Electrolysis

[Guest]

I have recently had to renew my propellor as it was pronounced irrepairable due to electrolysis. There has never been any anode on the boat. I have no room to fit a shaft anode. Has anyone used 1 of the nuts which both secure the prop and have a zinc anode attached. Also if I have to fit a through hull anode how do I bond the shaft to the anode.

 

[Miker]

I had the same problem as you a few years ago. I only had a magnesium prop anode on which did not last more than a month or two then I moved the boat from fresh to sea water. I now know better!

I have an anode on the hub of the prop. I think that these are purpose made for the particular prop and only last three to four months on my boat. As well, I have a shaft anode and a hull anode. The latter is bonded to the shaft by an electro eliminator purchased from Cruisermart. The eliminator is a carbon brush which fits around the shaft. There was a good contact then I last tested but the prop and shaft anodes are the ones that are being eaten through.

I hope this helps and I will be interested in other replies.

 

[jfkal]

Are you on shore power? If yes make sure you get isolator diodes installed in the grounding line.

 

[Miker]

Re: Shore power and anodes??

My use of shore power is restricted to occasionally charging up the batteries via a Sterling charger. Do I still need diodes to prevent excess erosion of my anodes and, if so, where do I put them?

 

[incognito]

Re: Shore power and anodes??

read http://marinesurvey.com/yacht/corrosion_1.htm for full info. Note that this may not apply to your situation. If you do need to fit a 'galvanic isolator', you should get a proper one, Cactus do one. I fitted one myself, took about an hour, cost over £100, probably quite unnecessary, but nice for feel-good factor.

 

[incognito]

My ref should have been...

http://marinesurvey.com/yacht/corrosion_in_marinas.htm

 

[Guest]

How to make your own galvanic isolator, cheap.

Go to this URL.

http://www.yandina.com/galvanicIsolator.htm