How to prevent marine growth on the propeller?

If we did not treat the propeller it was pretty much standard to dive and scrape the propeller clean when the summer holidays started in July.  A bad year I had to dive a second time in September. Typical we put the boat in the water in March and haul it out in late October.

The first product we tried was Prop-shield.  To my surprise it did work quite well. When we took the boat out of the water, there was no barnacle on the blades. On the hub itself you could perhaps see 5-10 barnacles.

The application of the product was a little bit messy.

Next test was to do nothing but remove the zincs. The Flex-O-Fold propeller is made of a very high quality bronze and should really not need any zincs if everything ells is 100%. Whiteout zincs the copper in the bronze oxidises and protects the propeller from marine growth.

When came out of the water 2011 there was no barnacles. But there was some pitting corrosion on the blades.  As we have an isolation transformer this was a surprise. It might be that the metal construction under water in the marina created an aggressive environment.

This season we tried the Jotun Aqualine VK antifouling.  The VK product is really not intended for use on bronze. I contacted Jotun who said it would mot probably fall off.  As you can see from the picture it was just close to the edges of the blade were paint fell off.

It was easy to apply. First I sanded the propeller and sprayed 2 coats of Jotun Vinyl primer followed by two coats of Aqualine VK.

The test results after app. 150 engine hours are very encouraging. 95 % of the paint is still there and no barnacles. We will give it a try next year as well.

If anyone have experience of any other product please feel free to comment.



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