Anode Corrosion

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Mike Gibson

Mike Gibson

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Jun 4, 2004
19
Beneteau Oceanis 461 Raby Bay Queenland Australia
Hi out there in Beneteau land. Can anyone help me with a solution to why my anode at the rear of my prop dissappears so quickly. I put a new one on 3 months ago. This week I slipped my 461 for its anual maintenance and already it is half eroded. I moor in a marina and always attach my shore power. At a recent boat show I was told if you are the sacraficial anode in the marina you will loose you anode quickly. Does anone have a solution? Should I hang an additional anode over the side like some racing boats do. Is there anything I can do without adding more anodes on the hull? Thanks in anticipation to all who reply. Mike Gibson Brisbane Australia
 
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waldo24038

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Jun 4, 2004
5
Catalina 380 X-DREAM
STRAY CURRENT AT THE MARINA

sUGGEST U GET THE MARINA TO LOCATE SOURCE OF STRAY CURRENT IN THE WATER. CHECK TO SEE IF ANY ELECTRIC LINES ARE IN THE WATER AND CHECK WITH OTHER BOAT OWNERS ON THE GENERAL DOCK AREA.
 
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Pat McCartin

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Jun 3, 2004
347
Hunter 30_74-83 Lake Lanier, GA
Becareful

More sacrificial anodes are not always better. There is a critical ballance that when crossed your prop and shaft become the sacrificial anode not the zinc. First question...Are your anodes proper for salt water? There are two kinds, zinc and aluminum compoumds. I can't remember which is which. Second...Do you have a galvanic isolator on the boat? Third...Are there any steel hulled boats near you? I'd also sugest getting the marina to check the water for stray current Pat
 
Mike Gibson

Mike Gibson

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Jun 4, 2004
19
Beneteau Oceanis 461 Raby Bay Queenland Australia
Anode in Salt water

Thanks Pat for your reply, The anode is in salt water. There are no steel boats nearby. I don't think there is any stray current, but I will mention it. At the last boat show, there was a product that sat in the earth wire just after the boat inlet (240v shore power connection, boat side). The product was stated to reduce your earth leakage and protect your anod. do you know off this type of device?
 
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Pat McCartin

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Jun 3, 2004
347
Hunter 30_74-83 Lake Lanier, GA
I've heard of that.

What you describe sounds like a Galvanic isolator. Check out this link, http://www.marinco2.com/showProduct.asp?p=2450 This unit is instaled in the shore power wiring in the boat. It is instaled in the earth ground wire and ties in thru other terminals to the boat ground/engine. It's suposed to block stray DC voltage. I don't have one, but I've insaled a few. I have no before/after refrence. Pat
 
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MarkL15337

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Jun 18, 2004
1
Beneteau 361 Warwick, RI.
My Anode problem on 361

I had the same problem on my 2003, 361. After 2 months in the water on a mooring, away from other boats, the prop zinc was gone when I hauled out. I checked the whole electrical system out and found that I had approx. 2 volts on the pump side of the hot leg for the bilge pump float switch (after I pulled the fuse out). Impossible you say!? At that point I called Cape Yachts, my broker, and their electrician came right down to check it out. Well, it turns out that during construction the bilge pump fuse block had crack and was shorting across the metalized mylar sound insulation in the engine compartment. It took a couple of hours with a multimeter to find this one.
 
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Gary

Keep it simple--use a zinc "grouper"

Had the same problem on a 361 at a mooring in an area with no nearby marina. The simple solution is to hang a zinc "grouper" over the side. The zinc should hang below the keel and be attached electrically to the engine ground. You can do this with a wire form the engine ground to the stern rail, and clip the zinc to the stern rail. Simple, cheap and effective. By the way it seems that this problem is more common--but not unique-- on Beneteau'a. I'm not sure why, but the european style wiring is different from what I've seen on US designed boats. Also adding to the problem is the fact that the zincs on B's and other boats without exposed shafts is smaller. If you have an exposed shaft you have lots of room to affix a big zinc. But an enclosed shaft is better design. Compromises compromises!
 
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Nic16936

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Jun 9, 2004
1
Beneteau 390 Sydney
Earth leakage

Hi Mike, I recently purchased an Oceanis 390, and noticed during survey that the anode was almost gone, and there was a lot of tarnish on skin fittings. I got an expert to have alook and test the boat while in the water, he took readings from keel bolts, engine and shaft. He found that the keel was not effectively protected, and recommended a 6mm wire between engine mount and keel bolt. The surveyor was very helpful, his name is Phill Pilcher, phone (02) 9971 6995. It only cost me a couple of hundred bucks for the test and report, and i'm glad i got it for the peace of mind. He also supplies the electrolosis blockers mentioned in other replies. Cheers, Nic
 
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