or, of course, you can follow the old practice of simply keeping your antenna cable plugged directly into a ground when the radio has been secured, or lightning is in the area.)
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Old 11-08-2012, 12:14   #59
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Re: Lightning Strike Damage Details Needed

Quote:
Originally Posted by hellosailor View Post
Paul, if round tips serve a purpose either someone doesn't want to get poked in the eye or someone has thrown out an awful lot of "established" theory to make that change. Damfino.
....
Quote:
Fig. 1. Dragon Fly Plus' mast out of the boat. Note the lightning arrestor in the foreground, with a rounded end, which is the current best design
From the article on masts that I linked to above. The rod on my boat is also rounded. Not sure what the differnce in practice is between a rounded vs more sharp one is. I wouldn't think it is that significant being that the diameter of both is small and the voltages are way big.
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Old 11-08-2012, 13:18   #60
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Re: Lightning Strike Damage Details Needed

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From the article on masts that I linked to above. The rod on my boat is also rounded. Not sure what the differnce in practice is between a rounded vs more sharp one is. I wouldn't think it is that significant being that the diameter of both is small and the voltages are way big.
HelloS
You got me thinking about this, so I asked my friend Google. She came up with this explanation
Quote:
Typical recommendations suggest that the top-most end of the air terminal should be sharply pointed. However recent research by Professor Charles Moore suggests that in the event of a strike, a rounded end on the air terminal will intercept the lightning more effectively than a sharp spike, with the ideal radius of curvature being between 3/16 and 1/2 inch (5 to 12 mm). For the air terminal, a 1/2 inch or 5/8 inch (12 mm to 16mm) rod is recommended rather than a thin "antenna" sized air terminal which doesn't have sufficient sectional area to survive a strike.
from Lightning Attenuation Onboard
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