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Old 09-07-2008, 19:28   #1
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No Bonding System

I have just purchased a 1979 Whitby 42. During the survey it was discovered that the boat has no bonding system in place. I am concerned about lightning protection. So far it seems that there is nothing that will "protect" you from lightning but surely there are ways to improve your chances of not being hit or surviving a hit by lightning. It looks like I have a clean slate here so I am looking for suggestions as to what to do. In looking at the boat it doesn't seem possible to get to all the areas that should be tied into a bonding system now, but what should I do? All help will be appreciated.
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Old 09-07-2008, 19:50   #2
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I am concerned about lightning protection. So far it seems that there is nothing that will "protect" you from lightning but surely there are ways to improve your chances of not being hit or surviving a hit by lightning.
I would say you don't want to improve your chances of being hit. The best thing is to not be plugged into shore power. Strikes by induction are far more common. The induction of the ground wire will do a fair amount of damage. Induction is when you don't get hit directly but something close does. This is one of those near miss can damage you a whole lot.

There is an infinite number of alternatives to lightning protection but I can't say I ever saw anything worth much. If you worry about it a lot then it does not decrease you chances. Moving away from FL is about 10 times better than anything else you can do. FL has 10 times more lightning than any place else in the US. Installing an owl on a pylon is about as good as many of the home grown solutions you can read about.

Seriously, don't leave your boat plugged into shore power is number one far and away from all else. Everything else costs a lot of money with an unconfirmed pay off.
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Old 09-07-2008, 20:14   #3
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There are a number of threads here covering lightning. You might want to search some of them.

Bottom line is that lightning may hit your boat. The most likely place to strike is the mast. Once the energy goes in it has to get out. The energy will follow the least resistant path to ground. Provide a solid clean connection to your steel keel if you have one and the energy will likely exit through the keel. If not it could exit through the hull and make a hole.

As the energy passes through your boat it will creat lots of havoc. It will blow stuff off the top of the mast and the energy pulse will blow most electronics that are hooked up to the boat and maybe the EMP will blow some that are disconnected.

A farraday cage is reputed to be the best protection for the equipment. Sticking portable devices in the oven is a touted strategy as the oven acts as a faraday cage. There are studies being done that you can google regarding creating a "network" of metal frames to effectively turn the entire hull into a faraday cage.

IMO the results are not yet conclusive as to the effectiveness of this.

We penetrate maybe 1-2 thunderstorms a month in our little boat. We have had lightning strikes near us but not hit us. We have had several boats struck on our moorings and last year one was holed and sunk.

I am in steep learning mode and maybe a bit of an idiot. I like to search out thunderstorms and bigger seas. I look at this as practice for my future - I like navigating in low vis, managing the winds and gusts and generally practicing boat skills. In a perverted way I would like to be struck by lightning to put the experience in my kit bag. But so far no "luck" - LOL.
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Old 09-07-2008, 20:36   #4
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While it IS true that nothing you can do is going to provide complete protection from lightening damage, the suggestion that Pblais makes that nothing helps is simply not true. A good grounding and bonding system CAN make a small but significant difference in damage from a lightning strike and that is not just me saying it but it is supported by good scientific data. http://www.thomson.ece.ufl.edu/lightning/IEEE.pdf

Now, WHAT needs to be bonded, and how is a matter of discussion. Don't forget that bonding underwater metals can cause corrosion problems that need to be addressed.

A minimum system would have the mast, shrouds, stays and chainplates all grounded with heavy gauge copper wire to the keelbolts of an external metal keel. Anything beyond that is "better" but how much better is a difficult question to answer. Despite that you will have many people give you answers with various levels of logic and technical sophistication behind them, but no real data.

It is not a simple issue, but to suggest that doing nothing is as good as anything else is irresponsible.
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Old 09-07-2008, 20:57   #5
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Did you know that men are four times more likely to get struck by lightning than are women? At anywhere from 10million to 120 million volts, I'm with Paul, I'm just not convinced. An ounce of prevention can't hurt I just doubt it's help. Protecting masts, shrouds, etc with ground wire is like protecting a nuclear power plant with a five amp fuse.
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Old 09-07-2008, 21:12   #6
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Lightning isn't one type of thing that strikes the same every time. The varieties and situations cover a very wide range. Doing something in FL is 10 times more effective than any place eles in the US since they get so much of it.

A good bonding sytem has more bensfits than lightning protection so I won't accept the idea as nothing helps. Bonding goes beyod lightning protection yet adds to the protection. The other areas it helps I think make a better case for it than lightning alone does. many issues aboard involve more than one issue.

On a direct strike you can be trashed pretty bad no matter what you do. There is not total protection strategy you can justify and pay for. Most damage is not from direct strikes however bad they might be. So where are the percentages to value. There are many risks and lightning is one of them and very poorly quanitified I believe. There are probably better avoidance strategies that you could invest in and get a better payback with than lightning.
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Old 09-07-2008, 21:12   #7
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Did you know that men are four times more likely to get struck by lightning than are women? At anywhere from 10million to 120 million volts, I'm with Paul, I'm just not convinced. An ounce of prevention can't hurt I just doubt it's help. Protecting masts, shrouds, etc with ground wire is like protecting a nuclear power plant with a five amp fuse.
It seems intuitive if the energy enters the boat, it has to get out.

The most likely place - and the only place I have heard of - for lightning to enter is the top of the mast. Letting it get to the water with minimal resistance has to help.

The shrouds and everything metal that is connected to the mast are already bonded to each other. You just need a path to the water. If the least resistant path is through a fiberglass hull you might get a hole

On its way through the lightning will wreak its havoc on the electronics.
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Old 09-07-2008, 23:04   #8
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It's true lightining seeks a path and can burn holes through just about anything and Paul is right in saying most damage is not from a direct hit. I should have been more clear. I was refering to a direct hit. I was a commercial electrician (not a marine electrician)here in Florida for a long time and repaired enough heavy equipment damage due to direct strikes. We've replaced melted and fried copper cables and connectors that could carry 500 times the juice any aluminum mast and a dozen shrouds could ever carry. It's just my opinion and I'm all for any protection people would like to take comfort in. I wonder if there has been ever a study in South Florida as to how many boats a year take a direct hit as compared to the thousands and thousands of boats that call S Fl. home that never get hit, ever. The odds have to be very very small.

I know. If you're that guy that does suffer a hit it ain't small at all.
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Old 10-07-2008, 00:14   #9
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The same person who did the research for the link referenced from UFL above founded a company selling a lightning protection system.

Marine Lightning Protection Inc.

Don't know if his system has been around long enough to have a track record to show if it's any better than anything else.

John
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Old 10-07-2008, 01:37   #10
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Just to add to the mix of opinions; I want to clear up a common misconception I often read on "lightning threads".
It is often stated that the lightning will travel to ground by the "path of least resistance" inferring that it will ONLY travel that path.
IMO, this is wrong, once the lightning has entered the boat (say by way of the masthead); it will travel along EVERY path to the area of opposite charge (i.e the water) and the current will be inversely proportional to the resistance of the path.

In general electrical terms, we consider the path of less resistance as the only critical path but when considering the value of current in a strike, we must consider all paths.

Put another way, if there are 2 possible paths; one of which is 100 times the resistance of the other, then 99% of the current will be in the path of the lower resistance and 1% will be in the path of higher resistance. However the big but is: 1% of a zillion amps is still a very big number and must be taken into account when considering lightning mitagation.
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Old 10-07-2008, 07:26   #11
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Good point. Having looked at the results of 4 lightning strikes this year, only one of which resulted in holing, the holed boat was the only one that did not have the mast bonded to the keel.

The 3 holes in the boat were all within 18 inches of the mast foot and the point at which the strike left the mast was clearly visible. It is possible that the honeycome of the cored hull (J24) was saturated and the moisture boiled/expanded but it didn't really look like that.

I thought I had a picture of the holes but they seem to have gone astray. If anyone is interested I will try and dig some more up this weekend.

It's interesting or that there were 3 other J24s in this row and our boat was 200 meters away. I think it's just bad luck.
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Old 10-07-2008, 08:42   #12
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We took a side hit a couple of years ago, lost the thermistor in the through hull was all. The brand spankin new 40.7 Bene in front of us took a direct hit and was heavily damaged. Our spar is 30 foot taller................... go figure.
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Old 10-07-2008, 12:00   #13
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Bonding systems are there more for preventing galvanic corrosion from dissimilar metals in your boat. If you have different fittings that make electrical contact via the salt water outside the hull, they form a battery circuit and then they destroy each other. The purpose of bonding is to keep them all at the same electrical potential (aka "voltage" level) so no circuit forms through the water, and no damage happens.

Some folks say very specifically NOT to use bonding, that it can create more problems than it solves.

Either way--bonding isn't the same as lightning protection. For that, you need substantial GROUNDING, typically by running battery cables or similar heavy straight metal paths from the mast down to the keel bolts (if there's an external keel) or other external ground plate, so the blast has a better reason to go straight out the bottom of the boat without flashing around sideways to other places.

You'll find a number of often contradictory articles about both grounding and bonding on the web. Read up, decide what you believe, and then make the changes that make sense to you. Or, make the changes your surveyor and insurer recommend and accept that as being a paid professional opinion and "good enough".
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Old 10-07-2008, 15:13   #14
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Thanks to everyone who has replied. Let me ask you all what you think of this suggestion that I received from another source ( a broker ) He claims that he simply attaches a heavey cable or chain to his backstay and puts the cable/chain overboard as a "path of least resistance". It seems to make sense to me but then I have to admit that I still think of electricity as magic and don't know zip about it. Any thoughts?
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Old 10-07-2008, 16:29   #15
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You mean, he puts a battery cable from the backstay into the water for lightning protection?

There are some authors that have discussed it. On the one hand, anything is better than nothing. On the other, they point out that you'd need bulldog (cable) clamps to make a good contact between the two, running them parallel for a while. Not just using a welding clamp, which creates a right angle. Lightning doesn't always follow right angles, sometimes it jumps past them. And, depending on how it is attached and how things arc at the masthead, the blast might come down the backstay, or shrouds, OR just come down the mast anyway.

Anything is better than nothing, but I'd still spend a little more than ten or twenty bucks trying to make Real Damn Sure the lightning had a nice attractive path straight down and out. When you're trying to find a safe place in the cabin (away from all the metal) during a lightning storm, all of a sudden you realize it's a tiny tiny cabin and lightning can make MUCH bigger jumps much faster than you can.

Aetheists in a foxhole, and all that good stuff?
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