Extra wire in lightning ground system?

[wikakaru]

Yesterday I was hooking up the battery in my CD22 and found an extra wire I hadn't noticed before. I traced it back to the DynaPlate mounted in the bilge several feet forward of the battery storage area. It is my understanding that the DynaPlate is for the optional lightning ground system rather than a bonding system. None of the bronze seacocks on the boat have any bonding wires running to them, so I have to assume this is the lightning system. Here's what the manual says:

3.18 LIGHTNING GROUND SYSTEM

Your Cape Dory is equipped with a lightning ground system installed in accordance with the American Boating and Yacht Council (A.B.Y.C.) specifications. Every shroud and stay is connected to an external ground plate by a #8 A.W.G. stranded copper wire. Other equipment requiring bonding include the engine, fuel tank, mast step and fuel fill cap. Within practical working restraints, the wires are lead directly to the ground plate. (Note - Typhoon and CD-22 have optional lightning ground systems.)

While no one can predict how lightning will react when it hits a spar, we know from actual experience that this system offers added protection.

During a lightning storm refrain from touching any metal objects such as shrouds, mast, stanchions, pulpit, etc., as these may attract lightning.

Do not paint the external ground plate with bottom paint as this prevents the plate from grounding out with the seawater.

Periodically inspect the connections in the bilge to see that they are tight and clean and free from corrosion.

That's all the manual says. No drawing, nothing. So according to the manual, the lightning ground system on the CD22 must just be for the standing rigging, since my CD22 has no engine, no fuel tank, and no fuel fill cap.

I'm wondering why this wire is run to the battery area. Every drawing I've found of lightning protection systems omits a wire to the negative post of the battery. If I'm not mistaken, the area under the battery is where an optional diesel engine could be installed in the CD22. Maybe they ran this wire for the engine block connection in the lightning grounding system for the extremely unlikely eventuality that an engine was installed? I don't think many CD22s had diesels, so to fit all CD22s with this wire doesn't seem to make sense to me.

Could it be that there were at one time two more wires split off from this one that were connected to the bronze cockpit drain seacocks that are not too far away, and that the other seacock under the sink was also once connected but no longer is? But it doesn't make sense to me that a lightning system and a bonding system would have been connected together, and there is no evidence that such wires ever existed.

I welcome your speculation on the purpose of the wire and what, if anything I should do with it. It seems like a bad idea to connect it to the battery negative terminal, which is the only thing in that area, as that would just feed any lightning strike right into the whole DC system.

Thanks!

Jim

The extra wire in question. I know what all the other wires here do.

20220604_155751 Ground wire with arrow.jpg

The DynaPlate attachment in the bilge that the wire runs to. Looks like I need to do some cleaning!

20220604_155740.jpg

[Keith]

I believe that when they refer to the lightning ground system and the bonding that they are talking about the same system.

Keith

[Steve Laume]

On Raven all external metal goes to the grounding plate. The DC grounds all go to the engine or a buss bar that I added that ties everything together before going to the neg battery post. The engine does not go to the grounding plate.

Who knows if this is in line with current thinking but that is how they did it back in 1984.

[wikakaru]

I believe that when they refer to the lightning ground system and the bonding that they are talking about the same system.

Keith

The manual has separate entries for the lightning ground system and the bonding system, which makes it sound like they are separate systems, though, also according to the manual, they both connect at the DynaPlate and engine block, so as you say it seems to be one system with dual purpose. Here's the section on the bonding system from the manual:

3.17 BONDING SYSTEM

All thru hulls and seacocks below the waterline, including the stern tube, are connected to one another, to the engine block and to the external ground plate with a continuous loop of 18 copper wire. This is done to minimize the effects of electrolysis should one fitting become “hot” for any reason. Generally, a fiberglass hull is considered to be non-conducting and as such the chance of stray electrical currents forming is minimal. (Bonding system is standard on all diesel equipped Cape Dorys.)

As more and more electrical equipment is added to a boat, it becomes increasingly important to BE ALERT TO THE THREAT OF ELECTROLYSIS. We recognize that there are various types of instrumentation available to further monitor strong currents and any potential difference between ground and the thru hulls. These instruments can all be added to the supplied ground wire system. It is highly recommended that a sacrificial zinc be installed on the shaft (see shafting section).

From the manual it sounds like the "lightning" part of the system connects the shrouds and mast step (and, if the boat is so equipped, the engine block, fuel tank, and fuel fill cap) with the DynaPlate using #8 AWG wire, while the "bonding" part of the system is a loop of #18 AWG wire that connects the seacocks (and, if the boat is so equipped, the stern tube and engine block) to the DynaPlate.

I can find no evidence of the bonding part of the system on my boat--there are no #18 AWG wires laying around in the bilge, and based on the other disused wires laying about the boat I can't imagine that any of the previous owners would have gone to the trouble to actually remove it. The manual says the bonding system was only standard on diesel equipped Cape Dorys, so I have to assume no bonding wires were ever installed on my boat.

The wire in question is #8 AWG, so if the manual is correct it must be part of the lightning rather than bonding system.

--Jim

[wikakaru]

On Raven all external metal goes to the grounding plate. The DC grounds all go to the engine or a buss bar that I added that ties everything together before going to the neg battery post. The engine does not go to the grounding plate.

Who knows if this is in line with current thinking but that is how they did it back in 1984.

Thanks Steve. Now we have three systems under discussion: lightning, bonding, and grounding! My boat's grounding system is similar to yours: it all connects to a bus bar behind the DC panel that connects to the negative post on the battery.

It's interesting that the engine block on your boat doesn't connect to the DynaPlate. That's different from what the manual says. I wonder if it was removed at some point or never installed to begin with.

Is there an external sacrificial zinc anode on your boat apart from the one on the prop shaft? Current ABYC standards call for an external anode on a bonding system, and the DynaPlate is definitely not a sacrificial anode.

--Jim

[s2sailorlis]

My '84 22 has the same plate, and yes it's the lightning "system". Personally the shoelace size wires connected to mine wouldn't seem to do much good in a strike but who knows.

You mentioned the negative bus bar in yours. So you know if that's OEM? My factory wiring is close to a rats nest where they got lazy and just tied all the neg wires together and threw on some solder resulting in a massive blob... very unprofessional...

[bottomscraper]

Grounding plates were also used for Loran (and Ham or Marine HF Radio).

[wikakaru]

My '84 22 has the same plate, and yes it's the lightning "system". Personally the shoelace size wires connected to mine wouldn't seem to do much good in a strike but who knows.

You mentioned the negative bus bar in yours. So you know if that's OEM? My factory wiring is close to a rats nest where they got lazy and just tied all the neg wires together and threw on some solder resulting in a massive blob... very unprofessional...

I agree that lightning systems are generally inadequate, especially aboard fiberglass boats. The only boat I ever had that I felt reasonably comfortable about lightning protection was the 35-foot steel cutter we lived aboard for more than a dozen years. The whole hull was basically just one big lightning ground. All the shrouds, stays, and mast were connected to stainless chainplates welded to the hull, so lightning could get to the water through multiple paths. We went through lots of severe lightning storms, some of which had so many strikes that it looked like a strobe light was running--dozens of strikes per second. We smelled ozone from nearby lightning strikes more times than I can count. Several times during lightning storms adjacent fiberglass boats were struck and suffered extensive damage. Our steel boat was struck by lightning once: when it was hauled out in a boatyard and the hull was sitting on 8x8 wooden blocks so there was no electrical path to ground. Even then, damage was minimal. We lost the masthead wind indicator (literally blown to pieces) and the VHF antenna. I think that was it.

No, the bus bar is not original to our CD22. Some previous owner had actually had the good sense to install a negative bus bar behind the electrical panel, but had the bad sense to mount the bus bar inside the boat by running screws from outside the aft side of the cabin house into the electrical space. The screw heads were just sitting right there for God and everyone to see. It really bugged me. During Arietta's refit at Lackey Sailing over the past two winters, Tim Lackey removed the old bus bar, patched all the holes in the cabin house (and everywhere else in the cockpit), repainted the decks, and installed a new bus bar.

Here's the old bus bar installed by some previous owner:

hw11-120120.jpg

You can tell by all the butt splices that are only a few inches from the bus bar that however the common ground used to be made, it had to be chopped apart and redone.

Here's the outside view that shows phillips head screws that used to bolt the bus bar in place (plus various plugs for items no longer used):

deckinsp2-120120.jpg

Here's what the outside looked like when Tim got done:

instruments21-122121.jpg

Here's what the bus bar looks like now: https://lackeysailing.com/wp-content/up ... 123021.jpg
(I've used up my 3 photos for this post, so this one's a link to the photo on Tim's site.)
It's still a bit of a rat's nest behind the electrical panel, but fixing that is a job for another time.

If you are interested in the refits in detail, here they are:
Year 1: https://lackeysailing.com/projects/arietta/
Year 2: https://lackeysailing.com/projects/arietta-phase-2/

Smooth sailing,

Jim

[John Stone]

I think there has been a change of view regarding bonding--wiring all the underwater metals together. I don't think it is viewed as positively as it was in the past. I'd read up on it to see what the thinking is today. Make sure your sources are up to date. Lightening protection is separate but related. The thinking is mixed on grounding a boat for lightening protection. Only metal boats are truly protected.

I have read everything there is to read on lightening protection. The "experts" do not know exactly how lightening works with regards to it striking a sail boat though there are lots of ideas and theories. The FR is ungrounded. James Baldwin who sailed his Triton around the world twice does not ground his boat. Many other long distance sailors do not ground their boats. Many others are grounded. If it was a certainty that grounding protects your boat it would be required by insurance companies. But it's not.

The only facts that I can determine regarding grounding sailboats for lightening protection follows.

1. Sail boats are hit more often in fresh water than salt water.
2. Cats are twice as likely to get hit as monohulls.
3. Grounded boats get hit slightly more often than un-grounded boats.
4. Boats grounded suffer slightly less damage than ungrounded boats.

I have seen the pictures of hull damage suffered by un-grounded boats as well as grounded boats. Looks similar to me.

When I was a kid our family 40' ketch was hit in south FL. Blew the VHF off the mast. Blew the amp gauges across the saloon. The VHF radio was not damaged. The electrical system was I damaged other than those two gauges. Someone explain that to me. The starboard cap shroud turnbuckle was fused together. The boat was ungrounded.

I think this is one of those areas in sailing where you have to pick a position that reduces your anxiety in an electrical storm on your boat.

I freely admit lightening is one of the few things that scares the crap out of me when I am sailing.

[s2sailorlis]

Very nice! I have a bus bar lying around and my plan was to epoxy it this not needing any holes. On my gettoit list. Pix below is my “trailer park bus bar” from the factory..tape removed of course.

And thank you for posting the links.

My '84 22 has the same plate, and yes it's the lightning "system". Personally the shoelace size wires connected to mine wouldn't seem to do much good in a strike but who knows.

You mentioned the negative bus bar in yours. So you know if that's OEM? My factory wiring is close to a rats nest where they got lazy and just tied all the neg wires together and threw on some solder resulting in a massive blob... very unprofessional...

I agree that lightning systems are generally inadequate, especially aboard fiberglass boats. The only boat I ever had that I felt reasonably comfortable about lightning protection was the 35-foot steel cutter we lived aboard for more than a dozen years. The whole hull was basically just one big lightning ground. All the shrouds, stays, and mast were connected to stainless chainplates welded to the hull, so lightning could get to the water through multiple paths. We went through lots of severe lightning storms, some of which had so many strikes that it looked like a strobe light was running--dozens of strikes per second. We smelled ozone from nearby lightning strikes more times than I can count. Several times during lightning storms adjacent fiberglass boats were struck and suffered extensive damage. Our steel boat was struck by lightning once: when it was hauled out in a boatyard and the hull was sitting on 8x8 wooden blocks so there was no electrical path to ground. Even then, damage was minimal. We lost the masthead wind indicator (literally blown to pieces) and the VHF antenna. I think that was it.

No, the bus bar is not original to our CD22. Some previous owner had actually had the good sense to install a negative bus bar behind the electrical panel, but had the bad sense to mount the bus bar inside the boat by running screws from outside the aft side of the cabin house into the electrical space. The screw heads were just sitting right there for God and everyone to see. It really bugged me. During Arietta's refit at Lackey Sailing over the past two winters, Tim Lackey removed the old bus bar, patched all the holes in the cabin house (and everywhere else in the cockpit), repainted the decks, and installed a new bus bar.

Here's the old bus bar installed by some previous owner:

hw11-120120.jpg

You can tell by all the butt splices that are only a few inches from the bus bar that however the common ground used to be made, it had to be chopped apart and redone.

Here's the outside view that shows phillips head screws that used to bolt the bus bar in place (plus various plugs for items no longer used):

deckinsp2-120120.jpg

Here's what the outside looked like when Tim got done:

instruments21-122121.jpg

Here's what the bus bar looks like now: https://lackeysailing.com/wp-content/up ... 123021.jpg
(I've used up my 3 photos for this post, so this one's a link to the photo on Tim's site.)
It's still a bit of a rat's nest behind the electrical panel, but fixing that is a job for another time.

If you are interested in the refits in detail, here they are:
Year 1: https://lackeysailing.com/projects/arietta/
Year 2: https://lackeysailing.com/projects/arietta-phase-2/

Smooth sailing,

Jim

[wikakaru]

I think there has been a change of view regarding bonding--wiring all the underwater metals together. I don't think it is viewed as positively as it was in the past. I'd read up on it to see what the thinking is today. Make sure your sources are up to date. Lightening protection is separate but related. The thinking is mixed on grounding a boat for lightening protection. Only metal boats are truly protected.

I have read everything there is to read on lightening protection. The "experts" do not know exactly how lightening works with regards to it striking a sail boat though there are lots of ideas and theories. The FR is ungrounded. James Baldwin who sailed his Triton around the world twice does not ground his boat. Many other long distance sailors do not ground their boats. Many others are grounded. If it was a certainty that grounding protects your boat it would be required by insurance companies. But it's not.

The only facts that I can determine regarding grounding sailboats for lightening protection follows.

1. Sail boats are hit more often in fresh water than salt water.
2. Cats are twice as likely to get hit as monohulls.
3. Grounded boats get hit slightly more often than un-grounded boats.
4. Boats grounded suffer slightly less damage than ungrounded boats.

I have seen the pictures of hull damage suffered by un-grounded boats as well as grounded boats. Looks similar to me.

When I was a kid our family 40' ketch was hit in south FL. Blew the VHF off the mast. Blew the amp gauges across the saloon. The VHF radio was not damaged. The electrical system was I damaged other than those two gauges. Someone explain that to me. The starboard cap shroud turnbuckle was fused together. The boat was ungrounded.

I think this is one of those areas in sailing where you have to pick a position that reduces your anxiety in an electrical storm on your boat.

I freely admit lightening is one of the few things that scares the crap out of me when I am sailing.

I agree, John. I think lightning is one of those things that chaos theory applies to: even knowing all that modern science knows about electricity, atmospheric ionization, and all the other factors involved, the complexity of arrangement of all the elements between a cloud and the water (including the boat) means that predicting exactly what will happen when lightning strikes is virtually impossible. One time it can throw an ammeter across the saloon, and another time it can leave a boat completely unscathed.

My feeling is that I don't want to make an easier path for lightning to get into my electrical system. Not that it is a complex system--just a VHF radio and some lights--but one of the boats that was hit nearby our steel boat had to replace every light fixture and nearly every wire in the boat. Connecting the battery negative to the DynaPlate just seems like it would provide such a path into the electrical system. I am sure that lightning can find a way in there even with the wire not in place, but my gut feeling is that such a connection would just make it easier for the lightning. So I plan to leave that wire permanently disconnected from the battery.

--Jim

[fmueller]

Here is a good article. It’s VERY complicated to get it truly correct.

https://aqualitz.ca/index.php/marine-grounding-systems/

[wikakaru]

Here is a good article. It’s VERY complicated to get it truly correct.

https://aqualitz.ca/index.php/marine-grounding-systems/

Thanks for that link, Fred! I haven't seen that article before. A couple of interesting pieces of advice from it:

Do not rely on a thru-hull or a sintered bronze radio ground (e.g. Dynaplate) for use as a lightning ground.

Oops, that's exactly what Cape Dory did.

The lightning ground needs to be a direct DC connection to the keel or to a ground plate to handle currents due to lightning strikes. So how do we keep the keel or ground plate electrically isolated as required in “Bonding and Electrolytic Corrosion…” above? The solution is to connect the keel or ground plate directly to the mast, but make sure the mast is not electrically connected to the boats DC ground system.

That confirms my decision not to connect the wire in question to the battery. I'm just going to leave it unattached.

--Jim