corroded mast help

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corroded mast help

Postby desertfalcon » Sat Dec 05, 2009 1:01 am

The mast on my boat is foam filled and has several small holes through it as a result of corrosion. Pics to follow. Any opinions or ideas regarding both the integrity or lack there of, of the mast and also any thoughts on a repair technique suitable for this situation. Thanks in advance!

desertfalcon

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desertfalcon
 
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Re: corroded mast help

Postby DaveD » Sat Dec 05, 2009 3:32 pm

I'll post the suggestion I made. Maybe we can get some other inputs.

Step 1.
Wet/Dry 220 grit sandpaper dipped in Mineral Spirits, and rub out the corrosion and "white spots". Let dry, and wipe it down with a shop rag dipped in Mineral Spirits.

Step 2.
Use a Dremel too with a small metal bit to take those holes out a bit (NOT TO MUCH!), just enough to catch the corrosion. Make sure you grind it out with a "dove tail" type hole, you will see why in step 3. Follow it up by a wipe down with MS again, file down any rough edges.

Step 3.
Pick up some QuikAluminum Epoxy Putty Stick. Works like the plumbers epoxy, you take a slice, mix it in your fingers like silly putty until the 2 parts are mixed, then work it into those holes, trying to keep it smooth. When the epoxy cures, sand it off with the 220 grit paper till smooth.

Step 4.
Spray it with this to seal it:
http://rustoleum.com/CBGProduct.asp?pid=100

Rinse repeat, enjoy.
A bad day sailing is better than a good day at work...
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Re: corroded mast help

Postby joecomet » Thu Sep 29, 2011 10:00 am

Still in the 'overhaul' stage. While we are replacing the wood work and refinishing the deck and cuddy, I though i would try to take on refinish of the mast and boom. Am sanding, and plan to coat with 'Rust-O-Leum Cold Galvanizing Compund'. Nice flat gray color. I might just try a couple of coats and stop there, and then again may overcoat with top coat. Does anyone have experience with this material?
Joseph
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Re: corroded mast help

Postby DaveD » Sat Oct 01, 2011 9:18 pm

I would wonder if there would be some kind of reaction between the zinc in the paint (or compound as they are referring to it) and the aluminum of the mast. I believe that is made to paint onto bare sheets of steel to galvanize it.

Consider this bit of reading:
http://www.lytron.com/Tools-and-Technical-Reference/Application-Notes/Safeguarding-Aluminum-From-Water-Corrosion

A bit more scientific, but I'm a geek at heart.

I would think a thin lacquer or epoxy coat would do more to protect it then the stuff you suggested, since aluminum is pretty much corrosion resistant as it is.

If there are burrs sticking out and sail snags are a concern, they make an aluminum "water putty" that you can mold to fill in spots and sand if off.
A bad day sailing is better than a good day at work...
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Re: corroded mast help

Postby joecomet » Mon Oct 03, 2011 4:19 pm

David
Didn' get much from the site you sugjested.
But I think you are right about the product that I mentioned. I plan to return it.
Here is what Don Casey says in 'Sailboat Refinishing'. "The key to a long lasting finish is the prime coat. The specified undercoat for alluminum will probably be an acid-type primer that etches the metal to provide a better grip for the paint." "Forget about trying to protect your mast by spraying it with some kind of clear coat: by fall your deck will be aflutter with cellophane leaves." He reccomends polyurethane paint over the primer.
Will see what i can find for a better primer.
Joseph
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Re: corroded mast help

Postby DaveD » Mon Oct 03, 2011 4:26 pm

The site mentioned about aluminum's natural resistance to corrosion because it creates an oxidized layer that shields it from further corrosion.

I only suggested repairing the spots of bad corrosion and then spot sealing them with lacquer.

I guess I could have been more specific. ;)
A bad day sailing is better than a good day at work...
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