Does every shroud need to be bonding connected?

[s/v Jedi]

Originally Posted by team karst

THere is a fair amount of evidence that you don't want to 'steer' lightning current far below the waterline. You want to "encourage" lightning current to discharge right at the waterline. Several sailboats that run heavy wire bottom of mast to the metal keel suffer a side discharge thru the hull at waterline. sometimes resulting in a sinking. If you think about it, the charged cloud overhead will draw electrons at sea surface. Its that surface charge that want to move electrons, not subsea water.

I should have added that my recommendation is for keel stepped masts on monohulls.

There is full evidence that my recommendation is 100% effective, namely our own boat has demonstrated it many times (we’ve been hit 5 times or more). Even direct hits that evaporate vhf antennas, windex, B&G wind sensor etc. are transferred to the seawater with zero damage to the hull.

[geoleo]

I have a 41ft Beneteau with a Iron wing keel. There are 2 # 8 copper wires from the shroud fittings to the keel bolts from each side. There isnt a grounding plate . Mast is deck stepped with a pst thru cabin to keel. Is this adequate?

[team karst]

Originally Posted by s/v Jedi

…



….we’ve been hit 5 times or more). Even direct hits that evaporate vhf antennas, windex, B&G wind sensor etc. are transferred to the seawater with zero damage to the hull.

Wow, impressive strike count!
I believe we wont have robust countermeasures for electronics until wireless and fiber make inroads on boats. Even with that will remain the vhf antenna problem.

[s/v Jedi]

Originally Posted by team karst

Wow, impressive strike count!
I believe we wont have robust countermeasures for electronics until wireless and fiber make inroads on boats. Even with that will remain the vhf antenna problem.

My current fiberglass antenna survived 2 strikes… must be coincidence.

I am also building an isolated power source for electronics. Should work well, but I guess we’re never gonna get a hit again

[Kelkara]

How does one connect a lightning ground wire to an aluminium mast? Normally you'd try to electrically insulate any bolts from the mast to prevent corrosion ... but this kind of requires electrical conductivity.

[s/v Jedi]

Originally Posted by Kelkara

How does one connect a lightning ground wire to an aluminium mast? Normally you'd try to electrically insulate any bolts from the mast to prevent corrosion ... but this kind of requires electrical conductivity.

We use the mast step, which is aluminum as well. I was surprised how little corrosion there was… probably the strikes cleaned it up or something haha

Crimp a tinned battery lug to the cable, connect to the mast step or very base of the mast and use plenty dielectric grease. This is one of those connections to check regularly.

[GordMay]

Originally Posted by team karst

THere is a fair amount of evidence that you don't want to 'steer' lightning current far below the waterline. You want to "encourage" lightning current to discharge right at the waterline...

Indeed.
Dr. Ewen Thomson wrote the book on Lightning Protection for Boats, and is the founder of Marine Lightning Protection Inc. (MLP ), and developed the new patented SiedarcTM electrodes that can be faired into the hull to reduce drag and require only a single hull penetration.

Further, they are preferably installed (just) above the waterline, thereby eliminating galvanic corrosion.

His website is a great source of information:
➥ Marine Lightning Protection Inc.

[s/v Jedi]

Originally Posted by GordMay

Indeed.
Dr. Ewen Thomson wrote the book on Lightning Protection for Boats, and is the founder of Marine Lightning Protection Inc. (MLP ), and developed the new patented SiedarcTM electrodes that can be faired into the hull to reduce drag and require only a single hull penetration.

Further, they are preferably installed (just) above the waterline, thereby eliminating galvanic corrosion.

His website is a great source of information:
➥ Marine Lightning Protection Inc.

All that is for catamarans only. If you try this on a monohull with keel stepped mast, the lightning will strike straight through the hull under the mast instead of traveling back up a conductor to above the waterline.

A catamaran has the mast step high above the water on the bridge deck. They must move sideways with the conductors because the bridge deck is suspended over the water. Still, some catamarans have damage (lightning may decide to not make the 90 degree turn and go straight down through the bridge deck. The good part is that this doesn’t sink the cat, which is unsinkable anyway) and decide to have a wire through the bridgedeck hanging in the water (but stop shirt of the water would be fine too).

I think it’s important that people reading this understand that this is very different for the different boat types.

Then there are monohulls with deck stepped masts. I would not want to take the risk of making the 90 degree turn and would hope that the mast step makes an electrical connection to the mast step which has an electrical connection to the compression post so that it becomes the same as a deck stepped mast.

I have seen the aftermath of a direct strike to the masthead for a boat without this protection and it had a million little holes in the hull, all the way from deck level to the keel.

[maury]

“Then there are monohulls with deck stepped masts. I would not want to take the risk of making the 90 degree turn and would hope that the mast step makes an electrical connection to the mast step which has an electrical connection to the compression post so that it becomes the same as a deck stepped mast.“

Your 90 degree comment is interesting. At one point I mentioned a chain hanging from base of a shroud dangling down i to the water. By shroud connected it eliminates to 90 degree issue and chain gets it to the surface of the water where it has been stated is best place to dissipate the energy. Upper shroud or lower shroud? Assuming hit is at highest point I would guess upper. Also I just remembered I have a lot of old stainless cable I will soon be tossing. Why not just connect a 6’ piece and let the end hang down with a safe fitting on the end.

[s/v Jedi]

Originally Posted by maury

“Then there are monohulls with deck stepped masts. I would not want to take the risk of making the 90 degree turn and would hope that the mast step makes an electrical connection to the mast step which has an electrical connection to the compression post so that it becomes the same as a deck stepped mast.“

Your 90 degree comment is interesting. At one point I mentioned a chain hanging from base of a shroud dangling down i to the water. By shroud connected it eliminates to 90 degree issue and chain gets it to the surface of the water where it has been stated is best place to dissipate the energy. Upper shroud or lower shroud? Assuming hit is at highest point I would guess upper. Also I just remembered I have a lot of old stainless cable I will soon be tossing. Why not just connect a 6’ piece and let the end hang down with a safe fitting on the end.

The problem is that the lightning tends to come down the mast, even when you have a shroud grounded with a chain hanging overboard.

Of course the lightning can strike the shroud instead of the masthead. But I don’t feel like you want to take the risk because grounding the base of the mast has been proven effective.

The 90 degree turns…. any turns really but it gets worse as the turn gets sharper, should be avoided because the lightning will not comply and rather ionize the air into plasma to take the shortest route.

[Statistical]

Maury,

Lighting protection is very complicated and honestly IMHO a bit of a voodoo science just due to the unpredictable nature of lighting. When you are talking a million volts it can take whatever path it wants. Like from my service days the joke about what side of the road do tanks drive on? Whatever side they want.

The conductors also have to be reasonably large and low resistance. If they are small and high resistance they will simply instantly melt and then the lightning will seek out another path.

If you want I will email you a copy of TE-4 ABYC Lighthing as long as you don't turn me into the ABYC police. Just PM me an email address. I fear that just getting partial answers could be worse than no information at all. Read all of TE-4 and then you can ask questions to fill in knowledge.

Note even ABYC calls this a technical report (hence the TE not E) which means they aren't regs the way E-11 or E-30 are more best practices based on current limited knowledge. This is a tactic admission by ABYC that honestly we don't really know 100% for sure. All you can do is best practices. Boats with lighting protection have been destroyed. Boats without lighting protection have walked away with just some minor electronics damage. Lightning is very unpredictable.

Again as I said about the best lightning mitigation method is insurance. Even with lightning protection and everything working reasonably well and you discharge the majority of the strike outside the hull smaller arcs can jump off the main branch and fry electronics. To be honest it is more "lightning damage mitigation" not "protection". The word protection implies a certainty that just doesn't exist.

[s/v Jedi]

Originally Posted by Statistical

Maury,

Lighting protection is very complicated and honestly IMHO a bit of a voodoo science just due to the unpredictable nature of lighting. When you are talking a million volts it can take whatever path it wants. Like from my service days the joke about what side of the road do tanks drive on? Whatever side they want.

The conductors also have to be reasonably large and low resistance. If they are small and high resistance they will simply instantly melt and then the lightning will seek out another path.

If you want I will email you a copy of TE-4 ABYC Lighthing as long as you don't turn me into the ABYC police. Just PM me an email address. I fear that just getting partial answers could be worse than no information at all. Read all of TE-4 and then you can ask questions to fill in knowledge.

Note even for ABYC calls this a technical report (hence the TE not E) which means they aren't regs the way E-11 or E-30 are more best practices based on current knowledge. This is a tactic admission by ABYC that honestly we don't really know 100% for sure. All you can do is best practices. Boats with lighting protection have been destroyed. Boats without lighting protection have walked away with just some minor electronics damage. Lightning is very unpredictable.

Again as I said about the best lightning mitigation method is insurance. Even with lightning protection and everything working reasonably well and you discharge the majority of the strike outside the hull smaller arcs can jump off the main branch and fry electronics. To be honest it is more "lightning damage mitigation" not "protection". The word protection implies a certainty that just doesn't exist.

This is true, but loosing electronics is another scale than loosing the boat due to sinking. The method I described will not protect electronics, nor prevent a lightning strike, but it is 100% effective in guiding the strike safely to the water.

When boats with this system sunk anyway, then something was wrong, like a cable corroded away or wrong installation etc.

[Bowdrie]

Originally Posted by s/v Jedi

The problem is that the lightning tends to come down the mast, even when you have a shroud grounded with a chain hanging overboard.

Of course the lightning can strike the shroud instead of the masthead. But I don’t feel like you want to take the risk because grounding the base of the mast has been proven effective.

The 90 degree turns…. any turns really but it gets worse as the turn gets sharper, should be avoided because the lightning will not comply and rather ionize the air into plasma to take the shortest route.

^True this.
I will posit that a long-term weather forecast for the South Pole is probably more accurate than predicting what a lightning strike will do.
That said, we DO know that it does not want to make sharp turns.
The straightest/most direct path from mast/mast step to a keel/keel bolt is still one of the most effective ways to minimize the effects of a strike.
You start with that as the basic/beginning step, whatever layers of "protection" that you want to add after that is open to all kinds of postulation about effectiveness.

[GordMay]

Originally Posted by s/v Jedi

All that is for catamarans only. If you try this on a monohull with keel stepped mast, the lightning will strike straight through the hull under the mast instead of traveling back up a conductor to above the waterline...

Dr. Thomson installs his system on both multi and mono* hulled sailboats, and powerboats

The science and technology of yacht lightning protection
➥ Science & Technology

* Guidelines for layout, components and installation of (Siedarc) lightning protection system on Outbound 46
➥ Guidelines for Outbound 46

[wholybee]

I currently have no lightning protection on my boat. One of those things on my long list, but as my home port doesn't get lightning, not very high on that list. But, I do ponder how I would do it.

I have a keel stepped mast, and encapsulated keel. The mast sits in a bucket, and the bucket is about 2 inches above the lead, with a glass filler of some sort on top of the lead. I assume the bolts for the step penetrate to the lead, but I am not positive. So I could probably create an electrical connection between the mast and lead keel if it doesn't already exist.

But I don't want the lighting to blast sideways out of the keel through my hull either. Do I install a plate on the side of my keel, with lag bolts that go into the lead? Is that wise?