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  #11  
Old 06-09-2014
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Re: Why Are Aluminum Mast Painted?

To add weight aloft.

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Originally Posted by casey1999 View Post
Why are aluminum mast painted?

If you answer to protect from corrosion, then why is the inside of the mast not painted? The interior would get salt spray from all the holes in the mast and would not get the benefit of a rain shower or wash down. Now if the mast is anodized, I could see how that could provide good corrosion protection- and look good for a long time. Paint seems to be just a maintenance problem.

My mast is painted, and needs to be repainted. Should I just strip the paint and leave as bare aluminum?
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Old 06-09-2014
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Re: Why Are Aluminum Mast Painted?

I like the look of red hulls, not sure about red masts. Call me a traditionalist, but if it was me, and the stick was pulled for maintenance anyways, I’d be (light) sanding, priming and painting white. Not sure that I like big, open exposed slots on my spars. Have you considered putting in halyard exit plates to “fill – in” those open slots? Harking and others make these plates. Is the corrosion you see near screws or rivets? Without seeing your boat, I’d guess you have a little galvanic corrosion going on under the paint. I would clean up/sand. Then prime with aluminum primer and then paint the top coat. Tap and screw in “plugs” for your trysail hole pattern. You might want to drill a tiny weep hole at the base of your mast (rear side). My guess is you have accumulated a lot of water in it since the last time the stick was pulled.
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Old 06-09-2014
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Re: Why Are Aluminum Mast Painted?

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Originally Posted by GeorgeB View Post
I like the look of red hulls, not sure about red masts. Call me a traditionalist, but if it was me, and the stick was pulled for maintenance anyways, Iíd be (light) sanding, priming and painting white. Not sure that I like big, open exposed slots on my spars. Have you considered putting in halyard exit plates to ďfill Ė inĒ those open slots? Harking and others make these plates. Is the corrosion you see near screws or rivets? Without seeing your boat, Iíd guess you have a little galvanic corrosion going on under the paint. I would clean up/sand. Then prime with aluminum primer and then paint the top coat. Tap and screw in ďplugsĒ for your trysail hole pattern. You might want to drill a tiny weep hole at the base of your mast (rear side). My guess is you have accumulated a lot of water in it since the last time the stick was pulled.
Agree, If I paint, the mast will probably be white or maybe platnium. Some corrosion near rivets and some under the paint where the paint bond broke and water gets under the paint and cannot be washed away. As far as the base of the mast- there is actuall about a 2 inch by two inch hole in the base that allows water to drain out. During wash downs I actually shoot the water right into the mast (through the halyard exits) to rinse it out.
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Old 06-09-2014
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Re: Why Are Aluminum Mast Painted?

Maybe it's just me... but this painted mast and boom, just makes this boat "pop".
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Old 06-09-2014
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Re: Why Are Aluminum Mast Painted?

Most 'bare' aluminum masts are in fact clear anodized.. Aluminum will oxidize to a stable outer layer, but it's usually fairly rough/dusty when you rub or touch it. An example of that could be the rough, pimply surface on a below decks aluminum backing plate that didn't quite stay dry.
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Re: Why Are Aluminum Mast Painted?

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Originally Posted by Faster View Post
Most 'bare' aluminum masts are in fact clear anodized.. Aluminum will oxidize to a stable outer layer, but it's usually fairly rough/dusty when you rub or touch it. An example of that could be the rough, pimply surface on a below decks aluminum backing plate that didn't quite stay dry.
My mast base tabernacle is a fabricated from aluminum. Never was painted. Can be seen in the pic. It is like you say rough, but has developed a tough protective skin.
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Old 06-09-2014
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Re: Why Are Aluminum Mast Painted?

The corrosion resistance of aluminum varies tremendously, depending on the specific alloy. Think about a cheap generic bracket (Home Depot style) that develops the white pox in a few months, and compare that with the hull on an Ovni, which just forms a nice protective layer of dull gray oxidization. I donít know but I would bet that the extrusions that are used for most spars arenít anything special.

BTW, all that fancy colored anodizing, starts out as clear and then gets a dip in the dye tank. At least thatís what I was told by the company that used to do all our anodizing. Thatís why it fades, and red is the worst.
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Re: Why Are Aluminum Mast Painted?

Quote:
Originally Posted by Geoff54 View Post
The corrosion resistance of aluminum varies tremendously, depending on the specific alloy. Think about a cheap generic bracket (Home Depot style) that develops the white pox in a few months, and compare that with the hull on an Ovni, which just forms a nice protective layer of dull gray oxidization. I donít know but I would bet that the extrusions that are used for most spars arenít anything special.

BTW, all that fancy colored anodizing, starts out as clear and then gets a dip in the dye tank. At least thatís what I was told by the company that used to do all our anodizing. Thatís why it fades, and red is the worst.
Just did a quick search and found some interesting information:
Boatbuilding In Metal

Also, marine aluminum alloy would be 5000 or 6000:
Aluminum Alloys

I have check selden website and cannot find what aluminum alloy they use.
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Re: Why Are Aluminum Mast Painted?

I cannot really answer your question but I just repainted my 35 year old 50 ft mast this spring. Last year I was seeing a lot of corrosion and minor pitting around all the stainless steel screws and stainless hardware (e.g., around the winches, halyard plate covers, boom attachment, shroud attachments, etc.) so I labeled everything and removed all the hardware, which was no easy task. I used an impact driver, heat, penetrating oil and a lot of patience to get all the old frozen fastners off. I then sanded all the paint with a 50 grit sandpaper on a Festool Rotex RO 150 with vacuum, a wire wheel via a Makita electric drill in the recessed track and a dremel via wire wheel in the track too, and of course some hand sanding. Added three coats of Interlux gray barrier paint as the primer and three coats of White epifanes 2-part polyurethane via the roll and tip method. Came out okay looks even better from 30-feet Added many new fastners prepped with forespars lanocote, in fact with all the stainless steel I added a thin coat of the Lanocote. I painted the mast to help slow the corrosion process, it seemed like the thing to do, probably wasn't. Moreover my boat is in the same harbor as the Secretary of State's so I thought I'd spruce her up a bit giver her that Bristol look. My Catalina 22 and Oday javelin have anodized masts, never been painted and never will as long as I own them and both are probably 40 years old or more and look great.

Last edited by ambianceack; 06-09-2014 at 07:30 PM. Reason: forgot the colors
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Re: Why Are Aluminum Mast Painted?

Selden currently uses 6082 alloy. 6061 is the somewhat traditional alloy because it is a primary alloy in aircraft building but has 3-4 times the copper as 6082. The extra copper makes 6061 a lot more suseptable to corrosion.

A lot of class societies have disallowed 6061 because of the corrosion problem, but this is a relatively recent change (10 years or so). So what alloy any particular boat has is a bit of an open question.
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