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Galvanic Isolator


Baz

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Following the fitting of Mains power to my boat, I asked a question on another Broads website, about the fitting of Anodes. The response was great, and it was also suggested that I fit a Galvanic Isolator. Well, I looked on several different websites, and each of these showed their wares, great I thought, but they advertised the isolators showing different values, ie. various Amps. Now, is there a certain formula I should follow, or is there someone who can describe the differences to me, and what should I purchase.

As of yet, I have no idea what the Rudder,Shaft, or Propeller are actually made of as I haven't had the boat out of the water to check on sizes etc. The boat is GRP, with a Diesel Inboard engine, a Seamaster 27 in fact, with a through the hull shaft to propeller.

I've come over to this site really to get as many comments as possible, so as to make the correct purchases.I have also read the previous thread on the subject of Anodes, very interesting.

Regards

Baz :Stinky

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Where are you moored Baz? as that will affect the composition of the anode(s) you need, the prop and rudder metal will be irelevant as they will all be above any anode material you may fit on the galvanic scale. If you do need a galvanic isolator, that is to say there are stray currents in your marina, then a Sterling Power 16a is what I usually fit, the shore supply is only 16a so nothing more is needed. Target Price is around £60, if you can't find one cheaper I do them at that price. The isolator can be fitted anywhere before the distribution box PROVIDED that no bonding is present before the splice you make for the isolator.

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Hiya,

Thanks for the quick reply, much appreciated. I'm at Broadsedge in Stalham. At present they are going through the installation of fitting shore power to the site, so thought I'd better get the boat electrified in readiness. What the power is going to be I'm not sure.

Regards

Baz

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In that case Baz, you will need Magnesium anodes, if you can get one of the MG Duff types that replace the prop nut for your shaft then those are by far the best as they have direct electrical contact with your prop, that is the most vulnerable part as it contains zinc which will react with the staniless of the shaft and can become dezinctified reducing its strength. As for stray current testing and the need (or not) for a GA you may find this of use.

http://www.boatquotes.com/abyc.htm

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Blimey, I've just read the link you supplied, very interesting, and to be honest, a real eye opener. Just goes to show that you can't be too careful.

I've just finished doing the wiring on the boat myself. I've used all stranded Blue cable ( Arctic ) bought from a well known charndler in Hoveton, going to a consumer unit with rcd, and 2 fuses, one of 16a, and one of 6a. The 16a goes to wall sockets, while the 6a goes to an isolator box for the 1kw immersion heater. When the shore power is up and running, it will be connected to the boat through a shore power lead and into a proper shore power connector in the boat, and from there, into the consumer unit. All mains cable is inside a plastic conduit that circulates the boat.

When it was completed, I connected it all to a 2kw petrol generator and checked each socket separately, and found all working.

Baz

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