electrolysis help wanted

[Bill1565]

Help! I am eating up a zinc a month. I have a galvanic isolator. I use a silver chloride half cell and 110 on 110 off I show 0.06 amps at 0.9 volts between the water and my negative shunt. Battery negatives connected or dis connected. I'm stumped, don't know where to look next.

 

[Sailm8]

Bill, do any of your neighbors have a lift near by. Stray current may be the problem. No expert here but Bob A's boat eats zinc while mine goes about 3 or 4 months without a change. The difference, he is surrounded by lifts.

 

[Don S/V ILLusion]

Are those reading with the boat disconnected from shore power?

Second q - are you SURE you have only one ground return?

 

[Stu Jackson]

Bill, do you have neighboring boats that are plugged in all the time? Are you in a marina or do you have your own dock? Have you considered unplugging your boat for awhile and seeing what happens? Do you have Calder's Boatowners Manual? He has a very good writeup of the options you can examine.

Good luck.

 

[Stu Jackson]

Bill, there's also this: http://www.westmarine.com/webapp/wc...catalogId=10001&page=Marine-Grounding-Systems

 

[Charles Erwin]

Bill

Probably the most easy to understand is anything by Rifkin. See "documents" at his site http://www.qualitymarineservices.net/.

As to your situation I do not see that you measured hull potential with the shorepower cord completely disconnected.

 

[Bill1565]

Bill, do you have neighboring boats that are plugged in all the time? Are you in a marina or do you have your own dock? Have you considered unplugging your boat for awhile and seeing what happens? Do you have Calder's Boatowners Manual? He has a very good writeup of the options you can examine.

Good luck.

Boat is in my back yard. I'm the only boat in my canal plugged in all the time. I have the only boat lift for 4 or 5 hundred feet, but there is an underwater light two houses down. Off in the daytime, but still in the water.

Have Calder's book, will re study, but when I disconnected the grounds on all seven batteries,with no change in voltage or ampearage, I was stumped.

Will again try turning off breakers in my house, disconnecting shore power,but last time i did all that, I still had volatge differential.

 

[Bill1565]

Second q - are you SURE you have only one ground return?

Only one power cord. When I disconnect the battery negatives at the terminal, only ground is starter negative

 

[Don S/V ILLusion]

Only one power cord. When I disconnect the battery negatives at the terminal, only ground is starter negative

what about the question - was the boat plugged into shore power when you observed those readings?

 

[Merlin Clark]

Bill,
I built a short retaining wall last December to ease the slope leading down to our canal and when digging in the pilings I found 2 things: 1st was a 1/2 PVC pipe that was probably used to supply water to the dock in the past and the other was the water table in the yard was higher than the canal level.
This leads me to wonder if there might be an old and still live buried electrical cable leading in your or a neighbors yard that might complete (circuit) when it gets wet from sprinkler water, rain or the canal water level rising?
One way to check for this would be hire a utility locator service or rent a Schoenstedt (or equivilent) locator at the local tool rental place. A treasure hunter type metal locator might work but I have no experience with that. If you decide to do this get in touch and I'll give you a description of how it goes.

 

[Bill1565]

Bill,his leads me to wonder if there might be an old and still live buried electrical cable leading in your or a neighbors yard that might complete (circuit) when it gets wet from sprinkler water, rain or the canal water level rising?

Good possibility there is a live wire or two out there. There were davit pads behind the seawall, no davits, when we bought the house in'98 but could have been there previously. Will look into it. Also gonna re wire lift per next post.

 

[Bill1565]

Help! I am eating up a zinc a month. I have a galvanic isolator. I use a silver chloride half cell and 110 on 110 off I show 0.06 amps at 0.9 volts between the water and my negative shunt. Battery negatives connected or dis connected. I'm stumped, don't know where to look next.

Thanks for all the help. Problem apparently is my power pedestal or boat lift. Pedestal was used when I got it in '98. boat lift is maybe 10 years old, survived a hurricane, but apparently something went south last summer.

Power pedestal breaker off , cord disconnected I get get 980 mv, 55 ma . Cord connected I get 583 mv, 33ma. Don't understand it. Thought galvanic isolator was to stop current in green wire.

 

[bobtigar]

Help! I am eating up a zinc a month. I have a galvanic isolator. I use a silver chloride half cell and 110 on 110 off I show 0.06 amps at 0.9 volts between the water and my negative shunt. Battery negatives connected or dis connected. I'm stumped, don't know where to look next.

1. disonnect your shore power when you dont need it.
2. Buy a fish zinc and attach it to your prop shaft or transmission or engine(as long as the coupler is solid and not the flexible type).
The fish zinc should last 2-3 years-even in the worst situations. Bob