Stray Current

[Babu]

My neighbour in the marina suffered severe corrosion to the aluminium prop on his saildrive, to the extent of having to replace same. Somewhere I read an article on testing for stray current but can't find it again. Can anyone point me in the right direction? (I have a feeling he thinks I'm to blame)

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[DeeGee]

Was he connected to shore power? Is there a circuit from his bonding to the shore-power earth?

If boat is out of water, put a meter on the propshaft to the hull anode. Then check to the s/p earth.

If there is a connection from prop to s/p earth, then there can be a connection to steel pilings, steel boat hulls.... with the seawater electrolyte you have a big battery. Answer is a galvanic isolator 100 or so squidlets.

<hr width=100% size=1>Black Sugar - the sweetest of all

 

[oldsaltoz]

If the Marina has steel piles there is a good chance the have impressed cathodic protection, this means they run a current through the water to prevent the steel piles being eaten away. So an alloy boat or prop will become anodes if not protected.

Avagoodweekend......



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[pladda]

One of our club members found this article, its very good, worth reading.

http://www.loughswillyyc.com/sections.php?op=viewarticle&artid=37

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[Babu]

Thanks for the replies. The shore power aspect makes me think. He is permanently plugged in with a float charger on all the time. Maybe trashed his own prop.

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