I have a large cable that extends from my aft stay into the bildge area. At the bildge end, there is a large battery clamp. Is this a ground? where do you clamp it? Cheers.
Randy,
When you say large cable I'm assuming something like 0 gauge. This sounds like part of some lightning protection scheme that connects the standing rigging to a large underwater piece of metal. In this case it sounds like maybe the V-drive. That would allow the current to pass to earth via the prop. Your PO must have had some scary close calls or direct hits.
This connection is already made through the bonding system so the cable seems redundant. But I'm not sure if a direct hit would fry those 10 gauge wires. I have 2 large cables that run aft but they are for the battery box in the aft anchor locker.
It could also be a low impedance ground for a long wire radio antenna.
I'm in the process of going over all the wiring in my boat. Step 1: Any wire that is connected at only one end is coming out, and there are a lot of them. I have equipment hot wired that needs to be placed on breakers and the H/B/E battery bank selection makes no logical sense.
Pete W.
Pete,
It's like a battery cable. With a battery cable type clamp on one end. I could clip onto V-Drive? Could'nt hurt, right?
my lightning ground is screwed into my ballast...
I guess there are alot of different approaches to lightning protection. Wonder which one really works?
I have had an interesting discussion with a Power Company Engineer who is also a sailor. They are really interested in avoiding lightning strikes and have studied lightning extensively. The short version is there are things that will help avoid a hit, but not as much as you might like to think. If you are hit you need a good path to ground, and the worst part is that unless you have a metal hull you won't get enough grounding surface in fresh water.
Deo Volente conveys a good sense of the problems with lighting protection in fiberglass boats.
http://www.nasdonline.org/document/209/d000007/boating-lightning-protection.html
Here's a good little article that gets into the facts. What I take away from this is that the bonding system, as designed into the Pearson boats, is your best bet for providing the cone of safety. The bonding system connects every underwater piece of bronze to the mast. Beyond building a special conductive bronze plate onto the keel and connecting it directly to the mast, what Person did is correct. 8 AWG wire is sufficient as there is a lot of resistivity with your conection to earth. A battery cable seems over optimistic.
My first boat, a Dufour, connected the mast to the keel via a gas discharge tube. The article does suggest that a direct electrical connection to ground can actually increase your chances of getting struck.
I'm an EE and this all makes sense.
Pete W