Vent Fitting Corrosion

healerf18

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Vent Fitting.jpg

Hi Everyone,

I have a stainless steel (applied by the factory) vent fitting near the bow of my aluminum boat and it appears I'm getting some electrolysis corrosion. Any ideas how these fittings are removed (there is no access from inside) so that I can repair the corrosion? :hmmmm:

Thanks!
 

copperlake

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It's quite likely that that fitting is actually chrome plated bronze and it looks like you have a lot of festering under the paint, if I'm seeing the lay correctly. They make plastic ones, which I would replace yours with unless it's in danger of being struck. I've seen this before. It sounds like it has been installed before other welding was completed. These fittings can only be removed from the inside. Good luck, but you're probably in for some unexpected and problematic maintenance.
 

healerf18

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Thanks for the reply copperlake. That's helpful. I'll do some more research and see what I can come up with.
 

KenaiFly

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If that is one your Kingfisher I'd be talking with a dealer about warranty.

Dissimilar metals and lack of O2 under paint causing corrosion of aluminum as the oxygen is consumed. The aluminum-oxide protective layer is consumed and the paint bubbles up. Also known as crevice corrosion. The way to fix it is isolate the two metals from each other. Use a rubber gasket or similar. I see this on all sorts of boats with paint or decals over aluminum. If there are other metal thru hull fittings they will do the same thing over time. Even the stainless hardware holding fittings that touch the aluminum will cause this. Here is another common example...

20160922_105901.jpg
 

rpdeines

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That looks like the anchor rode/chain locker drain. I would have a welder install a small diameter aluminum pipe with a 90 bend on it. That's what I'm going to do on my kingfisher sometime latter this summer. Rob B has a new boat with this exact set up I mentioned above. What year is the boat? I don't think they warranty the paint, but it wouldn't hurt to ask.

I'm currently looking at stripping some of the paint and going the bare look but I may repaint some of areas that need minor touch up.
 

healerf18

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Great info KenaiFly. I've been doing some research and you have summarized it well. Thanks.
 

healerf18

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rpdeines, yep, it's the anchor rode locker drain. For better or worse, there is a false aluminum bottom in the anchor locker itself so there is no access to the backside of the fitting. Great idea on the aluminum fitting. I'll look into it. The boat is a 2013, and nope this isn't covered by warranty. I see, however, that they are fitting their new boats with plastic caps.

Yes, the paint is awful pretty, but this is a good example of why aluminum is best left without it.

Thanks for the comments!
 

MacGyver

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rpdeines, Yes, the paint is awful pretty, but this is a good example of why aluminum is best left without it.

Thanks for the comments!

Having the boat painted is not the cause of your corrosion problem. It was cause by the manufacture not installing a stainless steel vent fitting on a aluminum boat correctly.

It was mention to use a aluminum vent and the newer boats now use a plastic vent. They will also corrode if they are not install correctly. It will take longer and you may not see the effect of the corrosion until it to late. But it will happen corrosion has time on it side.
 

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