Lightning Protection - for deck stepped mast

[Snowgoose71]

I have a 1998 Beneteau 352 and a few days ago was inspecting and cleaning the keelbolts.....there was a wire with ring clamp over one of the bolts. I assume this is a ground wire for the mast but the other end of the wire could not be found.....I looked under the flooring and in the inspection area by the compression pole...can someone tell me where I might find the ground wire or at least how it is configured from the mast / compression pole / keelbolt.

Additionally, there is a ground wire from the chainplate to another keelbolt.....but only one (starboard side) is grounded. Is this typical....why not port as well? I've included a picture also where the chainplate looks like it connects to some sort of surge protector (sitel). The black wire also connects to the seacocks in the head. What would this set up to the sitel device do / protect?

Thanks for replies! Trying to stay safe from lightning.

[tkeithlu]

From the size of the wire I have to conclude that the goal is to channel a lightning strike to your keel.

Lightning striking is a matter of static electricity, so it will strike the tallest, sharpist point arround, meaning your mast, independent of conductivity. Having struck, it is conducted electricity at a voltage and amperage that is way outside the experience of us mortals. It may consolidate and all go down one conductor, probably vaporizing it in the process, or decide to spread out and melt all your electronics, or travel down some fiberglass and send bits flying. No telling, and the variety of experiences when it happens is, shall we say, striking.

OK, so Beneteau tied your mast and standing rigging to the keel. Good. It's no guarantee that that whopping bolt will not go down multiple routes, but at least it means that it will not reach the bottom of your deck-mounted mast and hull-mounted chain plate and then look around for new conductive opportunities. The connection to through hulls I think recognizes that they are often the way out for a bolt. Why they didn't do both sides and the fore and aft stays is another question. I don't know.

[Snowgoose71]

Sorry left one picture out....here is the wire that was connected to keelbolt....I don't think the other end was connected to anything (perhaps severed at one point or just corroded through).

[Frankly]

Does not look even close to a proper lightning down conductor. On a deck stepped mast best to just connect a large stranded/ tinned wire to mast lower end and other end to keel bolt (run through compression post).

As to why only one cap shroud, one better than none but not as good as two.


Frankly

[vpbarkley]

I have a 2010 Beneteau 40. The port chainplate is connected by a large cable to a keel bolt. As I don't see any other cables connected to any of the remaining keel bolts, I suspect there is a but single connection to ground. This wiring looks factory. The starboard chainplate is not connected to ground.

[hernandobeach]

For openers, lightning is broad spectrum energy. From DC to high frequency elements that are in the 300MHz range. Think of it a Mother Nature's best example of a static discharge. It is seeking to remove any difference in potential. Small non stranded cables are almost worthless.

Second, remember Ohm's Law I=E/R. To make it easy to understand. Take1 billion (volts) and divide that by 20 (ohms). Your "I", "the current" is 50 million. Now do the same math with "1" as "R" Your answer is 1-billion. That is the current the "R" developed and follow the path you have created. Where do you think the rest of that current is going to go?

Think of a surge protection device, (SPD), it is an electronic toilet...... it gets rid of a large amount of "electric crap" you don't want in your systems or equipment. Depending on the design of the SPD it will have the capability to divert "X" energy and with luck and the proper SPD dissipate what it cannot divert.

The path, to divert is like the drain line on a toilet. When was the last time you flushed a toilet in a home on a 1/2" drain line and had good results? The "1/2" drain line is a high resistance grounding and bonding path. Stuff goes where you least want it.... all over your "stuff".

Simple, you want a conductor that will allow current flow with VERY low resistance and impedance. Also remember lightning does not like hard turns. I have worked for a number of boat manufacturers and each one of them today now does the bonding right, uses large conductors (equal to 2/0 - 4/0), most use stainless steel as the corrosion issues are present. They use large surface area connectors, a very large bonding point and coat all with conductive grease to protect the connections.

I am a power boat person, had a boat with a very tall tower and out riggers. That is not bonded properly and with an excellent ground path were trouble. I also have friends that have sail boats with very tall rigs. When I was at dock I had two very long over 50' braided stainless steel lines equal to a 3/0 that I put into the water on both sides of the boat. My sail boat friends started doing the same thing...... after they fixed all the improper bonding in their boats as I did in my boat...... guess what, no damage on my part except the VHF Radio on the fly bridge.

The key, help lightning go where it wants to go and don't get in the way.............

I hope this helps all who face the lightning exposure while boating..