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Old 03-26-2017, 06:33 AM   #21
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Guess I would not worry about lightning on a power boat. If hit it will destroy all the wiring between it and the bonding.
Unfortunately, this attitude is shared by the manufacturers of the electronic equipment on most boats.
My current line of work is hardening electrical substation electronics from surges and lightning strikes. I routinely expose sensitive electronic ciruits to direct injections of 2 to 5kV pulses. Utilities and their customers don't care to loose power if even a direct strike occurs in the switchyard. In my desk are many, many types of devices that absorb, reroute, or otherwise mitigate what I will call "very close strikes". Yes, it is possible to take a hit that will melt steel cabinents. Most direct strikes won't do that.

Other stories: An airliner receives, on average, one direct strike per year. Many are now fly by wire, and have fundamentally higher susceptability to surges. They survive, in no part due to engineeering design.

I have a radio system at home. My antenna took a direct strike about 2 years ago. The radio was connected, turned off. Zero radio damage, although the antenna itself melted one conductor and I had a pure plastic insulator explode due to trapped water from the rain. Many ground rods, even in clay, and suitable grounding straps helped tremendously. Cell sites do similar treatment.

My message is simple. It is possible to harden boat electronics. Don't accept devices like electronic diesels unless they are surge hardened. These manufacturers, I believe, just don't care.
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Old 03-26-2017, 07:21 AM   #22
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ABYC calls for #8 AWG. The reason is not current carrying bu structural. They know that these cables will be in the lowest portion of the hull and will be stepped on and therefor physical strength is the controlling factor. The braided straps are not permitted by ABYC. I was ABYC tech VP 11 years.
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Old 03-26-2017, 07:26 AM   #23
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ABYC calls for #8 AWG. The reason is not current carrying bu structural. They know that these cables will be in the lowest portion of the hull and will be stepped on and therefor physical strength is the controlling factor. The braided straps are not permitted by ABYC. I was ABYC tech VP 11 years.
Is the copper foil of old still used/OK for the backbone?

I would think it would be the connections to it that are now the issue with using it.
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Old 03-26-2017, 07:54 AM   #24
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Regarding lightning protection,
I dock with lots of sailboats nearby.
However, out fishing, you never know . I would imagine being up on plane getting out of there, but then my main mag plate would be high and 'dry'.
That infers question 1. Is it grounded? #2 is where is the top target area of the lighning wire -hooked to a rod?
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Old 03-26-2017, 07:55 AM   #25
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I will be in the bilge today so will check replies later.
Thanks in advance!
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Old 03-26-2017, 07:57 AM   #26
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My Egg Harbor was built with a bronze rectangular ground buss bar 1/4 thick by 3/4 wide by 15 feet?, running along the keel to which bonding wires are run from all metal fittings and fuel tanks. Bolts were drilled into the bar to attach on the wires. OEM used solid copper 10 gauge insulated wires. No wires were broken, all insulation still intact. All ring ends still ok. All ok even being from 1970. Solid bonding wires must have not been considered a problem in the old days. Frankly water has a harder time seeping along a smooth round wire than a multistranded wire inside of the insulation, less wicking. And even if it does get wet, being a solid wire with much greater size of the individual strand, so less corrosive possibility than with many strands wicking water. I really think such a wire is better as a bonding wire than a multistrand wire.

Nowhere can you step on them to damage them. Being a wood boat it has large frames- floors every 9 inches which have bonding wires running under these floors where they intersect to the keel, which in a house you would call joists.
I went through all of them when I rebuilt the hull in 2006. Some I need to take apart and clean as they are turned green the ones attaching to the shaft logs. Probably need to clean and grease with marine grease. Marine grease is water resistant, regular grease water slowly but steadily dissolves the grease. In the past, I noticed using regular greases, the grease eventually disappears and certainly does not prevent corrosion when salt water gets things wet..

Being wood hull, I disconnected all bonding wires to water through hulls as otherwise delignification has been a proven problem with wood boats. I left everything else connected.

When I rebuilt the hull, I moved the engine raw water thru-hulls to a new location, and the wood under there was a mess, but easily fixed with a steel brush, wood backing block, round wood plug, and polyurethane goo and screws.
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Old 03-26-2017, 07:59 AM   #27
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There is a lot written about lightning and boats, but so little of it seems conclusive on how to avoid or distribute a stike....so I really don't give it much thought/worry, but I avidly read about it in case there is a breakthough.

After the post on hardening electronics, other than putting them in Faraday cage like protection, microwaves, etc....I would be interested in how to do it for each piece if possible.
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Old 03-26-2017, 07:59 AM   #28
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Is the copper foil of old still used/OK for the backbone? I would think it would be the connections to it that are now the issue with using it.

The copper foil should still be fine. The goal is make it strong enough that it does not get broken when stepped on or kicked.
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Old 03-26-2017, 10:05 AM   #29
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I'm planning to replace some old solid () bonding wire on my boat with tinned, stranded green marine cable. My plan is to use 10 AWG green wire from Genuine Dealz.

Does this sound about the right size? Another section of bonding cable is a braided non-insulated strap like this. It looks like it's in very good shape. Is this proper and sufficient?

I think you might want to take a look at this before you do anything to your system. HTH JD Understanding The Green Ground Wire - BoatUS Magazine
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Old 03-26-2017, 10:45 AM   #30
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I think you might want to take a look at this before you do anything to your system. HTH JD Understanding The Green Ground Wire - BoatUS Magazine
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Old 03-26-2017, 04:59 PM   #31
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I agree on the solid wire theory of the 1970 Egg Harbor regarding moisture wicking...
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Old 03-27-2017, 09:04 AM   #32
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look closely at the 2 hose clamp ends and the bonding wire. Looks like a chance for chafing to me.

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Old 03-27-2017, 09:11 AM   #33
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Here is a view that disputes the long standing view of an underwater "discharge plate". Thomson argues that you want a number of waterline discharge points that basically direct the lightning bolt onto the surface of the water. That's where the water charge had developed from the cloud attraction charge. But, still, you need high current paths for the discharge current, from up high, surrounding the vessel, and then to the "Siedarcs" at waterline, or just above.
The U of F has done lighting simulation and modeling in response to electrical utility requests. I have a couple different electronic products mounted either on independent pedestals or on transformers directly, outside throughout Florida. About 700 in total. The largest threats are due to cabling, and their ability to pass lightning transients directly to semiconductors. So far, my stuff has sustained very little surge damage, over about 5 years now. A boat has very similar issues. Radios are very much in harm’s way. The antenna mounts high, and conducts directly into a circuit that is made to listen to signals in the 0.5 microvolt area. Hit that with 500 kiloVolts which is a thousand million times higher. So, even indirect strikes are hostile. Engines: electronics with remote sensors, and gauges. All these cables, typically unshielded, pick up these transients and carry them to the engine ECM. The electronics dies. The engine dies. The engine is fairly well grounded. It is an excellent catch for these very high currents, taken through cabling and taking that through the sensitive electronics on its way to ground/water through the transmission and shaft/prop.

Taken from Marine Lightning Protection Inc. | Yachting Magazine



The marine industry’s long-standing lightning protection language urges boat builders to put a one-square-foot grounding plate along the keel, connected to the mast, arch or other part high in the structure with heavy-gauge wire and to the ship’s bonded underwater metal fittings. Thomson says his research contradicts that wisdom.
During his tenure as a researcher and associate professor at the University of Florida in Gainesville, Thomson authored several influential papers on lightning physics, including lightning in a marine environment. He collaborated with other experts in writing standards for the American Boat and Yacht Council and National Fire Protection Association. In 2001, he left academia to found Marine Lightning Protection Inc. His company developed a system — and patented some of its unique equipment — that Thomson and a growing number of marine industry people believe can save lives and make marine electronics less likely to be ruined by a strike.
Thomson’s system works by creating, in effect, a Faraday cage around the boat and its occupants. This invention is named after Michael Faraday, who in 1836 discovered that an enclosure of conducting materials shielded its contents from electrical effects and could be used to protect against lightning.
Starting from the top of a fiberglass (or carbon fiber) vessel, Thomson’s system uses one or more air terminals (lightning rods) attached to other system components with heavy-gauge cable. Thomson looks for existing metal structures, such as a Bimini frame and deck rails on a powerboat or the metal bow and stern pulpits or toe rails on sailboats. In the ideal scenario, these structural conductors are as far outboard as possible and make at least one circuit around the outside of the boat. They are then bonded to a series of Siedarcs, electrodes made of copper rod, honed to a point and potted with epoxy in a through-hull fitting, installed at intervals just above the waterline.
Thomson developed the Siedarc after years of forensic examination of lightning-struck boats showed that the area above the waterline was frequently hit by side flashes — high-voltage sparks that cause damage, injury and possibly death. Thomson’s system calls for at least two grounding strips beneath the water rather than a traditional metal plate. He urges that these grounding strips be attached high on the hull, closer to the waterline than the keel, but he thinks these hunks of metal play a less important role than previously believed.
“The idea behind the ground plate has been that it somehow conducts current into the water and then down to China — that’s been the concept,” Thomson says, launching into an analogy. “On a battery you have a plus terminal and a negative terminal. Hook a wire up to the positive and a wire to the negative and put something like a light in the middle. Charges flow from the battery through the light, give it energy and then go back to the battery again. That’s an electric circuit. Lightning, when it hits the boat, is effectively a wire to the charge in the clouds, through the boat to the water. But what’s the return path from the water to the cloud to make a complete electric circuit? It makes a huge difference when you realize that this circuit is not going to China; it’s not even going into the ground. The current goes back into the sky, but the way it gets there is from a charge on the surface of the water.”
Trying to force this massive charge out through a ground plate at the bottom of the vessel is a bad idea because water is a medium that impedes the process, like impedance in an electrical circuit.
Thomson argues that conventional notions about grounding plates are ineffective and potentially dangerous. Routing lightning through the interior of a vessel to a plate near a mast step can force a charge to build up at the center of the boat and cause the side flashes that threaten the crew and electronic gear.
The National Fire Protection Association worked closely with Thomson to incorporate his principles in its 2008 standards for watercraft safety. NFPA recognized that his system is similar to lightning protection on a building, channeling the charge to ground along the exterior, rather than the interior, of a vessel.
Ewen Thomson and his ideas have proved troubling to the American Boat and Yacht Council (ABYC). It has balked at following the lead of the NFPA, some members of which have argued that ABYC’s long-standing lightning protection standard, which includes the centralized ground plate, should be eliminated from its catalog altogether. Instead, the ABYC in 2006 downgraded its lightning protection “standard” to a “technical paper,” intended to carry less weight among boat builders. At the same time, some of the language was modified to accommodate Thomson’s new ideas, but without specifically recommending or even explaining his Siedarc technology.
The ABYC’s lukewarm endorsement has not stopped a growing cadre of yacht designers from recommending Thomson’s system. Since the first installation, more than 30 vessels have received the Siedarc system, including a Great Harbour 37, a Nordhavn 55, a Nordhavn 62, the circumnavigating 60-foot power-cat Domino II and a 140-foot catamaran to be finished at the Pendennis Shipyard in the United Kingdom.
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