Shaft anode small bubbling
- Thread starter Ken13559
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- bubble bubbling shaft anode
Your fresh surfaced Zinc and Shaft galvanic corrosions stabilizing. If you dive a few hours later and still bubbling, you most likely have a stray marina electrical current. How badly was your old Zinc gone?
Jim...
Master Degree in Chemical Engineering that takes two minors in chemistry, but as all advice from me, it is worth what you paid for it.
Galvanic corrosion is a battery "discharging". To come to "Steady state" galvanic potential from a fresh zinc and stainless shaft make take a few minutes for the new battery to arrive at steady current flow. Depends on surface area of zinc to shaft ratio, temperature and salinity of your water.
Thats why I said...
Jim...
OK, but what is off-gassing and why is the anode doing it?Master Degree in Chemical Engineering that takes two minors in chemistry, but as all advice from me, it is worth what you paid for it.
Galvanic corrosion is a battery "discharging". To come to "Steady state" galvanic potential from a fresh zinc and stainless shaft make take a few minutes for the new battery to arrive at steady current flow. Depends on surface area of zinc to shaft ratio, temperature and salinity of your water.
My guess is that in the store Zinc turns grey from Zinc Oxide. As the battery discharges to be Zinc again, Oxygen is the bubbles.
Jim...
After thought...
BTW fast and a lot of bubbles suggest more just galvanic corrosion is taking place. Plus @whatfiero could be right too or additive air as the zinc oxide react away.
Jim...
BTW fast and a lot of bubbles suggest more just galvanic corrosion is taking place. Plus @whatfiero could be right too or additive air as the zinc oxide react away.
Jim...
Dang it you got me thinking on a Sunday no less!
The OP is in Singapore on a 33' Hunter. I now suspect the Zinc manufacturer along with high water temperatures.
Using a good USA made zinc...
The speed to arrive at a steady galvanic current flow is based on the surface area of the Zinc and the surface area of all less Noble metals that are in electrical contact with that zinc.
So one other reason for it to have sustained bubbles could be his zinc is too small for his boat.
Tip: Weight of zinc gives you longevity or time between changes. Surface area is the key to protection of your underwater metals.
Jim...
The OP is in Singapore on a 33' Hunter. I now suspect the Zinc manufacturer along with high water temperatures.
Using a good USA made zinc...
The speed to arrive at a steady galvanic current flow is based on the surface area of the Zinc and the surface area of all less Noble metals that are in electrical contact with that zinc.
So one other reason for it to have sustained bubbles could be his zinc is too small for his boat.
Tip: Weight of zinc gives you longevity or time between changes. Surface area is the key to protection of your underwater metals.
Jim...
Ken
You need actual data.
Check the potential of the shaft. Zinc reference probe on a wire goes overboard, VOM set to volts, reference probe wire to VOM -, VOM + to the shaft. Give us the readings.
Absent actual data the ideas mentioned so far are not very useful whereas this simple test will clinch a diagnosis.
Charles
You need actual data.
Check the potential of the shaft. Zinc reference probe on a wire goes overboard, VOM set to volts, reference probe wire to VOM -, VOM + to the shaft. Give us the readings.
Absent actual data the ideas mentioned so far are not very useful whereas this simple test will clinch a diagnosis.
Charles
I've been fitting this good quality Anode (not the China made stuff) and this is the first time I'm seeing off-gassing on the Anodes. The old one has about 40% left and as I brush it, it crumbles so I removed it and polish up the shaft area cleanly with steel wool. Then fit a new Anode. No problem there. Instruction on label was to tap with hammer to sit it in better. After tapping, off-gassing starts. I suppose that's due to the "Copper ball" in center of Anode touching the shaft thus improving the connections?
Yes, but you indicated that Chinese-made anodes are inferior, not me.
That suggests to me, 100% gone, as a protective Zinc anode. Not in electrical contact with the other metals. If you dive your boat again, and it still bubbling, then we can talk about size of anode and what Charles suggested... a complete Galvanic survey of your boat.
Jim...