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Old 08-12-2017, 10:00 AM   #121
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I keep reading how copper bottom paint is bad on props and draws the zinc out of them weakening them. I was having no luck with bottom paint anyway. Falmouth harbor is so closed and stagnant it makes for quick growth and huge barnacles. My previous boat I did the same: Pettit underwater zinc, epoxy bottom paint, sandblasting and copper plating, wax. Nothing worked.
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Old 08-12-2017, 04:35 PM   #122
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Yeah, everything in life is bad for you as many preach. Bottom paint alone did not work for me. Using the method I described worked and I continue to us it.

EDIT: If I remember after haul, I'll try to post pictures of what the metals look like....good or bad.
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Old 08-13-2017, 09:11 AM   #123
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Quote:
Originally Posted by cappy208 View Post
I keep reading how copper bottom paint is bad on props and draws the zinc out of them weakening them. I was having no luck with bottom paint anyway. Falmouth harbor is so closed and stagnant it makes for quick growth and huge barnacles. My previous boat I did the same: Pettit underwater zinc, epoxy bottom paint, sandblasting and copper plating, wax. Nothing worked.

Cappy--

I returned to your post to comment on bottom paint and props. I looked into the materials used in props such as manganese bronze and also NiBrAl or nibral props. What I noticed is that in both materials the amount of zinc is small. Also the relative volts of copper to manganese bronze measured with Calomel half cells are almost the same ranging from -2.5 to about -3.8 as best I could read the chart.

That is a very small difference and I am doubtful any zinc depletion can happen. Nibral has a larger voltage difference but has a pitifully small amount of zinc.

Others may comment although my opinion is copper paint shouldn't be a cause for zinc depletion in props.

Copper plating? Gees, I though I was the jerk to spend $100-200 getting my props plated. Heck, it was worth giving it a shot.
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