oxidation on keel hunter 306

[brinky]

i just hauled my hunter 306 (built 2005) and applied a new coat of bottom paint.

the connection between the hull and keel got a new fiberglass coat before applying seahawk antifouling paint. this was done due to the small cracks on the front and back of the keel connection to the hull.

one week after being back in the water the port side of the keel looked like a scaper went over it.

what can cause this to happen in such a short period of time? i checked for ground leaks and found that my battery charger was the cause of a .5 V leak. when removed there is no voltage at all? can such a small amount of voltage cause such oxidation?

 

[Crazy Dave Condon]

On the 306, the keel when married to the hull uses 5200 marine sealant. When you state a new fiberglass coat was applied, do you mean epoxy barrier coat. Obviously the hull for painting was not prepped correctly. Please explain what you meant and a photo or two would help those of us to be more correct on helping with responses.

 

[brinky]

 

[brinky]

The first two show the keel and hull after cleaning the last one shows fight after she was hauled and cleaned. The hull and keel were redone with 5200 by the previous owner.

 

[Crazy Dave Condon]

I am not clear when you say fight after cleaning. Do you mean to say the third picture is after the hull was painted, placed back into the water and then the third is after the boat was pulled out? If pulled out, how long was it in the water?

You also inquired about an electrical charge if not mistaken. Have you ever put a sacrificial zinc into the water at your slip for about a week to see what is going on?

dave

 

[brinky]

explain

Dave,

sorry fight was a typo it needed to be right, that's what you get when typing on a "smart phone"!

Third picture is when i hauled her out, first and second is after she was cleaned. the picture in the first posting was made under water two weeks after she was back in.

i placed a sacrificial in the water near the boat but nothing happened.

the keel got an extra layer of fiberglass from the hull to about a 2/3 rds of the keel. this is about where the issue is. however it is also under the layer of fiberglass.

the experts here claim that the keel was just not cleaned properly and that there is some kind of contaminant in it which starts to "sweat" when sealed with bottom paint.

 

[Crazy Dave Condon]

First, it would appear that the prep was not done correctly. Secondly, you have to put a metal undercoater on first before applying fiberglass. Then I would even question the purpose of applying fiberglass when all you would have needed to do was to apply two part of epoxy barrier coat and then anti fouling paint.

as for the sacrificial zinc, I was trying to rule out everything for example electrolysis.