Paint on Lightning Protector

[coopec43]

Strike By Type Of Boat

Type of Boat............ Chances per 1,000
Multihull Sailboat.................. 6.9
Monohull Sailboat................. 3.8
Bass Boat............................0.1
Runabout........................... 0.1
Pontoon Boat...................... 0.1
Overall Average................... 0.9

https://www.boatus.com/magazine/2017...strikes.asp0.9

[Wallaby]

Having been whacked by electrons and had my vessel totaled by the insurance company, because of damage to electronics...
What saved my hull was bonding every bronze thru-hull, keel, Dynaplate, and engine. When the boat was hauled, the surveyor looked for the 'exit wound.' He could not find it. However, every thru-hull and 2-3" around it had lost its anti-fouling--Micron 66 (high copper). The yard owner and I pointed it out to the surveyor, who said it was the result of electrolysis!


The lesson for me was a) ignore surveyors, and b) make sure lightning has as many clear, 'smooth' exit paths as possible.

[captmikem]

For what it is worth:

My boat, a KP46 cutter was struck by lightening at my dock in Ft. Lauderdale. All the thru hulls were bonded to the rig. On haulout I found the bottom of the depth sounder blown out with about a ¾ inch hole. Luckily it did not leak water into the boat. The wire going to it appeared normal.

Of note, other than destroying just about everything electronic on board, the following physical damage was found:
The VHF antenna at masthead was blown off, the ICOM SSB had a fire Inside but no flames escaped to start anything else. The Xantrex inverter/charger had all of the triacs blown apart. The AIS/VHF coupler was melted inside the metal box. The alternator controller had the SCRs blown apart.

M

[tkeithlu]

Nice examples of what I described at the top of the thread. Now, about catamarans. If annoyed thereby, and a storm is approaching, run a jumper cable from your standing rigging to the standing rigging of the cat. If you do take a hit, the jumper cable will vaporize, thereby destroying any evidence of prejudicial behavior on your part. Be sure your insurance is paid up.

[thunderhoof]

Hi,
I am interested in your ship's lightning protection scheme but I am unclear on exactly how it is implemented.
Is the copper plate on the exterior of the hull with the parallel 1/0 wires piercing the hull and then connected to the mast near the step?
Thanks,
Dick Hohol
Blue Agave

[waterman46]

Originally Posted by RaymondR

Lightning conductor or ground bleed for the bonding system it's best not to have it's conducting function impaired by covering it with an insulator.

I have read that a grounded lightning rod helps to dissipate static charge in the immediate region of the rod. This is supposed to reduce the chances of a conduction leader forming in the same area. The conduction leader always forms just before the actual strike. The rod being a sharp point is supposed to be better at this behavior than a flatter surface, but whether is is any better than just the top of a mast is probably unclear.
But my point is that a reasonably low resistance path to ground, not impeded by layers of paint, may allow better performance of the mast or rod in reducing local static charge in the region close to the mast.

[Djarraluda]

Basically, electricity is a lazy brighter, it looks for the easy path. What starts out looking tempting may deteriorate and the charge thus changes its path.
Many a bonding cable failed due to a bend, especially in the bilge where it is damp!
A tall rig nearby attracts the charge but then a better earth path is “seen” nearby and so the lightning seems to be attracted only to the lower mast.
The old adage of hanging chain from rigging into water works well in a storm, perhaps not always the best at a dock though.
Roger

[Mike Banks]

If you look in the archives you will find quite a bit of argument and useful information on the lighning phenomenon and the many interesting aspects of it.

Suffice to say that lightning protection is better then no protection, and that on my vessel the earth plate for my radios and radar was separate entirely from the discharge plate for the lightning protection system.

Because a lightning "Strike" depends entirely on the ionic path available to a charged portion of the atmosphere to conduct it to earth, and because the atmosphere is in constant swirling motion, the chance of an unprotected vessel being struck is low--but present at all times. One does not need to be in a storm or impending storm to be struck by lightning, but such strikes are rare--and when they do--a "Bolt from the blue", they tend to be severe.

So--if it is your radio-radar earth, do not paint it--and if it is part of a lightning array, do not paint it either, because lightning requires an ionized path, and discharging as much of that path through your system will significantly lessen the chance of a strike.

I used to work in the telecommunications industry and I can assure anyone interested that without lightning protection and arrestors on telephone terminals and radio, television and microwave towers , there would be a lot more damage and a lot more dead people using them during a storm.

I know the discharge of the area surrounding an installation using lightning protection does occur, because some of those voltages get high, and if one used a gaseous arrester to earth that equipment, when the charge density exceeded 120 volts or so--the arrester gas at low pressure ionised by the charge and the arrestor would discharge it to earth with a crack.

A gaseous arrester would not go astray on any radio antenna on a boat especially if it is high up the mast.

I would not be putting a copper arrester on an aluminium mast. A metre long rod
of aluminium 15 to 20mm thick, one end ground to a point the other end clamped to the mast will work just fine and not cause dissimilar metal corrosion.

Now all you need do is connect the mast step to the earth plate for the lightning conductor, and this ideally needs to be directly below the mast and connected to the mast by heavy aluminium or copper wire, but connected to the aluminium using a compatible connector--or copper will corrode the mast.

[Frankly]

Dick,

The copper plate is on the exterior of the hull nearly directly below the mast step. The four silicone bronze bolts form the conductive path between the plate and the 1/0 wire. Although the lugs connecting the wire to the base of the mast are plated copper, i used a paste for aluminum wiring. Check the connections every 5 or so years, but appears as initially installed (15 years back).


Frankly

[Orion Jim]

Originally Posted by Sailor_Grant

On my 1978 Cape Dory 27, there is a lightning ground metal plate built into the side of the full keel. This grounding plate is attached to the backing plates for the chainplates.

The grounding plate is currently painted over with antifouling paint. Is this okay?

This was a 1978 design, so a lot of new information on lightning has been found since then. Does this system even work?

You can see a copy of your owners manual here CDSOA, Inc. -- Groups & Publications

This excerpt from my manual is quite clear that the ground plate should not be painted.

[coopec43]

Originally Posted by Orion Jim

You can see a copy of your owners manual here CDSOA, Inc. -- Groups & Publications

This excerpt from my manual is quite clear that the ground plate should not be painted.

When I was about to put the barrier coat on and anti-foul I was told by an "expert"(?) that it should not be painted over.

Also I've read that the lightning strike exit through the edge of the plate - not the flat surface. I have therefore have X4 strips about 1.2M long.

Although a thunderstorm may only last for an hour or so, its enormous power is ... A long strip is more effective at dissipating the electrical flow than a square plate of the same area. ... As far as possible from the lightning protection system

https://www.clubmarine.com.au/explor...htning-strikes

[Disailor]

After having been caught out in a T'storm on my first boat (Fried my digital watch), I attended a lecture on lightning at the Atlantic City Sailboat show. The man giving the talk had a business that installed lightning protectors on communications towers. He was located on the SW corner of Florida in an area that has the most lightning strikes per year & he mentioned how they would shoot wired rockets into the clouds.
As the static charge in the cloud builds, a shadow charge forms on the ground & follows along underneath the storm. When that shadow has a tall object (tree, bldg, mast etc) within it, the charge rises to the top of said object & since the area of the top of the mast, (ie) it becomes concentrated until it can connect. First are faint "feelers" that begin to ionize the air. When sufficiently ionized the air conducts. His company developed what looks like a steel bottle brush. The ends of each bristle dissipate charge before it can build.
It is hotter than the surface of the sun. It takes 1,000,000 volts to jump a meter, so paint on a grounded plate is inconsequential.
When the lightning strikes there is an electric field that builds & then collapses when the strike is over. Any metal wire/railing etc within that field will generate a voltage at the first & second field collapse. The voltage can jump (sideflash) from lifelines/railings to the wheel, down the steering to the rudder post. Electronic gear should be installed for very quick removal & place inside the oven (a Faraday cage). The mast provides a 45 degree "cone of safety". Lightning will not strike within that cone, however side flashes can happen. I carry 2 auto jumper cable sets that are separated into 4 cables. I clamp one end onto the shrouds & throw the other overboard.
While blowing insulating into the exterior wall of a house one August, I was standing about 3 feet up an aluminum ladder. I heard a T'storm coming & thought it was far enough away, however, a strike about 3 miles away generated enough voltage to energize my leg muscles (wearing shorts) enough to involuntary jump back off the ladder. Got up off the ground & called it a day.

[waterman46]

It seems a good ground for lightning would be a large copper conductor hung from rigging shrouds into the water, and each conductor having a number of inch wide, maybe 2 ft long thick gauge copper straps at its end. This could be left in place while not underway.

[RaymondR]

I has always assumed that the steel hull of my previous boat would act like a Faraday cage and consequently had nothing to fear regarding the electronics provided I disconnected the antennas of my HF and VHF radios.

A nearby strike which destroyed my laptop and TV set disabused me of that assumption.

[mickt243]

Originally Posted by Wallaby

Having been whacked by electrons and had my vessel totaled by the insurance company, because of damage to electronics...
What saved my hull was bonding every bronze thru-hull, keel, Dynaplate, and engine. When the boat was hauled, the surveyor looked for the 'exit wound.' He could not find it. However, every thru-hull and 2-3" around it had lost its anti-fouling--Micron 66 (high copper). The yard owner and I pointed it out to the surveyor, who said it was the result of electrolysis!


The lesson for me was a) ignore surveyors, and b) make sure lightning has as many clear, 'smooth' exit paths as possible.

surveyor may not have been wrong, as such.... quite possible it was electrolysis, and it all happened in a few milliseconds whilst there was a high voltage, heavy current flowing from the standing rigging to the water via said thru hulls etc....