Corrosion

Keithleask

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2 Jun 2013
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Just wondering if any forumites are berthed at MDL Chatham maritime and have experienced any unusual corrosion levels either galvanic or leakage / stray currents from other boats. Shore power etc? Will explain more depending on any replies, thanks
 
I have heard a few knowledgable people discussing the electrolysis at Chatham. It's a bit of an issue apparently.

Google is your friend...
 
Is the water fairly fast flowing there?

From what I have read, the difference in corrosion rate (anodes) between still water & that flowing at 5 knots can be about 10x.

The marina I'm in is known for eating anodes. The high tidal difference plus narrowing of the river there means the flow can be 5-6 knots a lot of the time.
 
I think it is an issue my anodes were junk in less than 7 months with collateral damage to drives and transom shield looking at a huge bill !!
 
I think it is an issue my anodes were junk in less than 7 months with collateral damage to drives and transom shield looking at a huge bill !!

I had similar. Had to replace my gearbox & trim rams! This was partly due to underestimating the speed at which my anodes would deteriorate (gone in three months!), partly due to missing continuity circuit wires and partly due to a non-functioning MerCathode. I replaced the missing wires and faulty MerCathode and added a couple of big anodes on the transom in addition to those on the drive. All seem to be lasting much longer now and no sign of corrosion on the leg.

I don't know what kind of drive you've got but have a read of this Mercruiser manual extract: http://www.boatingwithtr.com/members/pdfs/7a_28.pdf. The principles are the same for most drive types.
 
Thanks speaking to Rob who does Grp repairs and he said he had fitted larger anodes for a number of owners who had similar problems
 
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