I have looked over previous posts about bonding, not bonding, AC, DC separation. Not looking for input on pros or cons at this point. My survey says I need to redo the bonding cable between the mast and keel bolt, and the insurer is asking for the work to be completed. My question is what do others use as a connector between bonding cable running from the mast to the keel bolt? On our N22 there was just corroded bare wire (AWG4) squished under a hose clamp around the top of the keel bolt and the wire had rotted off slipped out. I had a look at the local chandlrey and could not see a ring connector large enough to slip over the keel bolt. Are there any other connectors that could do this job securely? Maybe battery connectors. Not sure if they come in the size required, I believe the keel bolts on the 22 are 3/4". Thank you. Bill.
I don’t see a problem with using a hose or other type of clamp to simply make the connection to the keel bolt. The idea of using a battery post clamp sounds like a great idea if it fits. Crimp, do not solder any wire connections. The following is from a West Marine article -
Lightning Ground
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. If your steaming light, masthead light, tricolor, Windex light etc. are wired carefully and correctly, they each will have their own DC return wire; there should be no ground connection between their wiring and the mast itself. Make sure that this is the case.
This should also be true of your masthead instruments. The unintended DC connection between mast and DC ground is typically made by the masthead VHF whip, which connects the shield of the coax to the bracket connected to the mast. That shield also connects to the VHF radio which is DC grounded by its power connection. The easiest solution is to insert what is called a “inner-outer DC block” into the coax.
This RF device puts a capacitor in series with the center conductor, and another capacitor in series with the shield. This device is transparent to the VHF RF signals in the center conductor and shield, but blocks any DC current in either the center conductor or shield. This device can be made by a good radio technician, or purchased from radio supply houses, pre-fitted with any kind of coax connection on both ends. The commercial units look like a coax “barrel” connector. A vendor is listed at the end of the article.
Once the DC connection from the mast to the VHF is broken, check for any other connections with an ohmmeter, and straighten out any other wiring errors or unintended connections. If your metal fuel tank is also bonded to the lightning ground system (per ABYC) then make sure that it does not have DC connections either to the engine via the fuel line or to the electrical system via the fuel level sensor. A piece of approved rubber fuel hose in the fuel lines to the engine solves that connection, and a well designed fuel level sensor will not make electrical contact with the tank.
When you’re done, there will be heavy conductors running from the external keel or lightning ground plate to the mast, stays, and to the metal fuel tank, but there will be no DC connections to the engine or to the yacht’s electrical system. See Figure 3.
Joe Valinoti
S/V IL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
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