Corrosion!!!!

P

patonga

New Member
May 7, 2009
2
australia
Boat Info
bayliner!!
Engines
2x350 merc
I put new annodes on 6 weeks ago and looked yesterday. As I previously suspected, there must be a current leak somewhere because one annode on one leg is zapped to about 70% and one on the other leg is about 75%. The strange thing is all the other annodes on the legs and the big one on the hull are untouched!!! First question. Why only 2 out of 9 affected? 2nd question. Wher should I start looking for the stray current or is it a job for the pros?

Marina Disconected the batteries and still reckon they have a reading of point 6 of a volt. Where they read this from I don't know.
What I do next, I don't know. They seem to have given up and have directed me towards an electrical "expert". I'll let you know what happens.
Is it possible to still read .6 when the batteries are disconnected?

Pete
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I'll be interested to read the replys about stray current so I hope they are plentyful but before we even get there, you say 2 are affected the others are not. Did you purchase & put them on yourself? Any chance those two are the wrong type for your water conditions?
 
it would help if you listed your boat and power in your signature.
 
Pete, whats a "Leg" where is it on your boat?

Pictures and less boat slang would help a lot to get our focus on your problem.

If the battreris were disconected and your boat was still leaking current, it can be shore power and the obvious, you ARE a BATTERY and have gaslvanic corrosion at work that is kicking electrons loose.
 
The zinc annodes were installed by the marina on my bravo2 legs/drives connected to 5.7 mercruisers . Saltwater use. no shore power for 6 weeks. Whats gasvlanic corrosion? Sounds expensive!!! And more to the point......how do I stop it?
Hope this helps your advice.
Pete
 
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Current is flowing from your boat out through the zincs and to ground.

Check to see if your boat has a "galvanic isolator" installed as this protects you against stray current in the ac/ac ground circuit.

Make drop dead certain that every wire bonding connection ( the thick green wires running alone) in your boat is clean, has tightly installed lugs and is securely bolted to the circuit (leads to engine block and or hull zinc).

If you fix any obvious problems, and are still chewing up zincs then The Isolator issue maybe the problem OR a boat on your dock can be leaking current and you are loosing zinc.

Consider these alternate possibilities: new boats close to you, (100 feet), Any neighbors recently have electrical work done, Marina have work done on their dock electrical system?

You can have a marine electrical contractor come to the boat with special meters (maybe rented as well). They drop an wire in to the water and then check for continuity from everything thing on your boat. A good marine electrician will find your "issues".
 
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