Grounding log

[WI Rigger]

I read an article on installing a #6 electrical copper (not aluminum) wire lug at the bottom of the mast. In the case of an electrical storm, one could install a #6 insulated wire in the lug, the wire being long enough to reach approximately 3’ below the surface of the water. The wire below the water line would have the insulation stripped off so it is bare. Thus directing a lightning strike electricity into the water. Has anyone used this, and does it really work like it is intended?

 

[Don S/V ILLusion]

The consensus is that a grounded mast can direct a hit directly to ground (water). Not sure trying to connect the mast grounding wire at the last minute is a sound practice.
Why not make a permanent installation?

 

[WI Rigger]

By making it permanent, you would attach the ground lug to the mast step and NOT the mast itself. That way it does not have to be disconnected when I step the mast in the Fall? How do you attach it to the deck so it does not become a “trip“ hazard? From the edge of the deck to the water, is the wire allowed to just hang free?

 

[dlochner]

By making it permanent, you would attach the ground lug to the mast step and NOT the mast itself. That way it does not have to be disconnected when I step the mast in the Fall? How do you attach it to the deck so it does not become a “trip“ hazard? From the edge of the deck to the water, is the wire allowed to just hang free?

On larger boats the wire is connected either directly to the mast on keel stepped boats or to a mounting bolt on a deck stepped mast. From there it is run directly to a keel bolt in a straight a line as possible.

Frankly, in Wisconsin in a small boat, a lightning strike is has a pretty low probability of occurring. In an area like Vero Beach, Titusville FL strikes are more frequent because T-storms happen more often. I'm in upstate NY and in 40 years I haven't heard of a boat being struck by lightning. I have seen smaller boats blown off their trailers and breaking loose from their moorings, so I'd be more concerned about that than lightning.

Lightning protection and radar reflectors are 2 of areas in sailing that are ripe with mythology and poor science. Continue to research lightning protection and you will see what I mean.

 

[Don S/V ILLusion]

By making it permanent, you would attach the ground lug to the mast step and NOT the mast itself. That way it does not have to be disconnected when I step the mast in the Fall? How do you attach it to the deck so it does not become a “trip“ hazard? From the edge of the deck to the water, is the wire allowed to just hang free?

Mast step through deck, down post or bulkhead to keel and attached there or to a grounding plate, through hull, etc…

 

[WI Rigger]

Dave, What I find curious about lightning, no one is sure if it comes down or if in fact it originates in the earth and goes up. The visible bolt we see is the energy reflecting off the clouds of opposite polarity and coming back to its point of origin.

 

[Brian D]

Current flows from positive to negative, and voltage flows from negative to positive. The earth is negatively charged while the lower part of the cloud is positively charged. A circuit path is set up between the cloud and earth which creates a votltage. The air between the two resists the flow of current which is discharged from the earth to the cloud. The result is a flash of light as the air gets super heated. This is how I understand it and by no means am I a scientist.

 

[LloydB]

'What I find curious about lightning, no one is sure if it comes down or if in fact it originates in the earth and goes up. The visible bolt we see is the energy reflecting off the clouds of opposite polarity and coming back to its point of origin.'
My opinion is that even Ben Franklin knew more about lightning than that. From what I have read lightning goes either from earth to clouds and from clouds to earth at near the speed of light depending on where the charge has been built up. What you see is actually multiple discharges of lightning in the same path of discharge which has been discovered by high speed photography. My opinion of why we see the discharge is because when it goes through those water molecules it actually burns the hydrogen molecules although I'm sure there's more to it than that. From what I have read it seems to me like we are floating on the surface of a capacitor rather than sitting on top of a watery ground rod so the discharge will go to the surface rather than the depth below. At least that explains to me why we see holes through the hull at the water line when a lightning strike travels through a mast into a sailboat with a grounded keel.(usually but no personal experience)

 

[dlochner]

Lightning is a very large electrical discharge between 2 poles, the earth and the cloud forming what is basically a battery. Electrons are pretty lazy and look for the fastest and shortest way to a positive side of the circuit. When the lightning bolt hits something it takes the easiest fastest way to the positive side. If that path is through a through hull or out the side of the hull, that is where it will go. The holy grail for lightning protection is give the lightning a safe path to the positive pole (earth). Many have tried, few, if any have been successful.

(Note the positive side of a circuit, like a battery, is positive because it is electron deprived. The negative side of a battery is negative because it has an excess of negatively charged electrons.)

This article might be of interest.

Lightning Is Huge Factor in Rising Insurance Costs. Why Won't ABYC Help?

Only They Can Get Us Out of This Mess, Loose Cannon Argues

loosecannon.substack.com

 

[capta]

Some boats seem to attract lightning while others do not. Skipping Stone was often the highest mast in an anchorage, but she never took a lightning strike, while other boats anchored in the same anchorage with shorter masts did.
At any rate, I can't imagine that any size wire or cable is going to help divert a lightning bolt, as apparently they carry 300 million Volts and about 30,000 Amps. I know of lightning strikes that have blown a hole about a square meter through the hull, and others that sustained little damage to the boat, except for the electronics.
There was (is?) a company that developed a virtual Faraday cage to protect boats. They installed it on a boat and the boat took two lightning strikes in a couple of months. That boat had never been hit before the Faraday cage was installed, and never after it was hastily removed.
I'm afraid you are going to have to trust your luck on this one.

 

[JamesG161]

I will post this again and again.

I am an expert in Lightning protection.

I was taught many years ago by people who protect things like Water Towers.

Here is my best advice..

"Several types of sciences involved.
List in order of your ability to control them...
1) Electrical (flow of electrons)
2) Math (statistics)
3) Religion

If you combine all 3 you can reduce your chances of being a target.
In a nutshell...
1) Ground your boat and Isolate yourself
2) Buy Insurance
3) Pray it doesn't hit you"

_________
Faraday Cages do work, if installed properly. [example is your microwave]

Best Discussion on this subject is here...
newbie lightning protection?

Long thread but good.

Good Avoidance from Lightning in the future.
Jim...

PS: It does make a difference when sailing on Fresh Water[ok] versus Salt Water[best].

 

[JamesG161]

From a large boat Owner's Manual.



That Zone of "Avoidance" is the Faraday Cage effect. [Not Protection]
Jim...

 

[JamesG161]

Current flows from positive to negative, and voltage flows from negative to positive.

Current [Amps] is the only thing that Flows.
Analog for water would be "gallons per hour"

Voltage is the Potential to cause Amps to flow. Cloud's Voltage potentials are >10,000 volts.
Analog for water would be "pressure"

It is the water surface charge that is the key.

Sometimes, but rare, that charge can be Positive.
Jim...

 

[Brian D]

Semantics, Jim, semantics.

 

[All U Get]

I always get a charge out of reading these posts, but definitely not shocked.