How to Refinish Your Aluminum Propeller

Is the propeller on your outboard motor looking a bit worse for wear? Is the paint chipped and is corrosion setting in? It could be time to refinish it before it’s too far gone.

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The propeller on my 2004 Yamaha F8M outboard has over 10 years of use and it was showing. The paint was worn from the blade tips and lots of small chips were spreading like germs. While I had the motor off Summer Dance for the winter, I decided to refinish it before the 2016 sailing season.

DSCN3949
BEFORE – This propeller has seen some shallow water and needs refinished. Note the scrap of wood blocking the blade to take the spindle nut off.

At first thought, you might assume that painting a propeller is a simple job; just sand off the old paint and give it a coat of Krylon. But there’s more to it if you want to do it right and have the job last. The thing is, your propeller is very likely made of aluminum and most paints won’t stick to aluminum for very long.

Like any good paint job, the best results come from careful preparation. Before you paint it, you will need to sand your propeller thoroughly down to bare metal. Also smooth out any pitting from corrosion and other surface defects. A sandpaper disk attached to a rubber face plate in an electric drill works well on the propeller blades and some areas of the hub. But you’ll still need to do some hand sanding to get around the roots of the blades and in between the blades.

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Sanded and ready for paint

After you’re done sanding, wear rubber gloves and wipe the propeller down liberally with acetone to remove all sanding debris and skin oil that came from your hands. From then on, don’t touch the propeller with your bare hands, always wear clean gloves. The slightest bit of moisture or oil can cause pin holes in the finish that can allow water underneath and sabotage your work. A scrap of wood that fits through the spline coupler makes a simple handle.

Etch Where it Scratches

For paint to stick to aluminum, you need to use an etching primer—one that bonds chemically to the metal, not just mechanically. I applied three coats of Rust-Oleum Self Etching Primer. It contains zinc phosphate, which the marine and aviation industries have used for many years to protect aluminum.

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After application of self-etching primer

After the last coat of primer is dry to the touch, apply a good quality top coat. I chose four coats of Rust-Oleum Professional High Performance Enamel.

AFTER - smooth as a baby's behind
AFTER – smooth as a baby’s behind

There are expensive anti-fouling propeller paints on the market but consider that they’re designed for props that are always submerged, especially in salt water, not part-time like most sailboat outboards. Also consider whether it’s worth one-third of the price of a brand new propeller just for paint that you’ll have to apply over and over as it wears off.

By using high quality, general purpose paint, you can refinish your propeller for around $10 with plenty of paint left over for other projects.


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8 Comments Add yours

  1. Kent s Kokko says:

    I notice that you have a proper saildrive prop. A lot of stock props are not optimized for sailboats. I had an exchange with Nissan about this and they recommended a Micky Mouse ear prop like you have. Basically you want to maximize torque with your prop at the expense of speed

    1. That’s right, Kent, torque for docking maneuvers, overcoming tides and currents, and powering through rough water.

  2. m4n4ger says:

    Excellent practical article as always! As a Jaguar 22 owner in the UK I’ve recommended your site to the UK Jaguar Owners Club, many of whom sail J22s (=Cat 22) and are equally impressed with your articles – do keep it up please!

    1. Thanks for recommending this site to your Jaguar club! Everyone’s welcome to visit and comment. The company that I work for is headquartered near Amsterdam, so I get over there once or twice per year. I really hope to make a stop in the UK on one of these trips to visit and I’d love meeting some owners and learning how you do things over there.

  3. Webster, Louis says:

    Thanks for the new advice.

    Unrelated: Am I right that a 1973 Cat 22 must be out of the water to replace the keel lifting cable? Or is there some trick to do this in the water?

    1. That’s right unless you either have scuba equipment, can hold your breath a long time, or know somebody who does and owes you a favor.

      1. Kent s Kokko says:

        I don’t know if there is anything special about a ’73, but I was able to replace mine while it was on the trailer. With the tongue of the trailer all the way down, there was just enough clearance to reach the fork. Others drop the trailer tongue, put blocking under the transom and bring the tongue up,again

      2. Hi, Kent

        Did you mean to comment on replacing a keel winch cable on Five Swing Keel Maintenance Blunders and How to Prevent Them instead?

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