Keel wired to anode?

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Keel wired to anode?

Post by Pethautwp »

Hi I was working through checking continuity between the anode on my corsair II and a few questions came up.
Currently the auto helm, engine and what I believe to be the unit that houses the cutlass bearing are all connected to the anode. There was a further wire that stopped (unconnected) under the fuel tank. The questions are

What should be connected to the anode?
What wire should be used as there are a couple of different types present?
Should the keel be connected?

The last question comes from the fact that there's a wire tape(a kind of mesh tape with an outer plastic sheath) connected to one of the keel bolts but this instead of leading to the anode as expected, this goes up behind the main switch panel where it's joined on to a brown wire that terminates shortly after. Any idea what this may have been for?

Thanks in advance

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Re: Keel wired to anode?

Post by mikebuggy »

1. Keel bolts are often used as an RF earth (radio earth). Totally separate and different purpose to the vessels DC earth. Used particularly if a HF set has been fitted. Do not connect to DC earth.
2. Keel bolts are also often used with a thick cable to the mast base as part of lightning protection. Again different from both RF earth and DC earth.
3. P bracket, engine, seawater inlet valve, and rudder stock/tube usually all linked and bonded (DC earth). Bonding cable should have a good diameter (ie NOT bedside light flex!!)
4. If you have a flexible coupling there should be a flexible cross-coupling bonding strap.
5. it is no longer considered neccessary (or wise) to bond other seacocks to the DC earthing system, as current advice is to limit the formation of active cells.
6. It is also possible to bond the incoming mains shore supply to ship's earth as well, but this is still somewhat subject to debate in some countries, and not commonly found on older pre-European Rules and non-commercial vessels. Where it is connected it is usually via a Galvanic Isolator in order to prevent stray currents from damaging your vessels fittings.
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