Does the strut need a zinc

Frank Langer

1984 Ericson 30+, Nanaimo, BC
I am getting conflicting advice on adding a zinc to the strut. I have two zincs on the prop shaft but the rubber cutless bearing insulates the strut from the shaft. One mechanic says to add a zinc to the strut, another in the same boat yard says that drilling a hole in the strut to add the zinc will weaken the strut and is not necessary unless the strut is turning pink.
Any advice from the Ericson experts?


Member III
How does strut weakness compare with a drilled hole vs. a rotted strut? I have a small zinc on my strut, consider it an ounce of prevention.


Member III
I have had a zinc on my strut on my 87 E34 since I bought the boat in 2011 with no problem and no pink discoloration. The zinc was already there when I bought the boat so I do not know how long zincs have been used there.


Member III
Pink in bronze is caused by dezincification, a sacrificial zinc is intended to prevent galvanic deterioration.

Galvanic corrosion needs dissimilar metals, an electrolyte (salt water), and an electrical current (stray current from other boats for example). Sacraficial zincs, galvanic isolators, or isolations transformers interrupt this process.

Kenneth K

Contributing Partner
Blogs Author
Frank, I read concerns about weakening the strut too, but did it anyway. After drilling the first hole in the strut and discovering the bronze is thicker, harder, and more difficult to drill than I had imagined, I added another hole for a second zinc. I have no concern whatsoever that the holes weakened the strut.

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As to the conflicting comments from the boatyard--if it's okay to drill into a strut that is already pink and weakened by corrosion, it must, therefore, be okay to drill into a strut that is intact and solid. That second guy's comment makes no sense.

Also, I was advised to remove the bottom-paint from the strut because of the claim that the copper in the paint can accelerate galvanic corrosion of the strut.
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