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.
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.
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.
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.
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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