Anodes – An Interesting Question?

[annv]

And rather than have a anode on the prop shaft and run the risk of vibration through imbalance you should earth it via a slip ring unless it doesn't have a insulated anti vibration gear box output coupling or if so has a earth strap between shaft and gear box which then needs to be connected to the anode. John

[Cheesey69]

Had my sail boat on the Medway in a marina that dried out between tides. The boat hulls made a sort of lake in the mud in which our boats sat. 
it seem a boat nearby or even the pontoons earth return was faulty or corroded but my prop and anodes just vanished in 6 months. So I boughta galvanic  isolator that went in line with shore power cable and never had a problem again

[Vaughan]

46 minutes ago, Cheesey69 said:

So I boughta galvanic  isolator that went in line with shore power cable and never had a problem again

That is always a good option!

[NeilB]

1 hour ago, Cheesey69 said:

Had my sail boat on the Medway in a marina that dried out between tides. The boat hulls made a sort of lake in the mud in which our boats sat. 
it seem a boat nearby or even the pontoons earth return was faulty or corroded but my prop and anodes just vanished in 6 months. So I boughta galvanic  isolator that went in line with shore power cable and never had a problem again

I've heard of case's where they have disappeared in 6 weeks due to faulty wiring !  

[Cheesey69]

As a side note, I also switchEd off the 12volts at the main switch so nothing was drawing power (had no bilge pump, manual) and connected a multi meter to the terminals. 
Found a high reading in micro volts. Turns out the alternator was allowing power to back flow which would energise the engine at rest and to those anodes. 
New alternator stopped that