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Corrosion Protection for Bronze Strut

Kenneth K

1985 32-3, Puget Sound
Blogs Author
The PO kept my boat in fresh water for the last 20 years, so it had no zincs attached to the strut. I now keep it in the south Puget Sound.

At last haul out, the yard guy commented that I should at least, 1) not paint my strut with copper-based anti-fouling paint (as I had) because it can cause the bronze to be sacrificed vis-a-vis the copper, and/or, 2) scrape the coatings off the strut and attach a strut zinc.

Under the anti-fouling paint, the strut is covered with a thick (many times thicker than paint) whitish coating. Where still in place, the coating adheres very well and is hard to remove. The white coating has, however, chipped off on maybe 10-15% of the surface of the strut.

20160406_171855.jpg

As per the yard guy's recommendations, I'm planning on:

- Brushing the strut down to bare bronze (the bronze appears to be in good condition on the half I have completed)20170819_191810.jpg

- Attaching two small disc-zincs (one above the other) to the trailing edge of the strut (the trailing edge is flatter than the leading edge).
- Painting the strut (after the zincs are attached) with this stuff Pettit-1792.jpg (leaving the zincs unpainted)​

Is that a sound plan, or should I have sought input here BEFORE sanding down half of my strut?????
 
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tenders

Innocent Bystander
You can probably get away with a lot of shortcuts if the boat is still being kept in fresh water, but I'd still keep it fully galvanically protected, even if the protection doesn't need to be replaced very often as it does in salt water.

Sounds like somebody put barrier coat over the strut. I don't know if this is a good idea or a bad one.

The strut should have a hole drilled in it with a "button zinc" on either side that looks a bit like the top of a mushroom. The strut should be painted, except for where the button zincs contact it, unless you enjoy dragging the resulting growth along with you wherever you go. Many freshwater boats use magnesium components instead of zinc, but as far as I can tell this is a relatively recent phenomenon and may be a sinister plot on the part of magnesium companies to sell more of their products to unwary freshwater sailors.

I use the Rustoleum version of the zinc spraypaint you're referencing...on my propeller. (Home Depot, $7 a can.) Not sure if it really helps, but it doesn't hurt and doesn't erode off in a few hours of engine use like bottom paint does.
 
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