electrolysis

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Bob
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electrolysis

Postby Bob » Wed Apr 30, 2008 8:31 am

I recently had to replace both sets of blades on my folding props due to electrolysis. In fact I threw one blade and was fortunate that it did not come through the bottom of the boat. Has anyone else had this problem? The diver said the zincs were OK when he replaced the first set. The second diver tried to put the collar zincs that were missing on the port hub but one of the goles were striped. I have one hub with collar zincs and the other has no provision for them however I have a spare hub that is set up for them. I plan to carean the boat and make repairs to one hub and replace the other. Has anyone else had this problem and do you have zincs on both hubs? BTW my setup is with Yanmar saildrives. I'm wondering if it could be related to the water intake that was added stbd side fwd for the AC unit. I notice corrosion there and plan to replace with a Marelon seacock as well. Maybe there is something else going on electrically?
Bob Johnson
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SecondWind
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Re: electrolysis

Postby SecondWind » Wed Apr 30, 2008 9:30 am

Bob,

We had some electrolysis on our starboard drive and needed to replace that prop. We have a Dynaplate on that hull that is slowly disappearing. One of the things we have done is to quit leaving the boat plugged in to shore power. We change the zincs every year and we have all Marilon thru-hulls.
Terry Green
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Bob
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Re: electrolysis

Postby Bob » Wed Apr 30, 2008 3:46 pm

Interesting....the first sign of problem was the stbd prop. I also have a Dynaplate fwd on that hull as well and the added through hull opposite the dynaplate. Bonnie and Roger on Kokomo have their SSB hooked to the Dynaplate but I don't recall if they are a LRC or not. I was going to do the same but now I wonder if that might be a problem with electrolysis. Maybe they are monitoring the board periodically and would comment.
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SecondWind
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Re: electrolysis

Postby SecondWind » Wed Apr 30, 2008 4:04 pm

Roger & Bonnie do not have an LRC, but outboards. Roger has never mentioned electrolysis that I recall. It would be interesting to know how his Dynaplate is wearing.
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Bob
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Re: electrolysis

Postby Bob » Tue Dec 15, 2009 6:59 pm

Well I changed the one bronze through hull to a Marelon fitting this season. It was a good thing I did as it crumbled in my hands. I also hooked the counterpoise for the SSB to the Dynaplate. I have a capacitive bridge between the radio and the plate. I was astounded to see the zincs both on the individual props and on the drive itself worn by ~50% in a period of 4 1/2 months. We are on a mooring far from marinas but close, about 100yds, from the Dragon Cement barge loading facility and tugs. I'm wondering if there is a stray current issue being close to this facility as there is shore power both to the loading barge and the tugs when idle. Any additional thoughts?
Bob Johnson

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