Is Lightning Protection worthwhile?

[fredrussell]

... Huge cable sizes

It’s hard to imagine that any cable size would suffice really. Google seems to suggest lightning strikes range from 10 million volts to upwards of 100 million volts, and tens of thousands of amps. I’m surprised masts or bonding cables don’t just melt when subjected to that.

 

[geem]

It’s hard to imagine that any cable size would suffice really. Google seems to suggest lightning strikes range from 10 million volts to upwards of 100 million volts, and tens of thousands of amps. I’m surprised masts or bonding cables don’t just melt when subjected to that.

The cables on my friend's boat were like large welding cable and there were lots of them. I think the idea is that current has several paths to dissipate to the surface of the sea rather than going down one cable.

 

[Buck Turgidson]

Had at least a dozen lighting strikes in aircraft. 3 on one flight!! Aluminium aircraft are bonded to ensure the skin acts as a faraday cage. GRP structures have a copper web embedded just below the outer surface to achieve the same. Damage is usually a surface burn where it strikes and a Christmas tree pattern of burns where it leaves. They can be punctures but not always.

On our new A220s we had a couple of strikes in the first year that caused damage on many panels as it turned out they weren't all bonded correctly so the fleet got inspected and fixed.

The cage does a great job of protecting the contents and only once did we have instrument failures, that was the 3 strike flight (Nimrod low level over the Atlantic). The boys down the back claimed a lighting ball rolled through the cabin!

 

[coopec]

PROTECTING YOUR VESSEL

The most up-to-date research has confirmed that installing a grounding system is the best way to protect a vessel. The grounding system, which must be designed to provide a very low resistance path to ground (see Figure 1), is made up of a number of components: an air terminal, a down conductor and an external grounding plate.

When lightning strikes

 

[franksingleton]

On the basis of personal experience, I recommend fitting a Lightningmasrer. See

Obviously, I cannot be sur that it always works. I am 99% sure it saved us on one occasion. It just bolts/rivets to the mast higher than anything else.
Lightning protection is just as necessary for coastal sailing as ocean going. You can get hit in harbour even with other boats around you. For around GBP100 why not?
PS. I gorgot to say thst the mast should be connected to a good earth, eg a sacrificial anode. Basics,,y, it prevents s build up of charge at the mast head and so prevents strikes happening rather than dealing with a strike,

 

[Deleted member 478]

On the basis of personal experience, I recommend fitting a Lightningmasrer. See the top of our mast http://weather.mailasail.com/w/uplo...ail.com/w/uploads/Franks-Weather/anhinga2.jpg.
Obviously, I cannot be sur that it always works. I am 99% sure it saved us on one occasion. It just bolts/rivets to the mast higher than anything else. It require no power and is cheap.
Lightning protection is just as necessary for coastal sailing as ocean going. You can get hit in harbour even with other boats around you. For around GBP100 why not?

Link doesn't work.

 

[franksingleton]

Link doesn't work.

I am having more than my usual finger trouble. Does it now work? I cannot Ediror the, page mow,

 

[geem]

On the basis of personal experience, I recommend fitting a Lightningmasrer. See

Obviously, I cannot be sur that it always works. I am 99% sure it saved us on one occasion. It just bolts/rivets to the mast higher than anything else.
Lightning protection is just as necessary for coastal sailing as ocean going. You can get hit in harbour even with other boats around you. For around GBP100 why not?
PS. I gorgot to say thst the mast should be connected to a good earth, eg a sacrificial anode. Basics,,y, it prevents s build up of charge at the mast head and so prevents strikes happening rather than dealing with a strike,

Friends are ours we're in Mexico in a 56ft cat with carbon mast no lighting protection installation. The marina was full of yachts with masts. A big lightning storm went through. The only boat hit in the marina was a motorboat. No mast. Close to the water. Our friends were 4 boats away. How does that work?

We went through a very nasty lightning storm motoring between Bonaire and Grenada. We were in the lightning for several hours. Very nerve wracking. Lightning all around us. Some horizontal lightning going over us. No strike. We were in Florida at anchor in West Palm Beach. A nasty lightning storm went over us. A very close strike to the surface of the water next to us. Electronics went mad. I had the wind instrument and depth guage on. Very odd reading whilst the lightning was going on. Mast head led light and deck lights taken out. No other damage.
My point is that getting struck doesn't seem to follow any pattern. You can insist that you have a lightning protection system saving the boat but who knows. We don't have one but we have never had a direct hit under conditions I was convinced we would get hit being the only pair of mast for miles about in open sea. I think if you sail in places like Panama or Florida the risks are far higher than the UK. A huge percentage of boats that spend the summer in Panama have had lightning strikes. Probably not worth the effort in the UK

 

[ean_p]

This is the short article that came out of my research. Limited by the space available, not by the absence of information!
Interesting that the final paragraph seems to debunk the widely held belief that hanging chain from the shrouds will help to lead the current into the sea. It seems it may do exactly the opposite.

A surprising amount of research has been carried out into lightning strikes on yachts and boats, much of it in Florida but some in New Zealand, Australia and other countries. The findings are somewhat confusing when it comes to the layout of protection.

Detailed explanations can be found at
NASD - Boating- Lightning Protection, Lightning-Proof Your Boat and When lightning strikes
although there are many others.

To summarise, the optimum protection according to all authorities is provided by a heavy conductor, preferably copper of at least 21 sq.mm. running from 15 cm above the masthead and all antennae in as straight a line as possible to an underwater plate beneath the mast foot. This should be copper, bronze or monel, not sintered and not embedded into the yacht’s hull, as electricity prefers to exit via an edge. This arrangement creates what is known as a ‘cone of protection’ within which people are relatively safe provided they are below deck, sitting as high above the waterline as possible and well away from the mast.

The American approach is similar but greater attention is paid to the possibility of side flashes, which may be particularly damaging to electronics and may even blow holes in the hull. This is the reason for the USA preference for electrically bonding all underwater components, such as seacocks, engine, drive and rudder. The cable used is of considerably heavier gauge than is needed for purely galvanic purposes. It is believed that this practice forms a cage-like network of conductors, helping to protect anything within it.

Further problems arise in the case of secondary paths from the main, vertical, path of the current and any other possible routes, particularly any with high impedance. In this case the electricity can follow alternative, unpredictable routes to the sea, resulting in serious damage and risk to life. Again, bonding helps to reduce the likelihood of secondary paths but may have an adverse effect on corrosion.

View attachment 151953

View attachment 151954

Not sure this link is effective now Vyv...... When lightning strikes
Edit forget this as Coopec has it sorted....

 

[franksingleton]

Friends are ours we're in Mexico in a 56ft cat with carbon mast no lighting protection installation. The marina was full of yachts with masts. A big lightning storm went through. The only boat hit in the marina was a motorboat. No mast. Close to the water. Our friends were 4 boats away. How does that work?

We went through a very nasty lightning storm motoring between Bonaire and Grenada. We were in the lightning for several hours. Very nerve wracking. Lightning all around us. Some horizontal lightning going over us. No strike. We were in Florida at anchor in West Palm Beach. A nasty lightning storm went over us. A very close strike to the surface of the water next to us. Electronics went mad. I had the wind instrument and depth guage on. Very odd reading whilst the lightning was going on. Mast head led light and deck lights taken out. No other damage.
My point is that getting struck doesn't seem to follow any pattern. You can insist that you have a lightning protection system saving the boat but who knows. We don't have one but we have never had a direct hit under conditions I was convinced we would get hit being the only pair of mast for miles about in open sea. I think if you sail in places like Panama or Florida the risks are far higher than the UK. A huge percentage of boats that spend the summer in Panama have had lightning strikes. Probably not worth the effort in the UK

I agree. Lightning strikes are inexplicable. Let me ex[lain our Lightningmaster experience.

Before fitting the Lightningmaster, our Raymarine wind indicator needle used to go berserk if we were near thunderstorms or, on occasion, even when there was a stronger electric field than normal. There is always a voltsge difference between atmosphere and earth. The needle would start to oscillate. Then the needle would spin rapidly. We would turn off the power and, eventually the static would disperse and all would be normal.

Our close encounter was south of Sicily, approaching Sciacca from Marsala. The Italiam forecast was, “Isolate temporale.” It was a hazy day. Then, we saw fishing boats all heading for Sciacca. The, we saw a massive thunderhead appear out of the mist, followed by an enormous crack of lightning. We heard sizzling as the air was ionised. The wind indicator gave a little flick. That was all. We had heard nothing previously, had no warning and had not put any of our handheld electronics in the fridge. Nothing was damaged, cell phone, laptop, handheld VHF, fixed electrics.

Obviously, the Lightningmaster had had a beneficial effect. Whether it would have saved us in a slightly different situation, I do not know. I just know that it stopped the build up of static that had happened on about 1/2 a dozen occasions previously. I emphasise, it is not a protection system. It is a strike prevention system. Whether it would always work, I do not know. I just feel confident enough to say that, at a low cost, it APPEARS to do what the manufacturer claims. On that basis, I think that it is worth fitting.

 

[William_H]

A lightning strike is initiated by a leader from ground (sea) to cloud. This ionisation provides the incentive for strike to come down to ground with a huge current. It does seem that pointed conductor on mast top can dissipate static build up at a lower voltage possibly averting a real strike.
The problem is that GRP and wood tend to have some electrical conduction enough to carry the lead current. When the main strike comes down the high voltage will force conduction through seemingly insulated material producing a huge heat in pushing through resistance. hence trees explode and GRP can be blown apart.
The best option seems as said to connect the good conductor ali mast to sea with as little resistance as possible. Heavy wire mast base to metal keel is best, easiest arrangement. Yes heavy wire which if conducting high current may in fact melt/vaporise but still conduct the current.
For centuries church steeples have been apparently protected by copper strips from steeple top to ground. Yes fairly hefty copper but still not that big for currents expected.
Do not connect shrouds to the sea. The ss wire has significant electrical resistance so even in minor or nearby strike the wire will over heat and lose strength. Rely on ali mast with low resistance.
In any nearby strike the huge current increasing at a rapid rate works like a transformer to produce a magnetic field which induces current and voltage into any nearby conductor. Hence electronics can be affected or destroyed. At least disconnect wiring and if possible put in oven where metal box will divert induced voltage.
In the end the map of likely lightning strikes is very useful. UK and to a lesser extent Perth West oz where I am are pretty much free of lightning. so I do not worry. ol'will

 

[coopec]

The best option seems as said to connect the good conductor ali mast to sea with as little resistance as possible. Heavy wire mast base to metal keel is best, easiest arrangement. Yes heavy wire which if conducting high current may in fact melt/vaporise but still conduct the current.
For centuries church steeples have been apparently protected by copper strips from steeple top to ground. Yes fairly hefty copper but still not that big for currents expected.
Do not connect shrouds to the sea. The ss wire has significant electrical resistance so even in minor or nearby strike the wire will over heat and lose strength. Rely on ali mast with low resistance.

Well I think I've got something right? Maybe?

Instead of using a square plate to dissipate the electrical charge I've used X4 metal strips as I've read the lightning charge is dissipated through the sharp corners of the metal and there a lot more sharp edges on a strip rather than a square plate.

I've bolted a copper strip (25mm X 3mm) from the bottom of the mast to an external 1.5m strip attached to the outside of the hull. I suppose you will tell me the lightning will blow a hole in the bottom of the hull?

On top of that each shroud is attached to a metal grounding strip. All the strips are attached internally to the diesel engine.

 

[William_H]

Well I think I've got something right? Maybe?

Instead of using a square plate to dissipate the electrical charge I've used X4 metal strips as I've read the lightning charge is dissipated through the sharp corners of the metal and there a lot more sharp edges on a strip rather than a square plate.

I've bolted a copper strip (25mm X 3mm) from the bottom of the mast to an external 1.5m strip attached to the outside of the hull. I suppose you will tell me the lightning will blow a hole in the bottom of the hull?

On top of that each shroud is attached to a metal grounding strip. All the strips are attached internally to the diesel engine.

Hi Clive No I would suggest you have done more than reasonable to avert lightning damage. The bolt presumably between metal strip inside and metal strip outside of hull might be melted but hopefully leave a manageable hole in hull. Plus anything can happen with a lightning strike. ol'will

 

[franksingleton]

This might be of interest - Lightning Protection Theory: More Fuel for the Debate

 

[Ian_Edwards]

I've often wonder how I could protect my southerly 46RS from lightening strikes.
The the boat has a carbon mast, it is 7/8th rigged, with a dyneema backstay, air draft about 23m, so often the tallest mast around.
The only metal bits going to the mast head are the aluminum mainsail track and the cables for the; VHF, tricolor/anchor light, wind sensor and a SEAME radar transponder. All fine gauge copper, the biggest being the copper braid on the VHF co-axial.
Carbon fiber is a good conductor, but the epoxy matrix isn't. It's virtually impossible to make an electrical connection to the carbon, the fibers and covered in epoxy.
The boat also has a 4 ton ballast plate recessed in to the bottom of the hull, from forward of the mast to the engine bay. This provides several square meters of potential contact with the sea, but it is covered in an epoxy barrier coat and CopperCoat. The rod rigging is bonded to the grounding ballast plate with heavy gauge braided copper straps.
I can't see an obvious way to provide any protection.
I guess that if the mast received a direct strike, the epoxy would break down and the carbon would conduct, probably shredding the mast!
I don't worry about it, sailing in the NW of Scotland, thunderstorms are rare.
Is there any information on lightening strikes on carbon masts, and how to protect them?

 

[justanothersailboat]

How do I make a high amp connection through my hull without it turning into a hole if lightning blows it up? Is it, for instance, actually safe to earth the mast to a keel bolt? I worry that if I try to do something about lightning and it's not right, it might make things worse - and I also worry that it seems to be the kind of area where reasoning can be a trap as the actual behaviour can be counterintuitive. I am mostly trying not to worry about it on the basis that the boat hasn't been sunk by lightning in 42 years or lost electronics to one in about 20 so the risk surely can't be all that high in England.

 

[geem]

How do I make a high amp connection through my hull without it turning into a hole if lightning blows it up? Is it, for instance, actually safe to earth the mast to a keel bolt? I worry that if I try to do something about lightning and it's not right, it might make things worse - and I also worry that it seems to be the kind of area where reasoning can be a trap as the actual behaviour can be counterintuitive. I am mostly trying not to worry about it on the basis that the boat hasn't been sunk by lightning in 42 years or lost electronics to one in about 20 so the risk surely can't be all that high in England.

I wouldn't worry about it in the UK. The UK rarely sees the kind of aggressive lightning storms we have encountered in Florida or the Western Caribbean in Summer.

 

[RunAgroundHard]

Well I think I've got something right? Maybe?

Instead of using a square plate to dissipate the electrical charge I've used X4 metal strips as I've read the lightning charge is dissipated through the sharp corners of the metal and there a lot more sharp edges on a strip rather than a square plate.

I've bolted a copper strip (25mm X 3mm) from the bottom of the mast to an external 1.5m strip attached to the outside of the hull. I suppose you will tell me the lightning will blow a hole in the bottom of the hull?

On top of that each shroud is attached to a metal grounding strip. All the strips are attached internally to the diesel engine.

This is interesting. I have 25mm x 3mm copper strapping running from my mast support around the boat, engine bay and onto a copper sintered grounding plate. I was told that it was for a SSB radio (not fitted when I purchased the boat). All my seacocks were also connected to it. At a refit the bonding to the seacocks was was removed, GRP hull, assumption was not needed.

The history of my boat is vague but I do know that she went across the Atlantic and had a few USA things on her when I bought her. I am now wondering if she was fitted with lightening protection. The copper strap is still in the hull, but it is incomplete. Really neat installation, direction changes are by folding the strip, not cutting and joining.

Anyway, just an observation.

 

[justanothersailboat]

RunAgroundHard - 25mmx3mm copper strapping sounds a lot like the kind of lightning conductor fitted to buildings. I think you're right to guess it was a lightning protection system. IF it turns out that just running that from mast down to keel bolts is sufficient - then that would be a relatively easy step to fit - but I'd hate to assume that. Anything else sounds possibly very involved and harder to weigh up against the risks, especially outside high-lightning regions.

 

[geem]

RunAgroundHard - 25mmx3mm copper strapping sounds a lot like the kind of lightning conductor fitted to buildings. I think you're right to guess it was a lightning protection system. IF it turns out that just running that from mast down to keel bolts is sufficient - then that would be a relatively easy step to fit - but I'd hate to assume that. Anything else sounds possibly very involved and harder to weigh up against the risks, especially outside high-lightning regions.

On commercial builds these would be known as down conductors. The on flat roof buildings there would be parapet with a conductor running all around the building parapet and down conductors every few metres. These down conductors share the voltage/current of a lightning strike between them. On a typical building there would be several down conductors terminating in the ground with earth rods. I don't know how effective a single 25x3mm copper strip would be dealing with several million volts.